# Poor Running



## 69 237 (Feb 18, 2018)

Im trying to figure out whats going on with my 69 LeMans. I rebuilt the 350 motor and break in seemed to go ok. After break in I have been having problems getting it to idle and it does not want to accelerate. When I set the initial timing to 12deg it runs (~10"inHg in park), but seems like it wants to stall out. When I put it in gear it bogs down and stalls out. I noticed that when I pull the vacuum line off it doesn't change the idle at all. I can bump the timing up to 18degs and it runs better but still irregular. When I put my hand over the air horn it doesn't pick up speed.

When I advanced the timing to where I got it to run, I took it out for a spin and it has almost no power. I give it gas and it almost acts like its choking and wants to die. If I back out of the gas it will start to slowly accelerate and then it will pickup once its in second gear and ~2200 rpms or so.

Does anyone have any idea what could be going on?


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## PontiacJim (Dec 29, 2012)

10" of vacuum? Do you have a really big cam? Maybe too much for the engine and you have lost idle quality and bottom end power? If a big cam, did you make sure you had enough clearance between the top of the piston and valve at maximum lift so the valve is not kissing the piston?

Wrong intake? Single plane intake vesus a factory 180. You will lose bottom end with the single plane intake and it will begin to pick up at higher RPM's.

Timing chain/gears installed a tooth off. Did you use a degree wheel? Cam could be retarded which will hurt bottom end and pick it up at top end RPM's. 

Vacuum leak? New PCV valve & grommet?

I assume the carb (type?) is OK, ie new, rebuilt, and in good working order. No gas smell from flooding over? Too lean? Not too large or mechanical secondaries?

Valves adjusted too tight or incorrectly. Have you pulled the valve covers while the engine is running to make sure they are all operating and lifting the same height - ie worn down a lobe on the cam during break-in? 

If you milled the heads and did not check your valve geometry at the rocker arm/valve stem to make sure it is positioned correctly, you could have a valve or two being held slightly open. Had another member (or 2) that experienced poor engine performance due to this. Zero lashing the valves with the use of poly locks took care of the problem in one instance and the other found a poly lock too tight and had to re-adjust a valve to fix the problem.

Stock exhaust manifolds? The heat riser valve could be stuck shut if stock exhaust manifolds. Even exhaust flow coming out of both pipes?

Blown head gasket? Have you pulled the plugs after running to inspect for both rich/lean running or water?

A number of things to check.


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## 69 237 (Feb 18, 2018)

PontiacJim said:


> 10" of vacuum? Do you have a really big cam? Maybe too much for the engine and you have lost idle quality and bottom end power? If a big cam, did you make sure you had enough clearance between the top of the piston and valve at maximum lift so the valve is not kissing the piston?
> 
> Wrong intake? Single plane intake vesus a factory 180. You will lose bottom end with the single plane intake and it will begin to pick up at higher RPM's.
> 
> ...


1. It is a rather large cam. I didn't think it would be that bad, but it's a [email protected] 0.050 intake cam. I actually had the motor run really well with a larger cam, but that cam did fail. No interference. 


2. And 5. I am running a stock manifold and quadrajet that I rebuilt with guidance from cliff ruggles book. It doesn't seem to be flooding as I really think I could smell it. 

3. The cam was degreed and it lined up with the dots.

4. Pcv valve and grommet are new. 

6. This cam was checked after break in and the lobes are good. 

7. I did have the block decked 0.023 and used the same pushrods. Could that really be the issue? I am using stock length push rods and poly locks. I have set to zero lash then 3/4" of turn so it should be 0.037" preload. 

8. Stock manifold woth the rise stuck open. It is a single exhaust but a larger muffler. It was on it when I got the car amd I suppose it could be getting clogged up. The exhaust was fine before I parked it 2 years 

9. I don't think it has a blown head gasket, but that would be something to check. All the plugs have brown/Tan insulators with dry black soot on the nose. 

When I try to accelerate it seems so slow. It wants to go to 3000rpms creeping then shifts hard into 2nd and continues to be slow until I gain speed and then it gets better.


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## BearGFR (Aug 25, 2008)

Re-check your rocker adjustment to make sure they haven't changed. I had to re-read your post before I saw that you're running poly-locks - so that does make your valve train adjustable. The stock Pontiac system with bottleneck studs is non-adjustable and sometimes folks make that mistake. 212 @0.050 is not a "big" cam by any stretch of the imagination. It should be making a LOT more than 10" of vacuum at idle though, I'd expect at least 16" inches or more so start looking for vacuum leaks. Check all the hoses, power brake booster, intake manifold seal, etc. A quick way to check for intake leaks is to get a can of spray starting fluid. With it idling, carefully spray it at all the points where the intake meets the heads. Use one of those long tubes like comes with cans of WD40 to try to hit the underneath sides of the ports too. If doing that makes it speed up, you've got a leak at that point.

Bear


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## PontiacJim (Dec 29, 2012)

Agree with Bear - not too big a cam and you should have more than 10" of vacuum. Typically, I back the poly locks off until the you hear the clicking sound, then slowly tighten until it goes away. Wait a few seconds for the lifter to normalize and if no more clicking -good. If it begins to click again, then tighten just a little more until it stops. Once the rocker arm stops clicking, turn it 1/4 turn and lock it down. Personally I think 3/4 may be too much, but I also know each company has their own way of doing this, and 1/4 a turn has always worked for me.

I would try to figure out why you are only running 10" of vacuum. Look for the obvious and do the test as BearGFR pointed out. If you have power brakes, the grommet at the booster can dry and crack and the check valve that goes into the grommet can also go bad. I might simply plug the fitting on the carb and fire it up to see if there are any vacuum changes. You don't have to drive it, just check your vacuum reading with it capped off. Again, it may be too tight on the rocker arms so I would re-do these and see if the vacuum increases - watch your vacuum gauge as you adjust them. 

The black sooty end of the electrode could mean a little rich. New air cleaner element? I assume points? I like to keep the plug gap at .035" whether I use a hotter coil or electronic ignition. If you have points, have you checked the gap/dwell? If they have been sitting for a while, they may be in need of a light filing to clean them up and then re-gap and set the dwell.

Try one thing at a time and let us know on the progress, eventually it will get worked out. :thumbsup:


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## 69 237 (Feb 18, 2018)

Thank you both for your suggestions! 

I am glad to hear the cam isn't too big, I sure didn't think it would be. Running rich shouldn't cause it to run so terribly should it? 

I'll check for vacuum leaks. I plan to make a home made smoke tester soon. I'm hopeful that a vacuum leak is all that's wrong. 

I been lashing the valves cold. Should I run it for a few minutes to make sure the lifters are pumped up and firm? I also did 3/4 of a turn since crower specs out 0.025-0.050" preload (half to a full turn). Is adjusting with the motor running a superior method? 

I have also kept the plug gap at 0.035" with Delco rs45 plugs. Awhile back I tweaked the dwell by ear and that smoothed up the idle a little but that didn't cure the problem.

The air cleaner is a 2 year old open element, but no miles on it. Many times I've worked on it I leave it off anywaus just to work with the carb.


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## BearGFR (Aug 25, 2008)

My money is on a vacuum leak - a significant one, unless your valves are a lot farther out of adjustment than it seems like they might be. Hydraulics are self-adjusting to a degree, especially at idle - they just have to be "close". If they were off enough to look like a vacuum leak that significant I'd expect there to be other symptoms that would show up at idle, like a significant miss-fire. I assume you've checked all the other 'easy stuff', like making sure the distributor is indexed correctly, and assuming the timing chain is "right". I think the recommendation for setting the rockers "hot" with it running is a better process for getting things dialed in. What you're shooting for is getting them tight enough so that they're quiet, but not so tight that pump-up at RPM starts to throw things off - it's a better way to "fine tune" the settings. However I don't think the difference in procedure between that and how you did it is enough to cause what you're seeing.

Bear


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## Lemans guy (Oct 14, 2014)

Are your distributor weights advancing? They could be stuck and when you try to accelerate you give it fuel, but it also needs spark advance, from the weights and increasing rpm's.....if they are stuck, or on wrong or not there you will get little or no power. The car will still run.

Also your dist vac can,.....is it hooked to full or ported vacumn.....and how much timing is the can pulling? You have to get this right, lots of these cans pull in too much timing, and with your very low vac, I would bet you may be getting a little at idle and what little you gets drops off soon....

Check the weights and springs are moving freely and that vac can is pulling and how much...you need to assess you timing before carb issues, of course as the gang said could be many things valves, rockers etc. But get timing right first.


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## 69 237 (Feb 18, 2018)

I have verified that the weights move and I have messed with the weights and I know it made a difference, but it's been too long since I messed with it. Im fairly certain I switched to using the heavier weights to smooth out the idle park to drive transition (400 rpm drop). 

The vacuum advance is full manifold vacuum. Ive always had smoother idling motors with full vs ported. The crane adjustable vacuum can is set to pull 14degs. I had inital set to 16-18 to smooth it out. 12 was almost diesel like super rough and didn't respond to removing vacuum hoses. And yes I set initial timing without vacuum advance.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> I have verified that the weights move and I have messed with the weights and I know it made a difference, but it's been too long since I messed with it. Im fairly certain I switched to using the heavier weights to smooth out the idle park to drive transition (400 rpm drop).
> 
> The vacuum advance is full manifold vacuum. Ive always had smoother idling motors with full vs ported. The crane adjustable vacuum can is set to pull 14degs. I had inital set to 16-18 to smooth it out. 12 was almost diesel like super rough and didn't respond to removing vacuum hoses. And yes I set initial timing without vacuum advance.


OK, I am not sure I am getting this correctly, so bear with me. You have full manifold vacuum to the vacuum advance. Your vacuum advance is factored at 14 degrees. Your initial setting at the crank is 16-18 degrees. If you take away 14 degrees of vacuum advance because that is what you get with full manifold vacuum, then your initial timing at the crank with the vacuum line disconnected would be 2-4 degrees - way too low.

Now if you have your initial setting at the balancer at 16-18 without the vacuum line disconnected and then you hook it up to full manifold, you now have 30-32 initial - waaay too much. Add in your mechanical advance in the distributor and you have yourself a time bomb just waiting to detonate itself apart.

You should set your initial at the balancer between 10-12 degrees and then bring in your mechanical and add the vacuum to that IF you plan on running full vacuum to it. (Initial + Mechanical + Vacuum Advance on full engine vacuum = Total advance)

You also need to know when Total Advance is in. With the ethanol gas, it should be anywhere from 2800-3200. Some will go as high as 3500 RPM, but this is something you have to play with using the springs/weights of the mechanical advance. Lemans guy will be able to answer better on this one.

Keep in mind that if you have an original balancer with the bonded rubber that these can slip and the marks will be off and setting your timing to them will be off. And, you want to make sure the correct harmonic balancer is matched to the correct timing cover and scale. People swap things around and they won't match, again, throwing timing off at the balancer so you cannot use it. I assume all your parts are still original to the 350. Did you happen to degree the balancer along with the cam?

Just for fun, disconnect the vacuum advance & plug the line. Set your initial at the balancer to 10-12 degrees. Take if for a test drive.

Now if the engine sounds crappy, with vacuum line plugged and disconnected, loosen up the distributor hold down bolt/clamp just enough so you have to use a little effort to rotate the distributor. Rotate the distributor right (Counter Clockwise - CCW/retard) until it runs rough. Note the position. Rotate it back (advance) the other way until it runs rough. Note the position. Now move it again counter clockwise until it runs nice and smooth. If it sounds slightly rough because you went to far, simply move the distributor back until it smooths out again. Leave it there, and take it for a spin. The distributor won't move because it is fairly snug, but can still be moved by hand. If you hear *ANY* pinging under load, back off the gas as that is detonation and bad for the engine. Distributor is too far advanced and you can pull over and turn the distrib. by hand a small amount counter clockwise to retard ignition - test again. If it ran good on the first drive out, you can also pull over, advance the distributor (Clockwise) by hand a tiny amount, and try again. Again, _NO PINGING_ should be heard under load. If at a point you hear any pinging, you want to retard the distributor by turning it a small amount by hand and try again. Repeat until it goes away under load. Timing is now set regardless of your timing marks which you can check afterwards.

This is timing the distributor/engine by ear and how many do it and is how I do it to fine tune the timing once I get the initial set-up at the balancer. Just have to make sure you listen for the engine pinging and back out of the gas immediately and adjust the distributor - retarding it slightly counter clockwise.

Now if you want, hook up the vacuum advance to a *ported* source on the carb. It is my understanding that the Crane vacuum advance is not adjustable with regards to vacuum, but rather, to how quickly the 14 degrees comes in, so keep that in mind - you will always have 14 degrees total and that cannot be changed, only the speed at which the 14 degrees kicks in.

:thumbsup:


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## Sixty7GTO (May 4, 2017)

I think there is a sever timing issue. Cam timing, distributor a tooth off, mechanical and vacuum timing locked.
I'd go with Pontiac Jim recommendations in his last post


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## 69 237 (Feb 18, 2018)

It has a brand new power bond street balancer. When I set the initial it was without vacuum adavance. I also have the limiter plate which allows you to change how much advance the can will give. 

I'm still thinking it's a massive vacuum leak or failing ignotion components. I've adjusted valves twice with little to no change and have messed with vacuum advance a lot. I used every combinatorial of dist springs but saw minor improvements and I believe I've tried initial timing of 12-18 degrees. I replaced the coil 2 years ago and it seems to spec out ok on resistance. I've also replaced points and set dwell. The only thing that could need replacing is plugs, cap, and rotor. 

I did notice there is a little blue corrosion on the cap inner brass terminals. Could that be enough to cause this big of a problem?

Can a distributor really be a tooth off? I thought that was a myth since it all boils down to Cap and rotor position and the amount you can move the vacuum advance can.


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## BearGFR (Aug 25, 2008)

It's possible to be off - but even though that suggestion always surfaces (and I've offered it myself) with something off that much I'd expect it to make a BIG difference in how the car runs, if it runs at all. Eliminate the easier stuff first.

Sherlock Holmes said, "When you've eliminated the impossible, that which remains - however unlikely - must be the truth."

So that's what you do now. Put on your thinking cap and start explicitly testing for possible causes in ways that will either confirm them or eliminate them. Have you done that starting fluid test yet?

Bear


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## Lemans guy (Oct 14, 2014)

POntiac Jim and Bear are spot on. As far as dist a tooth off this sets timing off 13 degrees. Also the corrosion on brass tips can cause lots of rough running. You have the stop limiter at 14 on the vac can, and at full manifold, but if it pulls it in early and you have 18 base, like PJ said way too much....

32 coming off idle, should be rough unless you have a real radical cam some can take more timing their. I know that you probably double checked that your dist is not set at TDC on exhaust stroke, ez to make that mistake so make sure. Of course you verified firing order, counterclockwise, again e to check it clockwise and think you verified it.


so you know you have 14 on the Vac can, but at what vac is it all in?....by the way 10 is what you want on vac on today's gas.

The weights can stick, the gear must be fully seated, and the dist should turn smooth in your hand when out of the car. Also I have had a bad condenser, they happen from cheap import knockoffs, you could try another one, they are not expensive and make sure your connections to points and condenser are good and not corroded. A rebuilt Pontiac Distributor is about $55 come with new points and condenser, weights springs. Add a cap and rotor and recheck, or borrow one from a friend and recheck.

Let us know what happens, could be carb as well, but usually ignition issues.


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## Lemans guy (Oct 14, 2014)

Ps best way to check for vac leak is with a smoke machine, all repair shops have them, they can hook it up in a couple minutes and smoke it while you watch......saves lots of time....


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## 69 237 (Feb 18, 2018)

I dont have the car on site yet so im limited to weekend work. I have made a smoke tester that I plan to use first thing. 

I really thought only the rotor and cap position in the distributor was the big thing. The vacuum advance can is closer to the firewall than stock so perhaps it is a tooth off? It's odd that the distributor sits flush with the block if it is a tooth off.


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## Lemans guy (Oct 14, 2014)

Yes rotor and cap is the key. And if it hits right it will be right. But the distributor is positioned by the factory so the vac can has room to turn and not hit the intake. How they ensure that is to put a small dimple on the side of the dist gear, which must be located on the same side as the rotor tip.

The gear is held on with the roll pin, if it is not put back with the correct orientation, it will be a gear off on positioning and the can may hit the intake. if you mark the distributor base to the block, but get the dimple wrong it can mess up the position. So you may want to check as it may give you more clearance.

Make sure you have a good coil to cap wire and it is properly seated in the cap and coil, they can pull up and give you trouble. The rotor button must make strong contact as well under the cap.


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## Lemans guy (Oct 14, 2014)

And a tooth off will not change flush with the block,...it is a tooth off in the circumference.


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## 69 237 (Feb 18, 2018)

I got it running a lot better today. I used my smoke machine, but there were no leaks. So I went ahead and replaced points, plugs, rotor, cap, and plug wires. I ended up fighting with the points as the were garbage out of the box. I set the timing to 14degs base and I'm currently running 16 degrees of vacuum advance. I know 30degrees at idle is a ton, but that is where it runs the best. 

It now runs 14in hg at idle in park (800rpms) and smooth 550 in drive. It responds to the idle mixture screws which are 2.5 turns out. 

I now need to take care of the stumble on take off and what I think is the th400 vacuum modulator. It shifts late and firm which I think is due to the lower vacuum amd stock modulator.


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## Sixty7GTO (May 4, 2017)

While you're at it, check that vacuum line going down to the tranny. Then put a vacuum pump on that modulator and see if it holds vacuum.


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## 69 237 (Feb 18, 2018)

I will check the modulator the next time I get a chance. I want to say the cam timing is only advanced 2 degrees instead of 4. It was degreed at 110 and speced at 108icl. Would 2 degrees make that big of a difference? 

I also think bumping up my idle should help too, right?


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## BearGFR (Aug 25, 2008)

69 237 said:


> I got it running a lot better today. I used my smoke machine, but there were no leaks. So I went ahead and replaced points, plugs, rotor, cap, and plug wires. I ended up fighting with the points as the were garbage out of the box. I set the timing to 14degs base and I'm currently running 16 degrees of vacuum advance. I know 30degrees at idle is a ton, but that is where it runs the best.


Is that 30 at idle with the vacuum can on the distributor connected or disconnected? If that's with it connected... what is it with it disconnected and the vacuum line plugged so that it doesn't create a leak? My 461 is quite happy with 15 initial (no vacuum) and 20 in the distributor mechanical advance for a total of 35 "all in" at WOT. I've never checked what the vacuum canister adds, because it doesn't really matter.



> I now need to take care of the stumble on take off and what I think is the th400 vacuum modulator. It shifts late and firm which I think is due to the lower vacuum amd stock modulator.


Firm is ok, and actually easier on the transmission. Late can indeed be caused by a bad modulator.

Bear


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## 69 237 (Feb 18, 2018)

Yes, the 30 degrees is with vac advance connected. It's at 14degrees without vacuum advance. Any higher and it runs rough. It smooths out exactly where I've got it. When it's hot it starts right up so I know that's what it wants. I believe it's all in around 34-36 so it should be fine on timing. I could add lighter springs to see if it wants the mechanical in sooner. 

I have a feeling the late shifts would make it sluggish. The motor wouldn't get a decent load with the higher rpms. 

Thanks for all the help. I plan to get a vacuum tester and check the modulator out next time I can. 

I think my hesitation is due to the primaries being too far into the transition slots at idle. The accel pump is wet up top, but it has a very healthy squirt on both sides.


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## PontiacJim (Dec 29, 2012)

*69 237*: "I think my hesitation is due to the primaries being too far into the transition slots at idle. The accel pump is wet up top, but it has a very healthy squirt on both sides."

*PJ*: Just a thought. Its possible that your float level is set too high, and under hard acceleration, gas can slosh out the secondary metering rods where they go down into the carb if the problem is when you nail the gas. You will see that these holes are a little oblong. BearGFR has pointed this out and I have done this myself, you can put a piece of cellophane tape on top of the carb gasket to cover these holes on the gasket, then install the carb top and close it up, and then when you install the secondary rods/hanger, punch a hole through the tape with the rod making sure it slides up and down easy enough, and then install the rods on the hanger and install.

This of course can only be done with the carb top removed or when your rebuild the carb. But, I would first make sure my float level was correct and that I had a new float. The cellophane tape is just an extra precaution and will create a smaller hole that the rods go through versus the larger oblong hole and can stop gas from sloshing out and into the secondaries on hard acceleration - just something to consider as you keep checking for a solution.

And just for fun, if the hesitation/stumble is an off-idle problem I would bump the idle up to 650 in Drive so see if it gets better as sometimes when you go with a bigger/different cam than stock, you may need a higher RPM in Drive so you don't get a stumble. One of the reasons a higher stall converter is recommended with a larger cam. :thumbsup:


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## 69 237 (Feb 18, 2018)

I changed to lighter dist springs and that helped, but it was still off. I bumped up idle speed to around 750 rpm and that really helped. The primary throttle is into the horizontal transition slot and well into the vertical slots too. The reassuring thing is that I can kill the car by turning in the idle screws. 

Tuning the carb by highest vacuum gives me 11inhg in drive and 2 5 turns out. It ran a lot better with 3.5turns out though and it doesn't appear to bog down the idle if I keep turning the screws out. It seems like it wants more gas going down the road, but the plugs are creamy tan and it doesn't pick up with a vacuum leak or a hand over the carb. 

Im currently concerned with two things. The park idle is 1250rpm to keep it at 750 rpm in drive... I'm afraid that will do harm. The idle vacuum also rapidly and constantly fluctuates between 10.5-11inhg. I adjusted the valves hot to a half turn after zero lash. If any seemed more loose than others, I made it 5/8. It still fluctuated.


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## PontiacJim (Dec 29, 2012)

My thoughts. Your valve adjustment is too tight. Have had 2 members find that their adjustment was too tight which affected engine vacuum - it was low. If the valves are held open just a sliver or even bouncing because the adjustment is too tight, your vacuum will be low.

Adjust the valves with engine warm and running - have your rags ready and a fire extinguisher just in case 'cause it can get messy. I would also try to get that idle down first if possible at this point. You can even keep your vacuum gauge on the engine to watch if you see any changes in its reading - which would confirm a valve adjustment problem. Adjust back the valve off 'til it clicks, then tighten until it stops. Give it a few seconds for the lifter to pump down and "normalize." If it begins to click again, tighten just enough to get it to stop again. Once it no longer click, then tighten your poly lock 1/4 turn and that should do it. Unless you know what brand of lifters and exactly what the manufacturer states as the amount to adjust the lifter, stick with 1/4 turn.

If your heads have been milled any appreciable amount, this will change rocker arm geometry and your pushrods may no longer be the correct length. You can check this by putting some kind of marker/paint on the top of the valve stem. Rotate the engine over by hand a couple times and look at the wear pattern, it should be even in the middle - not worn more on one end or the other of the rocker arm travel. Ultimately, your rocker arm should be dead nuts in the middle of the top of the valve stem when the rocker is at half lift.

I don't like that you said "if some were more loose than others" because there should not be "more loose than others" and you might have a major issue beyond a valve adjustment.

Seeing you did have it running better and your vacuum was higher - my guess would be the valve adjustment at this point - and hopefully not worn cam lobes.

1250RPM in Park/Neutral is too high unless you have a REAL radical cam which would also explain the low vacuum, but you had it running well, so I don't think it is the cam.

Also assume you have high compression and run racing gas with timing set at 34-36 degrees all in? Aluminum heads?

I am not an expert on the Q-jet like a carb shop, but know enough to be dangerous and make them work well. We had another member who was having big time problems with idle on his 3 x 2 set-up. Ran great, but could not get it to idle down. I think I recall he played with the idle mixture screws as well and it didn't solve the issue. Problem turned out to be the idle tubes were too small and he had to enlarge them using a series of small drill bits used for such purpose. One step at a time and he finally got it right and the high engine idle problem was solved. 

Cliff Ruggles book shows photos and recommendations for the idle tube sizes. He points out that many Q-jet problems are related to the idle tubes being plugged or not the right size. Not sure what your carb is, I suspect this probably applies to most carb brands.

So I would begin with the valve adjustment, hooking up your vacuum gauge, and see if that improves things. Then go from there - you cannot keep making a number of changes, just one thing at a time. If an adjustment does not improve anything, then put it right back to where it was and move on to the next adjustment. :thumbsup:


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## 69 237 (Feb 18, 2018)

I'll take another look at the valve adjustment. I have crower lifters and the spec out around 0.025 to 0.050" preload. That should be half to one full turn after zero lash. 

The rockers weren't super loose and the lock nuts aren't crazy different heights indicating significant wear. The valves that were loose had some play, you could push down the pushrod just a touch by pressing in the rocker. So maybe lifters are leaking down a bit. That's not a conern is it? 

Compression is 9:1 with cast heads. The block was decked 0.020", but the heads have not been milled. 

I can get it idle lower. I have full control if my quadrajet idle circuit and I rebuilt it using Cliff book. It just has to idle at 1250 in park in order to idle at 750 rpm in drive given the rpm drop in gear. Maybe I need more idle bypass air?

I greatly appreciate all the help!


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## PontiacJim (Dec 29, 2012)

OK on the Crower lifters. Looking at their Pdf, they say .020" to .050" and they do not provide a manner in which to adjust the lifters with engine running. They do show the diagram for correct rocker arm/valve stem contact and mention those things which can affect pushrod length. 1/4 turn has always worked for me, but on the internet you will find 1/4 to 1 turn. You may want to email Crower and ask them the recommended turn of the poly lock with engine running/warm after you have established the zero lash setting.

The other method is spinning the pushrod with your fingers and tightening down until you can fee resistance, then tighten the extra 1/4, 1/2, 3/4, or full turn of the poly lock. I just feel that this is not the most accurate because resistance to you may be different for me. So I just prefer adjusting with the engine running.

Here is a bit of a guide in setting lifter preload. Maybe try their method of scribing a line on the pushrod and measure? Getting To The Bottom of Hydraulic Lifter Preload - Engine Builder Magazine

Personal thoughts: with 9:1 compression/iron heads, I would think 34-36 degrees total advance is too much with iron heads. In reading about many of the engines that had higher compression, ie 10.50 and more, might go that high. Your initial seems fine if it runs smooth and starts easy. My concern would be detonation that you may not even hear. I think I would rather see about 32 total rather than 34-36. With the lower compression, you should be able to run 89-91 octane? Going higher may not improve anything as the 9:1 would not really put out more power like it would if it were 10.5/10.75 compression and higher octane gas. You may need to fashion up a stop so the mechanical does not go past 32 and yet still keep your initial a 14. Just my thoughts on that one, but you know best so take my suggestion with a grain of salt. Some things simply have to be observed and tested by the owner - you. :thumbsup:

Your block being milled .020" could have an impact on pushrod length. Most machine shops will make a cut to the surface of the head just to clean-up and make sure it is not warped at any point on its surface, so this could add a tad bit more, but if you know the heads have not been touched than you can rule that out as adding to the .020" off the block. If it were me, I would have measured pushrod length just for peace of mind. Again, simple test would be as described earlier to see what kind of pattern on the valve stem tip the rocker arm is making.

I still think 1250 RPM is high even to get 750 in Drive. Seems the engine would over power the breaks a little, ie have to keep a good foot on the brake pedal to keep the car from taking off - unless you have a higher stall aftermarket converter? My '68 manual was no help on idle speed out of gear, just in Drive which is 650 for the TH-40o/400CI. But, if 750 works best, then I guess that is where I would set it.

On the Q-jet, since you rebuilt it you would know it better as well as its adjustments. Typically, I turn the idle mixture screws out 2 turns and go from there. It would seem you have yours set right for your engine using the vacuum method. But, 11" of vacuum is low and representative of a healthy street/strip cam with plenty of overlap.

Just keep tuning and keep posting your findings. The key in my book is to get the engine running its best and make sure there is no detonation going on. :thumbsup:


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## 69 237 (Feb 18, 2018)

So I checked valve timing today and it doesn't make sense. Number1 intake valve is opening at 46 before TDC at 0.050" lift. The cam is speced to open at -3 degrees ATDC at 0.050". I verified tdc too with a stop. 

How could it be that far off? How can piston to valve clearances work with it being that far off? Should I be concerned with piston to valve clearance when the cam gets advanced 43deg? 

I checked with the dial indicator on the end of the pushrod and it squared up. The hydraulic lifter was firm and not squishy... 

I'm going to take the timing cover off and advance the cam tomorrow..


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## PontiacJim (Dec 29, 2012)

69 237 said:


> So I checked valve timing today and it doesn't make sense. Number1 intake valve is opening at 46 before TDC at 0.050" lift. The cam is speced to open at -3 degrees ATDC at 0.050". I verified tdc too with a stop.
> 
> How could it be that far off? How can piston to valve clearances work with it being that far off? Should I be concerned with piston to valve clearance when the cam gets advanced 43deg?
> 
> ...



Where are you measuring the 46 degrees - off the balancer? If so, your balancer outer ring may have slipped if it is the original, not uncommon as they age and the rubber bond breaks down. Your engine would not run with 43 degrees BTDC.

The only way to accurately degree the cam is with a degree wheel. Once spec'd to the cam manufacturer's cam card, slip on the timing cover with a bolt or 2 and then slide the balancer on and see where you timing marks line up.


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## 69 237 (Feb 18, 2018)

I took the cover off and sure enough the cam gear was 4 teeth advanced. I lined the dots up on the gears and tested it with my exact same method (using a degree wheel) and it showed 0.050" lift at 5deg ATDC. I used my 4 degree advance keyway and it dailed it back to 3 deg BTDC to match the cam card perfectly. 

I dont know how it ran at all but it did. Must be a combination of my larger quench, huge stock valve reliefs and low lift cam.


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## 69 237 (Feb 18, 2018)

Night and day difference. It has 15inHg vacuum in drive at 700rpm. The drop from park to drive is only 200 rpm or so. It pulls good, but I need to tune in the ignition. It seemed to have a little rattle or something at 3600rpm, but was really going.

Any advice on choosing the right ignition timing? Use the inital that makes it run the highest idle and then the limit the max?


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## Dave Ray (May 18, 2018)

10 in/hg of IDLE vacuum is low for a cam with that .050 number. I suggest you recheck the valve settings. Pontiac's had a set distance valve setting, varying the push rod lengths to set the valve pre-load correctly. If the valves were ground and not "tipped" (stem height set correctly), and/or the block/heads were surfaced, the push rods could be literally too long. In all my engines, I run Smith Brothers (Bend, Oregon) adjustable push rods, makes valve setting on set distance valve trains a lot easier. 

"The vacuum advance is full manifold vacuum. Ive always had smoother idling motors with full vs ported. The crane adjustable vacuum can is set to pull 14degs. I had inital set to 16-18 to smooth it out. 12 was almost diesel like super rough and didn't respond to removing vacuum hoses. And yes I set initial timing without vacuum advance."

What all engines like is IDLE timing to be between 18 and 24 degrees of timing. Most engines won't start easily with that much timing in them, so, we have to get creative with the vacuum advance. To make the engine IDLE timing work, we need a reasonable INITIAL, you said you ran 12 deg/BTDC, good, but, not close to the 20 to 22 that engine likes. So, how to fix it? 

A vacuum advance set up correctly, run on full manifold vacuum, IS the correct answer. We have the INITIAL< plus the VACUUM degrees, on an advance restricted on degrees, to make the IDLE work. 

So, we need a vacuum advance that has an adjuster for the crankshaft degrees of timing needed to get us the IDLE level, without over advancing the IDLE timing. There are a couple of ways. 

On a stock vacuum advance, the factory added a simple section of rubber hose to the pin that pulls the point plate/magnetic pickup, to shorten the pin pull to the correct degrees. Most of the stock bushings are long rotted away, and replacement cans don't come with them. Easy to add a section of rubber vacuum hose to the pin, but, then, how many degrees are you restricting down to? 

On ALL GM vacuum advances, and aftermarket ones as well, degrees are related to the pin travel INTO the canister from an at rest position. With the rubber bushing in place, we have these numbers:

8 crankshaft degrees: .086 inch pin travel
10 crankshaft degrees" .110/.112 inch pin travel
12 crankshaft degrees: .130 inch pin travel

Stock vacuum advances come in a few different specifications, if a correct vacuum level is found, the degrees will probably be way off. Answer, look below, add a positive stop to the pull pin.

Now, for the Crane stop and vacuum advance. ALL Crane adjustable vacuum advances have an adjustment screw inside the diaphragm, adjusted by removing the vacuum hose and add ing an Allen key into the hose fitting until it indexes into the adjustment screw inside the unit. All the way right (clockwise as you look at the unit) is LOWERING the vacuum level it needs to work, and will bottom oout at about 4 in/hg vacuum. Conversely, rotating the screw left (counter clock-wise), will INCREASE the vacuum level the unit will work at. 

Then, there is the degrees stop plate. IT SHOULD NEVER BE MOUNTED TO THE END SCREW. The way the Crane instructions outline, increases THE SPRING RATE, and eventually defeats the vacuum level adjustment screw. 

The next question is, where to mount the stop plate? simple answer, on the other side of the pull pin, with an 8/32 screw and flat washer, so the plate stops the pin in its travel, NOT pre-loads the diaphragm spring.

The Crane plate works in this, on either a point, or HEI distributor, only takes a stop plate, and screw/flat washer, NOT expensive.

The benefits of full manifold sourced vacuum advance arfe better IDLE quality, better acceleration, less engine heat, not over heating, better cruise performance on no to light load engine operation, and better fuel economy. 

Now, this IS NOT AN AD, but, a complete set of instructions on just how to correctly mount the Crane stop plate, or, make a home-made stop plate, or, add the rubber stop, are available absolutely and totally free, no ads, no strings, just how to do it right, with pictures.

Ask for them at: [email protected] 

BTW, IF the engine likes ported vacuum for the vacuum advance, FIX THE MECHANICAL CURVE. Ported vacuum advance is ONLY for emissions engines with a functioning EGR valve.

Example: I know, its a Chevy, bear with it, we are speaking of an engine. ZZ4 crate engines come with 11 degrees of INITIAL timing, 22 degrees of mechanical curve, starting at 1,300 rpms, limiting well past 5,000 rpms. And,. GMPP INSISTS on ported vacuum for their vacuum advance. With those parameters, the engines are sluggish, run too hot, don't perform well, and usually ping. Bhe basics are there, just not applied correctly. The fix involves a vacuum advance pull pin stop to allow the pin to travel 8 degrees, .086 travel, and connect it to the full manifold vacuum source, same 11 degrees INITIAL, for 19 degrees of IDLE timing. The mechanical degrees stay at 22, but, change ONE spring to one that gives a start point of 850 rpms, limits at 3,100 rpm's. Engine is completely different, comes alive, doesn't run hot, drives like a real engine, gets better mileage, just plain nicer all around. NOTE: When some owners first got their engines, they tried to connect the vacuum advance to full manifold vacuum without restricting the degrees, and got an IDLE timing of well above 30 degrees. That didn't work well. So, I devised the stop procedures I outline in the instructions. Ask for the instructions, they are free, only your reading time is invested.

Another thing, as the instructions outline, never use a dial back feature on an analog ignition system with mechanical, and/or vacuum advance, those systems do not meed to "compute" timing, they need straight park readings. Mark the balancer for degrees, easily done, and leave the dial back OFF on the timing light.


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## 69 237 (Feb 18, 2018)

Thanks for all the detailed information!

I found the dizzy is giving 2 degrees mechanical. I set the initial at 8, with 10 degree of manifold vacuum advance (comes in at 7inhg) for a total of 18 at idle and 34 total at WOT. I always have ran manifold as that has given me the best results.

Vacuum is 13.5-14in hg I'm gear at 700rpm and 17inhg at 850-900park. 

Is this initial too low? How do you tell if initial is too low? I've also noticed that when I shut it off it will climb to 230F. No issues when running as it stays between 180-195 (this was all on a 88F day).


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## BearGFR (Aug 25, 2008)

The total for WOT operation does not include any vacuum --- think about it --- at WOT under load, the engine is not making enough vacuum to activate it so the vacuum diaphragm is out of the picture and not part of the equation. This is why you always disconnect the canister (and plug the line so you don't created a lean condition) when setting timing at idle. For optimizing total ignition advance on an engine for performance purposes, you're always working with no vacuum. Depending on which heads you have, and other things that affect combustion efficiency, flame propagation, etc. - Pontiacs tend to 'like' somewhere in the neighborhood of 34 degrees total for performance, but that can vary quite a bit with different heads, etc. "Total" in this case meaning the amount of initial plus whatever the centrifugal advance mechanism inside the distributor adds whenever it's maxed out. Vacuum only comes into play at part throttle, light load operation and it's purpose is to aid both fuel economy and engine cooling - again it's not part of the equation for power. What really matters for power is the total and how "quickly" it comes in.

If you want to find the absolute best power setting on your engine, it's time consuming and requires a day at the drag strip (or access to similarly accurate timing mechanisms), or a day making dyno pulls. You also need a way to set total advance, which means setting the timing with the engine running just above whatever rpm is needed to get "all" the centrifugal advance there is in the distributor (vacuum canister, if equipped, disconnected and the line plugged). Start with a conservative setting, say 31 or 32 degrees, and make a few passes (or a few pulls) to get an average. Make sure all the conditions as much as possible are the same on each test: beginning engine coolant temp, outside air temp, starting line technique, shift points, etc. Bump the timing up a degree and make some more tests to get another average. Keep doing this until you find the setting that produces the best power/lowest e.t. --- that's your setting. NOW grab your light and check what initial timing setting that is. You're not going to change it - just just seeing where it is so that the next time you need to adjust timing, you know where to set it at idle in order to return to your optimum. After it's all done, THEN you can reconnect your vacuum canister and enjoy your ride.

All this assumes that you're engine is set up correctly to start with --- i.e. fuel mixture is right, cooling system is in good shape, you don't have detonation problems, etc. --- so that you have the freedom to do all this. However, for example, if you're running too much compression and have detonation problems, you may not have the freedom to use the setting for best power and will be forced to use a more conservative setting.

Bear


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## 69 237 (Feb 18, 2018)

Thanks Bear. I don't think I have any rattling at 34degrees. I also had a typo above, the mechanical advance provides 26degrees. That would be 8 initial and 26 degrees mechanical for 34 total. Vacuum advance makes 44 total when hooked up. 

I'm probably not going to take it to the strip. I just want to cruise and have fun in the street. Is there going to be a noticeable difference 32 and 36 degrees total without vacuum advance? If not, I'll just be conservative and get my distributor recurved for 12 or so initial and 32 total.


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## 69 237 (Feb 18, 2018)

I've been trying to drive I and see if I can tune it. I set my timing to 10deg in drive without vacuum advance. I added vacuum advance for a total of 16 degrees at idle in drive. 

I noticed it shaky and running rough in park but not drive. We checked timing and it is 6 degrees lower in park, than it is in drive. It is 10deg initial in drive and 4 in park. How can this be?

I have done everything I can think of and it always is this way. I don't know how that can be with a standard distributor. I do not have amy thing that would retard the ignition. Any thoughts?


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## BearGFR (Aug 25, 2008)

69 237 said:


> I noticed it shaky and running rough in park but not drive. We checked timing and it is 6 degrees lower in park, than it is in drive. It is 10deg initial in drive and 4 in park. How can this be?


It shouldn't be --- but you said it runs smoother/better when in drive than in park, so I'm suspicious of a couple things: idle mixture being way off, such that when there's no load on the engine it's not running right. Perhaps very light springs on your advance mechanism - such that when it's in drive and running smooth(er), probably at a higher rpm than when in park, the rpm is enough to start activating some of the centrifugal advance. --- That could explain what you're seeing. --When you're seeing the difference, is the vacuum canister disconnected and the line to the carb/manifold plugged? If the line isn't plugged, you're creating a lean condition by letting in more air - that could be causing the roughness.

Bear


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## 69 237 (Feb 18, 2018)

The line is always plugged when vacuum advance is disconnected. 

The springs could be advancing at in park. I have springs that come in at 800rpms. My park idle is just above that, but drive is 700 or so. Would advancing cause it to run rough and lower timing? 

I've backed out the mixture screws, with the he car is drive, until the vacuum no longer increases (3 turns out on the quadrajet)


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## PontiacJim (Dec 29, 2012)

Here are your factory specs for your distributor if yours is still the original one - 350CI 2Bbl & automatic. This should give you a base line to work with.

Mechanical advance begins at 800 RPM
Mechanical advance @ 1950 RPM's - 13-17 degrees.
Maximum mechanical advance @ 4800 RPM - 22-26 degrees.

Vacuum Advance starts at 6-8 Hg inches
Maximum Advance 20 degrees @ 13-15 Hg inches

Factory Initial @ the crank is 9 degrees BTDC.

In comparison, here is the specs for the 350CI 4Bbl option (which is most likely the HO version) and automatic.

Mechanical advance begins at 850 RPM
Mechanical advance @ 1900 RPM's - 3-7 degrees.
Maximum mechanical advance @ 5100 RPM - 16-20 degrees.

Vacuum Advance starts at 8-10 Hg inches
Maximum Advance 20 degrees @ 15-17 Hg inches

Factory Initial @ the crank is 9 degrees BTDC.

Keep in mind that adding a non-factory hi-perf cam will effect engine idle quality & vacuum. You may need to raise your idle in Drive closer to 750-850 RPM's to keep vacuum up and the engine running smooth.


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## BearGFR (Aug 25, 2008)

69 237 said:


> ... The springs could be advancing at in park. I have springs that come in at 800rpms. My park idle is just above that, but drive is 700 or so. Would advancing cause it to run rough and lower timing? ...


That doesn't make sense to me, advance usually causes an engine to get happier.... Something else is going on. I'd recommend forgetting about timing for now and work on getting the best idle quality in park, no load, with that idle also being at the correct RPM (which means below the point where the centrifugal starts to come in.) It it helps, put on some heavier springs to make sure of that, even if only temporarily.

Bear


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## 69 237 (Feb 18, 2018)

I put the heaviest springs I had on and dialed it in to 13degs initial no vac advance. 21 with vac advance. Verified it was the same in park and drive. Rock steady when 150F. Ran great.

Drove it a decent amount and got it up to 195F. It was running rough. Checked timing and it was 32 or so with vac advance... I checked that the distributor was too tight to move.

Then if I put it in park, timing would drop timing to around 20degrees and not pick up advance when revved up to around 1500rpm. It behaved this way when I adjusted the timing back down as well. Idle speed was less than 800 in park.

I think my issue is that I have too much distributor gear end play. There is probably 3/32"-1/8" end play. I've ready that can cause variability. I'm thinking expansion, loads, and revving the motor cause the dist gear to ride up and down the cam gear.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> I put the heaviest springs I had on and dialed it in to 13degs initial no vac advance. 21 with vac advance. Verified it was the same in park and drive. Rock steady when 150F. Ran great.
> 
> Drove it a decent amount and got it up to 195F. It was running rough. Checked timing and it was 32 or so with vac advance... I checked that the distributor was too tight to move.
> 
> ...



At this point with all the inconsistencies in timing, I would spring for a new vacuum advance cannister.


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## 69 237 (Feb 18, 2018)

So I finally made more progress I have confirmed on 2 cooling cycles that the initial timing advances 12 degrees once the car is warmed up. I literally watched it hope with vacuum advamce unplugged.

This is after I changed dostributor main shafts to one to give me 16 degrees advance (I verified this). I also shimed the distributor gear to 0.014 thousands. 

The car runs great when it's warmed up enough to get the timing up to where it should be (it's starts at 4deg and warms up to 16) and vac advance makes it 30. Once it heat soaks after a long drive it runs like garbage. Cuts out at low rpm acceleration and seems like it wants to miss under load. It even cut out from a mild start and seem to die and start itself back up. If I let it sit and cool down its great all over again. The timing doesn't change after heat soak still at 16 without vac advance. No change between park or drive. 

Only when it's heat soaked it'll have lower timing in park than drive. It was still 30 in drive, and 24 in park. When revved, the timing goes down. 

This doesn't make since and I thought all would be fixed with replacing the main shaft and setting the endplay. Any thoughts on how or why this could occur?


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## PontiacJim (Dec 29, 2012)

Makes absolutely no sense. I can't see how your initial timing at the balancer would change from 4 degrees at cold start-up to 16 degrees when hot and vacuum disconnected. Initial timing should be 9 degrees.

Reading back through the posts, I think it is time to either send out the distributor to a shop that can set it up and/or dial it in and see if the distributor is the problem or get another distributor and start over.

Also, at this point, with all the timing degrees jumping all over the place, I would ditch the timing light and buy a new one because I don't think I would trust it.


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## 69 237 (Feb 18, 2018)

I pulled the plugs and they are showing lean barely tan at all. Seems like I may be chasing a lean condition. If I put my hand over the carb or close the choke a bit, it stalls instead of picking up. I would think that means it's spot on or a touch rich, right? 

I do have major exhaust leaks in the downpipes and a few after that. Could exhaust leaks cause it to run lean?


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## geeteeohguy (Feb 2, 2008)

It could very well be that your mechanical advance is sticking, caused by varnish and gum inside the distributor housing and on the shaft. I've had it happen. Pull the dist. cap off and turn the rotor by hand---it should snap back immediately when released. If not, that's your problem. The cure is to remove the distributor, take it apart, and remove the varnish from the shaft and clean the housing. You can also take this opportunity to re-install lube in the pocket at the upper end of the housing, which is only accessible with the dist. shaft removed.


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## BearGFR (Aug 25, 2008)

I'm wondering if the vacuum canister is bad, or maybe even if the linkage rod has rusted in two or something - such that it's allowing the breaker plate to 'freewheel' and get drug around by the shaft rotation? I'm assuming you've checked and made sure the linkage rod is connected properly.. For the advance to be dancing around like that, SOMETHING has to be moving in ways it's not supposed to.

Bear


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## PontiacJim (Dec 29, 2012)

Not sure why you are tackling the plugs and looking into lean/rich running when you have not gotten the timing issues fixed? Or have you?

Since you pulled the distributor out to shim the end-play and you installed another shaft limiting the mechanical advance to 16 degrees, I can only assume that you checked all movement operations of the plate, advance can, and mechanical advance weights - watched the mechanic weights move/advance freely and used a hand held vacuum pump to test vacuum movement of the vacuum can/arm/distributor plate. Assume the bushing at the top of the shaft was tight and not sloppy. Short black wire was correctly attached to distributor advance plate and tested for continuity/ground. Checked grounding of distrib to engine and distrib to car body. No slop in rotor button to effect timing.

Dwell Meter does not fluctuate with engine running cold/hot? 

You stated the engine timing changes when warmed up. Engine temps should have no effect on initial timing - all things equal - or when warmed up.

So if it is not a distributor issue and each function of the distributor is known to work as it should and end-play and shaft play are within spec, then it has to be something else.

You stated you have manifold vacuum, so no temperature "vacuum tree" to effect timing once warmed up.

So what's left:

Distributor gear is being jammed down onto the cam gear and has no play. 

What viscosity oil are you using. Oil is thicker when cold and thins out as it gets to temp. What is the oil pressure cold and when warmed up at the time timing changes?

Last oil filter/oil change? Good brand oil filter?

Camshaft end play is excessive. As the cam moves forward and backward, it can advance or retard the distributor timing (this could change when oil is cold/thick and hot/thin). The cam thrust plate could be worn, cam's distributor gear worn (assume new gear on distributor installed when you disassembled), timing chain/gears not correctly aligned or loose and could be causing some forward/backward movement of the cam.

Harmonic balancer torqued to spec?

Oil pump failing. If the check ball is sticking or gears failing, the pump will not spin smoothly and you could have a momentary sticking or hard resistance from the pump which could then have an effect on the oil pump shaft and distributor timing, especially if:

Oil pump shaft is worn, cracked, or possibly have a broken "ear". 

The oil pump pick-up could be plugged causing erratic oil pump/pressure fluctuations.

So if the distributor checked out and nothing seems in error or worn, then I would start looking at engine mechanical problems related to distributor/engine timing. :thumbsup:


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## 69 237 (Feb 18, 2018)

PontiacJim said:


> Not sure why you are tackling the plugs and looking into lean/rich running when you have not gotten the timing issues fixed? Or have you?
> 
> - it's consistently starting cold at 8 degrees and is 16 degrees when warm. I verified with another timing light.
> 
> ...


I'm not really sure what's causing this. Maybe my answers in the quote above may reveal a clue. I really appreciate your time and detail. 

For what it's worth I changed to colder plugs RS43S and it made a big difference. It has more power and seems to take gas better. Besides sorting the timing change, it really just needs part throttle tuning.


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## 69 237 (Feb 18, 2018)

My advance springs were the cause of the change in time between park and drive. I ended up changing thechanging the springs out. Now it has 13degs initial in dirve and park when fully heat soaked. The distrbutor shows a maximum possible 9-10 degrees dostributor mechanical adavnce. That'll puts me at 31-33 total amd 12 more vacuum advance that comes all in at 12inhg for a total cruise of 43-45total. 

I tuned the carb in until it leaned dropped and backed them out a full turn. It will chirp tires landing into second at 3000rpm now. The plugs show up really light at idle.They look white, but if you put them next to new plugs they look barely off white. If I give it any more gas at idle it bog and gets erratic so I think it must be ok. Maybe that's just the ethanol shell v power gas cleaning them off good?


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## PontiacJim (Dec 29, 2012)

69 237 said:


> My advance springs were the cause of the change in time between park and drive. I ended up changing thechanging the springs out. Now it has 13degs initial in dirve and park when fully heat soaked. The distrbutor shows a maximum possible 9-10 degrees dostributor mechanical adavnce. That'll puts me at 31-33 total amd 12 more vacuum advance that comes all in at 12inhg for a total cruise of 43-45total.
> 
> I tuned the carb in until it leaned dropped and backed them out a full turn. It will chirp tires landing into second at 3000rpm now. The plugs show up really light at idle.They look white, but if you put them next to new plugs they look barely off white. If I give it any more gas at idle it bog and gets erratic so I think it must be ok. Maybe that's just the ethanol shell v power gas cleaning them off good?



Sounds like you got it - numbers look good. Hard to read plugs with the ethanol unleaded, not like the "old days" so I would not worry too much. As long as you are not hearing any "pinging" from the engine under hard acceleration, you should be good.


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## 69 237 (Feb 18, 2018)

Thanks for your time and guidance through this!

I will say that it does bother me because it wants to heat up to 230F after I shut it off. Is that normal? It was 90F yesterday though. It idles around 195-200F and cruises between 180-200f depending speed 55-70 (2600-2800rpm)


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## BearGFR (Aug 25, 2008)

It's not unusual for them to get a little warmer after shutdown. The coolant stops circulating so it can't transfer any heat away from the engine. If you re-start it, does it cool back down to where it was fairly quickly?

Bear


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## 69 237 (Feb 18, 2018)

Within a couple of seconds it's down to 215F and then back down to 195-200 in 20 seconds or so.


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## BearGFR (Aug 25, 2008)

69 237 said:


> Within a couple of seconds it's down to 215F and then back down to 195-200 in 20 seconds or so.


Yeah, I wouldn't worry about it then. Sounds good to me.


Bear


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## PontiacJim (Dec 29, 2012)

BearGFR said:


> Yeah, I wouldn't worry about it then. Sounds good to me.
> 
> 
> Bear


X2 - Normal.:thumbsup:


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## 69 237 (Feb 18, 2018)

The only atypical observation I have is changing ignition timing. When cold it sits at 3 degrees without vac advance and when its heat soaked it goes to 13 without vac advance and stays steady park to drive. 

I changed literally every part on the distributor with no change. I even swapped the distributor out. Distributor end play is 0.014" so that shouldn't be it. 

Since the timing is steady and predicatable when hot, I haven't been concerned about it, but it doesn't make it easy to start when cold.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> The only atypical observation I have is changing ignition timing. When cold it sits at 3 degrees without vac advance and when its heat soaked it goes to 13 without vac advance and stays steady park to drive.
> 
> I changed literally every part on the distributor with no change. I even swapped the distributor out. Distributor end play is 0.014" so that shouldn't be it.
> 
> Since the timing is steady and predicatable when hot, I haven't been concerned about it, but it doesn't make it easy to start when cold.


Its probably due to the rotational twist in the crankshaft steel based on its molecular structure. When it's hot it expands in a clockwise rotation and when it cold, it cools down and unwinds in a counter-clockwise direction. If you foot brake the car or use a line-lock to do a wicked burn out, your timing will probably be north of 60 degrees until you get rolling - those Pontiac crankshafts are really springy.

Could be related to where you have the vacuum line hooked up at the carb - possibly the choke position as well? Could also be a sloppy timing chain, worn distributor gear, worn cam gear. Getting the end play to .014" won't compensate for worn gears if that is the problem - and you can test for a sloppy timing chain/gears. YouTube has a video that shows this.

At 3 degrees Initial, it may be too retarded to fire up well. I would test this by checking it cold as you described @ 3 degrees and immediately move/adjust the timing to get 12 degrees. Shut the car off the minute you see 12 degrees and then fire it up - still being cold, and see if it fires up any better. 

Next test would be to plug the vacuum line directly into a manifold vacuum source for full vacuum. You timing should jump up about 16-20 degrees from whatever you have it set at the balancer. If it does not, then you have a faulty vacuum advance or distributor problem.


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## 69 237 (Feb 18, 2018)

The information on the crankshaft is really interesting. I'm wondering if that has something to do with it. I have a brand new comp double roller timing chain set. When I adjusted my valve timing a couple months back the chain had zero slop on right side. 

The cam gear is good and the distributor gear is just now starting to get a wear pattern to show. I thought maybe I had can thrust issues, but I thought that would cause a timing shift when loading the motor from park to drive. Timing is steady shifting from park to drive though. 

I know the vac advance is good I've verified it hot and cold. I know it'll start up great if I move the timing up to 12 when cold, it'll just really run wicked with the 22 or so initial when heat soaked.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> The information on the crankshaft is really interesting. I'm wondering if that has something to do with it. I have a brand new comp double roller timing chain set. When I adjusted my valve timing a couple months back the chain had zero slop on right side.
> 
> The cam gear is good and the distributor gear is just now starting to get a wear pattern to show. I thought maybe I had can thrust issues, but I thought that would cause a timing shift when loading the motor from park to drive. Timing is steady shifting from park to drive though.
> 
> I know the vac advance is good I've verified it hot and cold. I know it'll start up great if I move the timing up to 12 when cold, it'll just really run wicked with the 22 or so initial when heat soaked.



Almost sounds like the vacuum advance may be slow to engage and slow to retract, versus instant action. I get you verified it hot/cold, but have you ever pulled the distributor cap & applied vacuum and then removed vacuum to see how fast the arm that pulls the points plate operates? Could even be the plate sticking or binding.

Just make sure you keep the mechanical total advance, Initial plus distributor's mechanical around 32 degrees. As you start going past that, that's where you can get into detonation/pinging problems. And, you also don't want total advance - mechanical plus vacuum advance - to be any more than about 52 degrees. 

PS: Only goofing on the crankshaft, just using sarcastic humor - Northern style. But it could be a stretched or looses chain, worn gears, or possibly the cam moving back & forth just a hair which could affect the meshing of the distributor gears at the rear of the cam.

I guess if it runs good, just accept it. You will know what the true problem is when it breaks. Otherwise you could be guessing & adjusting for the rest of your life or end up in the Pontiac ward at the insane asylum. :thumbsup:


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## 69 237 (Feb 18, 2018)

Makes sense haha. I've check vacuum advance with a vac pump when cold. It comes in at 7 inhg and is fully in at 12inhg. When released it returns the arm dn point plate almost instantaneously.

Since it only retards the timing when cold it seems like it's a conservative issue that I can't see any issues coming from.. especially since it's rock steady when warm and isn't jumping around. Timing set isn't worn or stretched and the gears are fine too. I'm just going to drive it.


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## 69 237 (Feb 18, 2018)

I took it out for an extended cruise. It did ok, but I could tell the 90 degree temps were getting to it. When I got back home it was up to 200-205. I revved it to 1800-2000 in neutral to cool it down and poped the throttle just a touch and a rocker stud broke clean at the threads.

Is it odd for a rocker stud to just break? They came woth heads so I don't know what condition they were in, but they may have been put through the ringer.


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## My65goat (Jul 26, 2017)

69 237 said:


> I took it out for an extended cruise. It did ok, but I could tell the 90 degree temps were getting to it. When I got back home it was up to 200-205. I revved it to 1800-2000 in neutral to cool it down and poped the throttle just a touch and a rocker stud broke clean at the threads.
> 
> Is it odd for a rocker stud to just break? They came woth heads so I don't know what condition they were in, but they may have been put through the ringer.


Yikes. ...I hope that they are screw in studs? Hopefully if they are you can get the snapped stud out otherwise you will be pulling the heads....


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## PontiacJim (Dec 29, 2012)

69 237 said:


> I took it out for an extended cruise. It did ok, but I could tell the 90 degree temps were getting to it. When I got back home it was up to 200-205. I revved it to 1800-2000 in neutral to cool it down and poped the throttle just a touch and a rocker stud broke clean at the threads.
> 
> Is it odd for a rocker stud to just break? They came woth heads so I don't know what condition they were in, but they may have been put through the ringer.


They don't normally break if using a stock grind cam. Going with a bigger cam/more valve spring pressures could fatigue the rocker arm stud or be too much pressure. 

With screw-in studs, the weak "bottle neck" transition from 7/16" to 3/8" is why most will change out to the stronger Big Block 7/16" studs and poly-locks when going to bigger cams.

The next thing to check is if you went with a higher lift cam, the factory rocker arm slot that pivots on the rocker stud may hit and bind against the rocker arm stud and snap it off. The aftermarket stamped steel 1.52 rocker arms have the needed rocker arm slot for higher lift cams.

It is possible your rocker arm geometry is off adding extra side loading of the rocker arm stud. Don't know if you checked the wear pattern on the valve stem top when you rebuilt the engine.

If it is a press-in stud, then you want a machine shop to replace it - but better yet, add the screw-in rocker arm studs in place of the press-in studs since you will have to pull the head and while at it, do the other side to match IF you feel the heads are worth it.

The other reasons for the stud breaking may be that you have a bent valve or one that is sticking because the clearances/tolerances of the valve stem to valve guide is too tight, but I would suspect you might have a bent pushrod to confirm this. So if you are not using a big lift cam and your rocker arms are not binding, then I might consider a bent or "tight" valve. I would not suspect your valve hitting the top of the piston unless something was way off.

It may just be "one of those things" or you have a problem that you need to figure out so it does not do it again. :thumbsup:


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## deputycrawford (Jan 16, 2010)

I have not read every single thing on this thread but I want to tell everyone about a little trick I learned. To check for vacuum leaks without spraying chemicals all over your engine, turn on a propane gas torch without lighting it. Run it over the area you want to check. If the engine revs up then it used the gas you put near it. You keep and clean engine and you don't rent a smoke machine. Just saying. 

Jerry


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## 69 237 (Feb 18, 2018)

The valve stem wear pattern look's a little odd. It's in the center, but the there's an angled edge and the contact don't go completely across the valve stem and the bottom of the wear pattern it does go all the way and cross at the top. 
There's no binding, but the stud was beat up from the previous owner. I replaced the stud and it's running fine now.
The cam isn't crazy. Similar profile to the 068 cam but only 270 duration and max lift of around 0.450".

Thanks for the suggestion on using propane to find leaks. I actually used that trick and found nothing. I also made a smoke machine that had the same result.


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## 69 237 (Feb 18, 2018)

For resolution of this post, I got tired of fighting what seemed like multiple issues at once.

I ordered a DUI HEI and fed it using a relay to give it full battery voltage with no risk of using old wiring. I set timing at 15 initial and 35 total, 48 with vac advance.

I then went through the quadrajet and respeced everything. I raised float to 1/4, adjust secondary hangers, and verified power piston hanger height. I gained full mixture screw control. Now it idles smooth (15inHg at 650rpm), starts up with 2 pumps when dead cold, and transitions through all circuits well besides the secondary engagement. I'm tweaking the air valve spring in steps.

Thanks for the help!


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## HiVolts (Jan 27, 2020)

Lots of good info here. Awesome stuff PontiacJim. 

I just recently replaced a corroded not advancing MSD.

Mine seems to run best at 15 initial with 21 degree max advance to 36. I also have all in 36 at 2300 rpm. This is what Butler recommended. Mine is all mechanical, no vacuum connected to distributor. 

69 237 - Not understanding what you mean by 48 with vac advance??


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## 69 237 (Feb 18, 2018)

I have 13 degrees of vacuum advance so I have 35degrees total timing at 3000rpms and up under WOT. At cruise over 3000rpms I have 48 with vacuum advance.


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## 69 237 (Feb 18, 2018)

To follow up on this thread and provide more resolution, I installed a 3200rpm torque converter from PTC and it helped a ton.

My idle went from 1050rpm in park clunking to 700rpm or so in drive to smoothly dropping 100rpm (800 or so to 700). My manifold vacuum also increased to 16.5inHg. The stock 13inch converter was lugging this combination too much.


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## BearGFR (Aug 25, 2008)

69 237 said:


> I'm tweaking the air valve spring in steps.


Why? That's the wrong way to tune the 'bog' out of a QJet... Control the air valve opening rate with the vacuum diaphragm, not spring tension. 

Bear


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## 69 237 (Feb 18, 2018)

Already did that first. I replaced a diaphragm that only opened at WOT... made a custom restriction to get a good pull off speed. The car likes the air valve tension tweaked 1/8 tighter when its cold out vs warm for a 3/4-7/8 turn range which is spot on where it should be.


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## 69 237 (Feb 18, 2018)

Spring is upon us and I'm getting the car ready for another season. Ive got a few other threads that you've helped with and most of the issues have worked out through tuning, or replacing parts for ones better suited for the combination.

One issue that is still present is the weird timing when cold (only being a few degrees when cold and advancing when hot).

As mentioned above I have a new DUI HEI distributor that does this same as the old points one. Verified that it happens with or without vac advance.

Going back to previous questions. Oil pressure is good. I use driven 15w50 and keep roughly 25psi at 725rpm idle and am at 55psi or so around 2100rpm. The engine was built for thicker oil. Oil pump is a blueprinted butler pump. The one thing to note is that the oil pump driveshaft ears aren't present. The distributor could only change timing with how much end play it has, right? The new distributor has acceptable end play so that should only allow for a few degrees of variation at best.


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