# New MSD Ready-to-run, need help with timing curve



## ragtopgoat (Sep 26, 2019)

I just replaced my stock points dizzy with a MSD R2R on my stock 389 (‘66 GTO with tripower) and set the curve to be all in at 3500. I’m using the silver bushing that limits the total to 25 and set the initial at 10. On a test drive (75 degree day), I am getting pinging at WOT. I think my initial and total timing should be right, so maybe I need go to heavier springs to up the RPM for total timing? Looking for some advice here. I’ve attached some images of the timing curve from the MSD manual, I have the light blue springs in now, and I’m thinking is going to the next level with heavy silver and light silver springs, which would bring total timing in at 4000 RPM. 
With the stock dizzy I did not have any pinging.


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## ragtopgoat (Sep 26, 2019)

I should have noted, I am running vacuum advance with manifold vacuum. It adds 10 degrees under vacuum.


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## BearGFR (Aug 25, 2008)

There won't be any vacuum present at WOT. If it didn't ping with your previous setup, then "slowing down" the curve with heavier springs sounds reasonable. Which heads are you running and do you know what your compression ratio is? Another possibility: go to smaller bushing so that the dizz has 29 degrees of travel and back your initial off to 6. You'll still be at 35 when it's all in. You could also back it down to 32-33 total without changing anything inside just to see if that's enough to get rid of the ping. 

Bear


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## armyadarkness (Dec 7, 2020)

I just installed the same dizzy and I love it! I don't recall what setup I ran, but I left the limiter bushing as stock, and then set my base so that the total would be 36. Don't consider the vac can in the total equation, but I did set the vac can to give 10 degrees at full draw, connected to full manifold.

If some one else doesn't give you better advice, I can look in and see what else I did, however, I have a full roller 400 with 670 heads and an edelbrock intake with an 850 edelbrock carb, so we wouldn't be the same anyway.

If you're sure that your total timing is the same as it was on the points dizzy, then I'd replace ONLY ONE spring with a heavier one, and that will bump your curve up to the next stage.


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## Lemans guy (Oct 14, 2014)

Agree with Bear and Army. If you are pinging AT wot.....then the springs are not the problem since WOT is way beyond 3000 RPM.....

so dial back the base 2 degrees and do a test drive. If still pinging dial back 2 more degrees and test drive.....You want it just below where it will not ping..

now if it is pinging on the acceleration, the ramp up to 3000 RPM, the springs are too light. Army is correct change out one stronger spring, and go with one light and one medium.

also you did not do anything wrong. I have found those charts have a little swag in them as does the bushings that 25 could be 27 or 28 and the springs are not going to be-exactly 3000 either...once on the car you need to verify the numbers with a timing light....

Your vac advance is right 10 degrees at full manifold leave that. That also helps tremendously if you have to dial your base back a couple degrees.

Good luck let us know how you do


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## ragtopgoat (Sep 26, 2019)

BearGFR said:


> There won't be any vacuum present at WOT. If it didn't ping with your previous setup, then "slowing down" the curve with heavier springs sounds reasonable. Which heads are you running and do you know what your compression ratio is? Another possibility: go to smaller bushing so that the dizz has 29 degrees of travel and back your initial off to 6. You'll still be at 35 when it's all in. You could also back it down to 32-33 total without changing anything inside just to see if that's enough to get rid of the ping.
> 
> Bear


I am not sure which specific heads I have, the previous owner had the heads replaced, which is noted on the invoice as "Correct Pontiac Heads". My assumption is that they are stock with stock compression. Is there a way to ID the heads from numbers visible on the sides? 

I'll try backing my initial timing off to six and see if that makes a difference. If not, slowing down the total timing with heavier springs will be my next step.


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## Lemans guy (Oct 14, 2014)

Overall the majority of dizzy’s I do need one light and one medium spring, rarely get two the same, sometimes it happens. But mostly the combination of various springs get it where you want it.


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## ragtopgoat (Sep 26, 2019)

Lemans guy said:


> Agree with Bear and Army. If you are pinging AT wot.....then the springs are not the problem since WOT is way beyond 3000 RPM.....
> 
> so dial back the base 2 degrees and do a test drive. If still pinging dial back 2 more degrees and test drive.....You want it just below where it will not ping..
> 
> ...


Thanks for your response. I did test the engine at different RPMs and ramping up toward 3000, 4000 and when I wasn't at full throttle, I did not get pinging. It was specifically when I put my foot in at WOT, opening up the tripower secondaries (full engine load) that I could hear sustained pinging.


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## armyadarkness (Dec 7, 2020)

ragtopgoat said:


> I am not sure which specific heads I have, the previous owner had the heads replaced, which is noted on the invoice as "Correct Pontiac Heads". My assumption is that they are stock with stock compression. Is there a way to ID the heads from numbers visible on the sides?
> 
> I'll try backing my initial timing off to six and see if that makes a difference. If not, slowing down the total timing with heavier springs will be my next step.


Maybe I missed something... 6? Your base should be around 12. Also, if your ping is only at WOT; what is your RPM when you notice the ping? What trans do you have? I have a TH400 and the kick down switch was failing... So when I stomped on it at 50MPH, it never down shifted. The result was a wide open 850 CFM carb, dumping too much air and fuel into an engine at 2500 and it rattled all over the place. If you nail it from take off and run through the gears, will it still ping? or only at roll ons in top gear?


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## ragtopgoat (Sep 26, 2019)

armyadarkness said:


> Maybe I missed something... 6? Your base should be around 12. Also, if your ping is only at WOT; what is your RPM when you notice the ping? What trans do you have? I have a TH400 and the kick down switch was failing... So when I stomped on it at 50MPH, it never down shifted. The result was a wide open 850 CFM carb, dumping too much air and fuel into an engine at 2500 and it rattled all over the place. If you nail it from take off and run through the gears, will it still ping? or only at roll ons in top gear?


I was responding to BearGFR, who suggested backing off my initial timing to see where the pinging stopped. If I set it at 6 initial, which would give me ~31 total, if that stops the pinging, then I can work from there. I don't think I need anything more than 10 initial and would rather keep it in the 8-10 range. I have vacuum advance, so with 8 initial, I'll have 18 at idle and part throttle.


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## ragtopgoat (Sep 26, 2019)

ragtopgoat said:


> I was responding to BearGFR, who suggested backing off my initial timing to see where the pinging stopped. If I set it at 6 initial, which would give me ~31 total, if that stops the pinging, then I can work from there. I don't think I need anything more than 10 initial and would rather keep it in the 8-10 range. I have vacuum advance, so with 8 initial, I'll have 18 at idle and part throttle.


Also, the car is a 4-speed manual. The pinging would show up from 3000 and up, when I put my foot in to it. I don't have a more detailed map of RPM and when the pinging would hit, as driving on the street and flooring this car on a busy Sunday afternoon made it challenging to watch the tachometer as I'm blasting down the highway!


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## armyadarkness (Dec 7, 2020)

ragtopgoat said:


> I was responding to BearGFR, who suggested backing off my initial timing to see where the pinging stopped. If I set it at 6 initial, which would give me ~31 total, if that stops the pinging, then I can work from there. I don't think I need anything more than 10 initial and would rather keep it in the 8-10 range. I have vacuum advance, so with 8 initial, I'll have 18 at idle and part throttle.


Got it. Most will recommend 12 initial and then 10 at the can, to provide over 20 degrees for idle and light cruise... but I'll let everyone else advise on it.


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## armyadarkness (Dec 7, 2020)

ragtopgoat said:


> Also, the car is a 4-speed manual. The pinging would show up from 3000 and up, when I put my foot in to it. I don't have a more detailed map of RPM and when the pinging would hit, as driving on the street and flooring this car on a busy Sunday afternoon made it challenging to watch the tachometer as I'm blasting down the highway!


Im right there with you. I just wanted to rule out the kickdown switch.


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## ragtopgoat (Sep 26, 2019)

ragtopgoat said:


> I am not sure which specific heads I have, the previous owner had the heads replaced, which is noted on the invoice as "Correct Pontiac Heads". My assumption is that they are stock with stock compression. Is there a way to ID the heads from numbers visible on the sides?


I did some checks on the heads, and if I understand correctly, the casting number shows "13", which according to the appendix in the "_How to Rebuild Pontiac v-8s" _book, the heads are a 1970 head with a compression ratio of 10.25:1. Here's a picture of the passenger side head (both heads have the same casting number):


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## Lemans guy (Oct 14, 2014)

18 initial will be fine,...main thing is to elimiate the pinging which at WOT should be beyond 3000 RPM’s where your springs become irrelevant....once they reach mechanical limit....you get the 25 degrees Centrifigal all the way up to 8000 RPM....

and your foot elimates the 10 degrees Vacumn advance...so your pinging is the base + Centrifigal = 35.....now that is based on the charts and not your timing light.

like I said that 25 may really be 28.....so it pays to check and no and then you can adjust it. As needed by either changing the bushing and dialing up the base or leaving the bushing and dialing down the base.....


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## PontiacJim (Dec 29, 2012)

ragtopgoat said:


> Thanks for your response. I did test the engine at different RPMs and ramping up toward 3000, 4000 and when I wasn't at full throttle, I did not get pinging. It was specifically when I put my foot in at WOT, opening up the tripower secondaries (full engine load) that I could hear sustained pinging.


It pings because the engine is under load at WOT, ie it's really grunting. Gear ratio can play a big role in "pinging.". Example, 3.08's would be horrible because the engine really has to lug on those gears. 4.33's would be great because the engine is going to ramp the car up real fast. So at cruising speeds, and less than WOT, your timing may be OK, but once you lug the engine down, you get the pinging.

I would keep my Initial at 10, but limit total to 32, so a stop bushing that limits mechanical to 22 degrees may be better, OR 12 Initial and 20 mechanical. So with Initial at 10, or 12, vacuum advance will pull in another 10, for 20 or 22 degrees which should be OK. The key is easy starting and if the starter labors to crank the engine over, then the Initial is too much and needs to be backed off.

I did not see a mention of octane being used? No. 13 heads show up as 1970 heads which you can confirm by the cast date code found below the valve cover towards the back of the head on the drivers side head. The head shows to be a 10.0 compression. Being a 389, I can only assume the engine has been bored .060" over and 400CI pistons used to match the later heads?

Cam choice is important. A cam can add more cylinder pressure to the already 10.0 compression - which is not what you want. Yet another cam can bleed off compression - which you may want. So what cam is in the engine, specs?

IF the engine has 10.0 compression, you WILL NOT get the pinging out if using pump gas. The octane will not be enough alone and will require an octane booster or high octane racing gas mix.

That said, in my opinion, a little more info on engine specs could be used. If the engine ran fine with no pinging prior to the distributor installation, then you should be able to tune the pinging out which may take a little trial & error.

Other contributors to pinging are engine temps/cooling. A cooler running engine will have less of a tendency to ping.


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## ragtopgoat (Sep 26, 2019)

PontiacJim said:


> It pings because the engine is under load at WOT, ie it's really grunting. Gear ratio can play a big role in "pinging.". Example, 3.08's would be horrible because the engine really has to lug on those gears. 4.33's would be great because the engine is going to ramp the car up real fast. So at cruising speeds, and less than WOT, your timing may be OK, but once you lug the engine down, you get the pinging.
> 
> I would keep my Initial at 10, but limit total to 32, so a stop bushing that limits mechanical to 22 degrees may be better, OR 12 Initial and 20 mechanical. So with Initial at 10, or 12, vacuum advance will pull in another 10, for 20 or 22 degrees which should be OK. The key is easy starting and if the starter labors to crank the engine over, then the Initial is too much and needs to be backed off.
> 
> ...


Lots of good questions here! 

The rear end ratio is 3.55:1
I am running 91 pump octane, trying to avoid requiring race gas as this is a car for top-down cruises and not racing. But who can resist an occasional full-throttle romp!
The heads do show a date stamps from 1970 (E260 and F050). The engine is bored 60 over, but whether the pistons match the heads, I'm not sure. Would it run if they didn't? The previous owner's mechanic who installed the heads should have known that. Picture of the pistons with the heads removed below.
I believe the cam is stock, but that's mostly an assumption
As I previously mentioned, with the stock dizzy, I never noticed pinging, whereas now with the MSD R2R installed, I can clearly hear pinging at WOT. So my goal is to tune the engine to run on 91 octane street gas. Clearly I need to continue to adjust until I eliminate the ping. I'm going to get some accurate advance numbers with my timing light too
The engine has a 160 degree thermostat and never, ever goes above 160 degrees, both on the dash gauge and by testing the radiator with an infrared pyrometer. Yesterday when I was getting pinging the ambient temps were mid-70's. I kept a close eye on the temp gauge and it never budged

Picture of the pistons with the heads removed:


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## PontiacJim (Dec 29, 2012)

ragtopgoat said:


> Lots of good questions here!
> 
> The rear end ratio is 3.55:1
> I am running 91 pump octane, trying to avoid requiring race gas as this is a car for top-down cruises and not racing. But who can resist an occasional full-throttle romp!
> ...


OK, looks like the pistons are indeed 389, .060" over due to the placement of the valve reliefs. So, here's the scoop.

The Pontiac closed chamber 389 heads used smaller valves, different valve placement, press-in rocker arm studs, and used different scallops in the top of the bores for valve flow. The valves are placed at a 22 degree angle to the piston.

The 1967 400CI head was the last of the closed chamber heads ('68 and up are open chamber), but had the 1967 & up 2.11" intake valves & 1.77" exhaust valves, along with screw-in studs. The valves were spaced farther apart due to sizing and are placed at a 14 degree angle to the piston.

See Pic #1 & #2.

Because the valves are larger, spaced further apart, and at a different angle than the 1966 and earlier pistons - the valve reliefs in the top of the pistons are different. This means that the earlier 389 should be bored .060" and standard size 400CI pistons used having the correct valve relief placement to match the later 1967 & up heads.

Can you use the later heads on the 389 pistons? Yes, but lift and duration of the cam has to be kept reasonable so the valves do not hit the cylinder wall due to the mismatch of the valve clearance scallop found at the top of the cylinder bore, and so they do not kiss the pistons. From what I have read of others suggestions, it seems under .450"-.460" lift and duration at 270-280 degrees. I have no actual hands on experience, so cannot confirm this. The BEST way of course is to measure the clearance between the valve and piston, and maybe even a bore scope to view a valve to see how close it comes to the cylinder wall at max lift of the cam.

It is also pointed out that the later heads on the earlier 389 require the later 400CI pushrods for correct pushrod geometry - they are longer. This can be checked easily with the engine assembled and valve cover off. You can find several how-to examples doing a search through the forums.

Picture #3 are the 389 piston on left and 400 piston on right.

The #13 head is 72cc's but more like 75cc's in reality. With the flat top piston, this will put you at near 10.0 compression, maybe a tad lower. Again, at this compression, you will be hard pressed to tune out the pinging on pump gas. The previous distributor may not have been quite as accurate/functional as the new one. I went through this with another member with a 1970 GTO and he made a bunch of changes playing with the timing/curve to include a cam change looking to bleed off some cylinder compression. He got most of the pinging out at WOT, but did have to suppliment his gas with an octane additive.

Your engine temps look good like I like to run - my opinion/choice. You can try to get your total in at around 4,000 RPM's which may help bring the total timing in later as the curve rises. You may try dropping down to 32, then 30 total, but I still like the 10-12 initial, but of course you can try dropping down to 8 Initial and see how much that drops total to get it nearer the 32/30.

The next problem we will all see is your total timing with the vacuum advance of 10 degrees. Not enough. You want timing to be nearer 50 degree when the vacuum advance is at peak, ie max engine vacuum. This provides engine cooling and better gas mileage. So IF you had for example your total timing coming in at 32 degrees @ 4,000 RPM's and you let off the gas providing max engine vacuum, the additional 10 degrees from the vacuum advance will only put you at 42 degrees. This is a little shy of the preferred 50 degrees. Keep in mind this is at max engine vacuum when you completely lift off the gas - but will vary as not to often you are completely off the gas pedal. Cruising around town/highway you work the gas pedal so engine vacuum changes constantly.

So when you change one aspect of the timing and its curve, you also can change another setting - so all these need to be matched to one another. You can purchase different vacuum cans having different amounts of degree changes, or even use a stop if needed. Just takes some work and that trial and error out on the road testing.

Another thing to consider is if the carbs are running lean, or leaning out on a good pull. It is better to run richer, than leaner, as richer can cool the air/fuel mixture charge even thought it may indeed use a little more gas. I am not talking excessive, just a little richer. It is said that the ethanol laced gas needs to be run around 2 jet sizes more that factory. Spark plugs may tell you this. You can also play with spark plugs and run 1 set colder, but this rarely helps. You don't want to go too cold and have plug fouling - so confirm you are using the correct type plug and heat range. I also like to keep the gap .032"-.035" regardless of what other say. Tighter gap means less energy to fire. If you use a higher output coil, maybe go .040" on the gap. I like the MSD 6 type boxes as they do do the job, but if trying to keep the original look, it'll be out of place.

3.55's are a good gear, so I think that'll work.

So that should give you a little food for thought. If more questions, just ask away.


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## Lemans guy (Oct 14, 2014)

This is so well written and such a great assessment of the many issues discussed. Super Assessment PJ. PJ hit the keys, timing, octane, compression issues, heat.

sounds like you got the Heat beat! I too like to run cool 160 thermostat and keep it cool with good PCV to bring out the vapors condensation instead of totally relying on getting it hot to burn them off as some believe.

To build on what PJ said I try to set timing vacumn + total at 46. In the sixties 52 to 54 was good for the gasoline formulations of the day but now on that lean burn 46 or 48 is what I shoot for.

I think you need more octane than 91. At least 93 and with an octane boost probably, and perfect timing. 10% ethanol pump gas has more octane than pure gas,...pure gas a little more power. But not that noticeable if it is all tuned correct. I use 10% 93 octane ethanol pump gas on 9.5 compression, because of shear availability.

you have to use a timing like to nail down your Centrifigal timing and than adjust it. You have lot’s of leeway on idle timing. Large cams with high lift can take more idle timing. The mixture is lean from reversion so even 18 base and 10 vac for 28 can run great.

you may want to try one down bushing to drop that Centrifigal below 25 go to 22 or even 18 because it will give you more adjustability on the base and still keep the idle timing in a great place. Although 18 will work fine with a big cam 260? Lift higher idle timing can make it smoother and cooler.

get that timing light out, consider 93 octane, pure or 10%, and an octane booster.

and the reread PJ’s notes, you would have to pay a lot of money for that assessment!


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## ragtopgoat (Sep 26, 2019)

Thanks PJ for the excellent write up! I've re-read it a few times, as it is so packed with details. LeMans Guy and others have suggested 93 octane or octane boost. There is a gas station near me that has 100 octane at the pump, which is fine for local drives, but not helpful for road trips. In CA, the highest octane at the pump is 91. Other than blending a higher octane fuel, has anyone found an octane boost product that actually works? In years past, most of those products could barely affect the octane at all.


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## armyadarkness (Dec 7, 2020)

VP and Royal Purple get good reviews, but I've not tried either


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## michaelfind (Dec 14, 2018)

ragtopgoat said:


> Thanks PJ for the excellent write up! I've re-read it a few times, as it is so packed with details. LeMans Guy and others have suggested 93 octane or octane boost. There is a gas station near me that has 100 octane at the pump, which is fine for local drives, but not helpful for road trips. In CA, the highest octane at the pump is 91. Other than blending a higher octane fuel, has anyone found an octane boost product that actually works? In years past, most of those products could barely affect the octane at all.


Octane Supreme. Be careful with it because it is real lead. May not even be legal in California. I used to live there and realize there is a huge burden of extra regulations over your head.


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## Lemans guy (Oct 14, 2014)

I use Redline S1 Complete fuel system cleaner regularly, as a maintenance dose. It keeps the whole file system clean and the carriers for the Techron in it are an Octane Booster and an upper cylinder lubricant. All good things.

However it is not likely to have as much octane as products significantly designed just for that. You might have to research a little more to find the octane boost product you want, but with 91 gas and 10.0 compression you will need some and timing Set right as we were discussing. You will get there.


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## BearGFR (Aug 25, 2008)

ragtopgoat said:


> Lots of good questions here!
> 
> The rear end ratio is 3.55:1
> I am running 91 pump octane, trying to avoid requiring race gas as this is a car for top-down cruises and not racing. But who can resist an occasional full-throttle romp!
> ...


Alrighty - that's information to work with - I still have to make some assumptions on some dimensions, namely:
Head gasket bore size and compressed thickness - Nominal dimensions are .042-.045 compressed and these days commonly have a bore size of 4.300
Piston deck clearance (Pontiacs are "usually" around 0.015 "down" unless the block has been zero decked)
Head chamber volume - "nominal" for those heads (year model 1970 so they're open chamber heads) is 72-75 cc's but Pontiac heads even from the factory are known to have varied some from published figures, plus we don't know if your heads have been cut. 
Volume in the piston valve reliefs - with the ones you have from the photos, probably 6 cc's

First, Pontiac's published compression ratio numbers are always over-stated. They did that so that racers could 'blueprint' their engines to the published specs and still be NHRA legal.

If I use my assumptions and calculate your actual static compression ratio, it works out to about 9.8:1. Still more than I personally would be comfortable with using iron heads, but it's not all THAT bad plus you did say that you were able to run the stock dizz without getting any pinging. 

Let me ask a really dumb question: Other than the fact you've already spent the money on it, is there some reason you're in love with that new MSD R2R distributor? As long as you weren't getting any misfire problems from the stock unit, that new one isn't going to make any more power than it did. 

I watched an episode of "Engine Masters" on the Motortrend channel recently where they did back to back testing on various different ignition systems. They were running on a pretty "built" Ford 460 test engine that was capable of over 600 on both torque and HPabove 6000 rpm, and tried everything from a stock points unit with worn out points and worn out/pulled off an engine in the back yard set of wires. The engine was quite capable of running to 6000+ rpm, and yes - at around 5000 where the "old" parts started having serious misfire problems it was no contest. HOWEVER - until they got into misfire, the difference in HP/Torque across all the systems (between 2500 and 4500 rpm) was miniscule. The guys on the show were quick to sing the praises and talk about how much 'better' the electronic systems were (of course the show has sponsors) but if you were paying attention to the raw numbers and charts, they told a different story. 

In your situation, since you've already said the stock dizz didn't cause pinging, I'd be very tempted to put it back into the car at least long enough to try to measure what that one's doing both in terms of total mechanical advance and how quickly it comes in, then I'd try to set up the "new one" to behave the same way.

Bear

P.S. On that same episode there was something that happened that I found very funny and curious. At one point they said they were going to test different spark plugs. They never mentioned a brand but I'm betting they were talking about E3's. However, when they came back from "break" after that conversation, somehow they never mentioned spark plugs again and instead showed some completely different testing. My suspicion is, that they tried the plugs and found out they performed no better (and perhaps not as good as) the stock style single electrode plugs so they just kinda swept all that under the rug.


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## ragtopgoat (Sep 26, 2019)

BearGFR said:


> Alrighty - that's information to work with - I still have to make some assumptions on some dimensions, namely:
> Head gasket bore size and compressed thickness - Nominal dimensions are .042-.045 compressed and these days commonly have a bore size of 4.300
> Piston deck clearance (Pontiacs are "usually" around 0.015 "down" unless the block has been zero decked)
> Head chamber volume - "nominal" for those heads (year model 1970 so they're open chamber heads) is 72-75 cc's but Pontiac heads even from the factory are known to have varied some from published figures, plus we don't know if your heads have been cut.
> ...


I decided to go with the R2R dizzy due to more reliability over points, not having to deal with degrading points and changing them (I'm sure many here would argue with me on this topic!). This car mostly looks original, but is not a numbers matched collector. It's a driver and getting better reliability is important to me. Now that I have the MSD installed, immediately the starting and idling were much more stable. With the stock dizzy, I could hear some random misfires at idle, with the MSD, it idles much smoother. 

As for giving up with fixing the pinging with the MSD and going back to the stock dizzy; I don't think it's the fault of the MSD, but purely getting the tune corrected so that it doesn't ping (retard timing, add some octane boost). There's a good reason to switch back and confirming what the advance curve looked like and confirming that something else isn't causing the pinging (maybe it will ping now with the original dizzy). A few months ago, I did check with my dial-back timing light with the original setup and from what I could tell it looked like it was at 36 degrees total, but that I'm not totally convinced of that number, since my timing light at close to 4000 RPM was hard to read, as the lit-up timing mark seemed to dance around at that RPM. 

After doing some searches on Octane Supreme, it appears to be a good option for boosting my octane from 91 to 94 or so. By carrying a couple of cans of the stuff in my trunk, will allow me to make road trips where no race gas is available. So I see light at the end of this tunnel.


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## 67ventwindow (Mar 3, 2020)

This may be a dumb question. Does your timing light dance around like that with your MSD? Just a thought your old distributor being worn may have disguised or prevented the pinging. I don't know how many times I replaced parts with new only for them reveal problems else where. I don't know if you can truly compare the two distributors when you said the old one was missing and idling poor.


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## ragtopgoat (Sep 26, 2019)

67ventwindow said:


> This may be a dumb question. Does your timing light dance around like that with your MSD? Just a thought your old distributor being worn may have disguised or prevented the pinging. I don't know how many times I replaced parts with new only for them reveal problems else where. I don't know if you can truly compare the two distributors when you said the old one was missing and idling poor.


I'm embarrassed to say, but when I set the timing with the MSD, I used the light to check initial timing, as well as checked the vacuum advance timing at idle. But I was assuming that the total timing documented in the manual was accurate so I didn't check my total timing with the timing light. Now that I have a plan to make adjustments and test, I will measure timing for initial and total using my timing light. You make a good point though, that if I get a cleaner reading at high RPM, it could be an indication that the points distributor that came out may have had enough wear that it was masking the problem.


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## armyadarkness (Dec 7, 2020)

If you like mysteries, you can do it like I did. Replace everything at once and then spend 4 months trying to figure out what the Hell happened. I'm hoping it was Colonel Mustard, in the study, with a pipe, but I suspect that it was Jackass, in the garage, with a wrench.


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## tomwadsworth (Sep 30, 2018)

Pontiac Jim might be onto it. I run a tripower on a 468 and had a problem with pinging at WOT. I worked on the timing and curve for weeks. Every possible spring, limiters, ect. I called my builder and he said that the secondary carburetors might be to lean. I went up 4 jet sizes and it improved, a few more and the pinging was gone. Cheap and easy fix.


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## lust4speed (Jul 5, 2019)

Next step should definitely be to test total timing with your dial-back light. I've seen several MSD Ready To Run distributors toss in an extra 6 degrees electronically between 2,200 and 2,400 RPM. I picked it up first on the distributor machine and verified it with both an Equus and a Jacobs dial-back lights with the distributor installed on an engine. Sent MSD a video of the jump and they ignored the video and said I was seeing things. It was definitely an electronic glitch since we could remove springs and have weights go to full advance at idle and still saw the bump as RPM swept through the low 2,000 range.


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## Lemans guy (Oct 14, 2014)

Smart analysis lust4speed...

That is why we love racers,..(I.am not one)...but they test everything and Re verify everything...

..lot’s of guys tell me their cars are running “great” they just want to curve their dist. When we put it on the Distributor machine you wonder how the car even drives....

you see how we can get used to anything and think it is good!

some distributors have so much advance the car is just constantly working against itself.

You are on it now, verify with the timing light. Those bushings may or may not be exact to the chart, the same with the springs. You need a dist machine or I timing light. I like both!

After you get that a fuel curve getting the AFR is also a great step. But that is for another discussion


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## 67ventwindow (Mar 3, 2020)

Lemans guy said:


> Smart analysis lust4speed...
> 
> That is why we love racers,..(I.am not one)...but they test everything and Re verify everything...
> 
> ...


You mention a distributor machine. Is there one out there for a descent price? I seen one where a corvette guy made his own when rebuilding his SUN distributor machine proved to be too pricey.









Corvette Restorer Spring 2019 Page 24






www.ourdigitalmags.com


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## Lemans guy (Oct 14, 2014)

One that works is about $3000 or more, lots out there don’t work and will cost you a lot. But you can do the same thing with a good dial back timing light....Innova has a good digital one, check Summit about $100 dollars.....


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## ragtopgoat (Sep 26, 2019)

I am thinking about installing timing tape on the harmonic balancer to double check my timing, and I have a (probably stupid) question about installing the timing tape. I understand needing to use tape that is the proper size for the diameter of the HB, but my question is how it is installed. My assumption is that I would orient the zero degree mark on the tape with the TDC mark on the balancer, then the increasing degree marks on the tape would run clockwise from the TDC mark. So if looking at the harmonic balancer from the front of the car, if the TDC mark were at 9 o'clock, 36 degrees on the tape would be at (approximately) 11 o'clock. Then when checking total timing, I would confirm that whatever number on the tape lines up with the zero degree pointer on the timing cover. Do I have that right?


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## PontiacJim (Dec 29, 2012)

Lemans guy said:


> One that works is about $3000 or more, lots out there don’t work and will cost you a lot. But you can do the same thing with a good dial back timing light....Innova has a good digital one, check Summit about $100 dollars.....


Or check your local paper for estate sales, especially those having auto shops.

Got it for $400 with an old Grant "Flamethrower" style distributor for a Chevy stashed inside. It is an older machine, early 1960's. Have not messed with it, or even plugged it in yet. But if it doesn't work, still cool man cave item. Just another thing to add to my "to-do" list of items to tinker with.


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## PontiacJim (Dec 29, 2012)

ragtopgoat said:


> I am thinking about installing timing tape on the harmonic balancer to double check my timing, and I have a (probably stupid) question about installing the timing tape. I understand needing to use tape that is the proper size for the diameter of the HB, but my question is how it is installed. My assumption is that I would orient the zero degree mark on the tape with the TDC mark on the balancer, then the increasing degree marks on the tape would run clockwise from the TDC mark. So if looking at the harmonic balancer from the front of the car, if the TDC mark were at 9 o'clock, 36 degrees on the tape would be at (approximately) 11 o'clock. Then when checking total timing, I would confirm that whatever number on the tape lines up with the zero degree pointer on the timing cover. Do I have that right?


How do you know the balancer is correct? Maybe timing gear wear, chain stretch, or balancer outer ring has slipped.


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## ragtopgoat (Sep 26, 2019)

PontiacJim said:


> How do you know the balancer is correct? Maybe timing gear wear, chain stretch, or balancer outer ring has slipped.


I have not confirmed the TDC mark myself. I'm mostly assuming that it is correct based on the fact that initial and total timing was set with the points distributor and was running pretty well without pinging. 

If I do test TDC with a piston stop, do I need to remove the rocker arms on cylinder #1 to prevent the valves from hitting the stop?


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## PontiacJim (Dec 29, 2012)

ragtopgoat said:


> I have not confirmed the TDC mark myself. I'm mostly assuming that it is correct based on the fact that initial and total timing was set with the points distributor and was running pretty well without pinging.
> 
> If I do test TDC with a piston stop, do I need to remove the rocker arms on cylinder #1 to prevent the valves from hitting the stop?


Aaha! Curve ball.  You will want to make sure that the piston is at top dead center. You can't rely on the closed positioning of the valves, but they can confirm the compression stoke.

You will want to get a tool that gets inserted into the spark plug hole that will confirm the piston is at TDC. I believe you can make a tool as well. I think finding TDC has been covered here before. But I would do this to confirm TDC and then position your timing tape accordingly. It will also let you know if the balancer is incorrect or has moved/slipped, and you can check the play in the timing gears/chain because excess slop will affect timing as I am sure you know.

I have never used a TDC tool, so I cannot recommend anything. Hopefully another member will chime in or you can check YouTube as they most likely cover this as a how-to video.


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## ragtopgoat (Sep 26, 2019)

PontiacJim said:


> Aaha! Curve ball.  You will want to make sure that the piston is at top dead center. You can't rely on the closed positioning of the valves, but they can confirm the compression stoke.
> 
> You will want to get a tool that gets inserted into the spark plug hole that will confirm the piston is at TDC. I believe you can make a tool as well. I think finding TDC has been covered here before. But I would do this to confirm TDC and then position your timing tape accordingly. It will also let you know if the balancer is incorrect or has moved/slipped, and you can check the play in the timing gears/chain because excess slop will affect timing as I am sure you know.
> 
> I have never used a TDC tool, so I cannot recommend anything. Hopefully another member will chime in or you can check YouTube as they most likely cover this as a how-to video.


I just replaced my fuel pump and while I had it out, I poked my finger in against the timing chain, to see if it had any slack. It seemed to be very tight. Not sure if that's a legit test of it, as I could not see much of it and was not sure if I was pushing on it was between the gears.


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## gtojoe68 (Jan 4, 2019)

Blend it with the 100 octane. Or find an airport that’ll sell you some AV fuel you can mix with the pump. That’s what I do. I also run 10:1 comp and all the timing changes I’ve tried have no effect when WOT. Also 4 speed car but 3.90 gears.
I will say, I’m curious what PJ would say to your conundrum but with mechanical advance MSD dizzy that I have


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## Lemans guy (Oct 14, 2014)

Did you dial the timing way back to say 30 total and see if it still pings at WOT?...


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## PontiacJim (Dec 29, 2012)

gtojoe68 said:


> Blend it with the 100 octane. Or find an airport that’ll sell you some AV fuel you can mix with the pump. That’s what I do. I also run 10:1 comp and all the timing changes I’ve tried have no effect when WOT. Also 4 speed car but 3.90 gears.
> I will say, I’m curious what PJ would say to your conundrum but with mechanical advance MSD dizzy that I have


I posted my thoughts on page 1, post #16. Compression at that number with iron heads basically will need more octane. You will read where others say they can run that compression with pump gas, but then I have to question as to whether or not they are at sea level or at a high altitude where more compression is needed because the air is less dense at the higher altitudes. Some say to use a wide LSA to bleed off some of the cylinder pressure at the lower RPM's and you will pick up the "soggy" bottom end power/torque at the higher RPM's - not what you really want for the street and it also means an engine that has to spin much higher RPM's to work well.

Dropping timing back too much will be giving up power and retarding timing can cause the engine to run hot and then you now have other problems to contend with.


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## Lemans guy (Oct 14, 2014)

Agree, not saying one should leave it at 30, just as a test to see if pinging is reduced or eliminated, then dial back up in two degree implements to see where it is......

Also maybe your compression is even higher than you think. You will need that combination of octane, perfect timing and good cooling system to get there.


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## ragtopgoat (Sep 26, 2019)

Over the weekend, I changed the MSD to use the 21 degree limit bushing and the stiffer springs (heavy silver and light silver springs). So now the total timing will be all in at 3400 RPM. I set base to 10 degrees. Testing with both a timing light and timing tape on the harmonic balancer, I show 10 degrees initial, 32 degrees total. Road testing with 91 octane, I had no pinging with this setup. The throttle was very responsive, no hesitation or stumbles. I ran it up to 5000 RPM at WOT in multiple gears and on a steep hill and I could not hear any pinging. I also checked timing at idle with the vacuum advance connected, which showed 25 degrees at idle. So it appears that the vacuum advance adds 15 degrees, vs 10 degrees that the MSD manual indicated. That actually is better for idle and part throttle timing.

I should also note, a year ago I had this car in to Performance Fabrication (in San Carlos, CA), to help with a blown head gasket due to the previous mechanic not properly torquing down the head bolts. After they reinstalled the heads with new gaskets, they checked my timing with the original dizzy and documented it in the invoice. It was set to 12 initial, 31 total. So given that it didn't ping before the MSD upgrade, that gave me a good indication of what I should target for initial/total.

So with all the help I received here, I was able to achieve the goal to get a good tune without pinging. As an added measure of safety, I am going to mix in some 100 octane race gas, targeting 94 - 95 octane. I'm also going to try Octane Supreme, which has gotten good reviews for increasing octane by adding Tetraethyllead. I can carry this with me on any road trips where I might need to refuel when no race gas is available.


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## armyadarkness (Dec 7, 2020)

ragtopgoat said:


> Over the weekend, I changed the MSD to use the 21 degree limit bushing and the stiffer springs (heavy silver and light silver springs). So now the total timing will be all in at 3400 RPM. I set base to 10 degrees. Testing with both a timing light and timing tape on the harmonic balancer, I show 10 degrees initial, 32 degrees total. Road testing with 91 octane, I had no pinging with this setup. The throttle was very responsive, no hesitation or stumbles. I ran it up to 5000 RPM at WOT in multiple gears and on a steep hill and I could not hear any pinging. I also checked timing at idle with the vacuum advance connected, which showed 25 degrees at idle. So it appears that the vacuum advance adds 15 degrees, vs 10 degrees that the MSD manual indicated. That actually is better for idle and part throttle timing.
> 
> I should also note, a year ago I had this car in to Performance Fabrication (in San Carlos, CA), to help with a blown head gasket due to the previous mechanic not properly torquing down the head bolts. After they reinstalled the heads with new gaskets, they checked my timing with the original dizzy and documented it in the invoice. It was set to 12 initial, 31 total. So given that it didn't ping before the MSD upgrade, that gave me a good indication of what I should target for initial/total.
> 
> So with all the help I received here, I was able to achieve the goal to get a good tune without pinging. As an added measure of safety, I am going to mix in some 100 octane race gas, targeting 94 - 95 octane. I'm also going to try Octane Supreme, which has gotten good reviews for increasing octane by adding Tetraethyllead. I can carry this with me on any road trips where I might need to refuel when no race gas is available.


That's great news. FYI, I've never seen an MSD, which didn't use an adjustable vac can. So if it's running good, then great, but you should also have some adjust ability on the can.


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## ragtopgoat (Sep 26, 2019)

armyadarkness said:


> That's great news. FYI, I've never seen an MSD, which didn't use an adjustable vac can. So if it's running good, then great, but you should also have some adjust ability on the can.


I'll have to check on whether the VA is adjustable. I looked in the manual and other than having a piece to lock out the VA and remove the can, I could not see anyway to adjust it.


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## armyadarkness (Dec 7, 2020)

ragtopgoat said:


> I'll have to check on whether the VA is adjustable. I looked in the manual and other than having a piece to lock out the VA and remove the can, I could not see anyway to adjust it.


I just bought a few myself and they were all adjustable. But, you never know. The whole idea behind the MSD is the complete ability to customize all aspects of timing, so I'd be surprised.


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## armyadarkness (Dec 7, 2020)

Well, they have stopped using the adustable can, so you're right. However, it does look like the can you got give 15 degrees at 12 inches of vacuum. So yes, assuming that you have 12 inches of vac...


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## PontiacJim (Dec 29, 2012)

ragtopgoat said:


> Over the weekend, I changed the MSD to use the 21 degree limit bushing and the stiffer springs (heavy silver and light silver springs). So now the total timing will be all in at 3400 RPM. I set base to 10 degrees. Testing with both a timing light and timing tape on the harmonic balancer, I show 10 degrees initial, 32 degrees total. Road testing with 91 octane, I had no pinging with this setup. The throttle was very responsive, no hesitation or stumbles. I ran it up to 5000 RPM at WOT in multiple gears and on a steep hill and I could not hear any pinging. I also checked timing at idle with the vacuum advance connected, which showed 25 degrees at idle. So it appears that the vacuum advance adds 15 degrees, vs 10 degrees that the MSD manual indicated. That actually is better for idle and part throttle timing.
> 
> I should also note, a year ago I had this car in to Performance Fabrication (in San Carlos, CA), to help with a blown head gasket due to the previous mechanic not properly torquing down the head bolts. After they reinstalled the heads with new gaskets, they checked my timing with the original dizzy and documented it in the invoice. It was set to 12 initial, 31 total. So given that it didn't ping before the MSD upgrade, that gave me a good indication of what I should target for initial/total.
> 
> So with all the help I received here, I was able to achieve the goal to get a good tune without pinging. As an added measure of safety, I am going to mix in some 100 octane race gas, targeting 94 - 95 octane. I'm also going to try Octane Supreme, which has gotten good reviews for increasing octane by adding Tetraethyllead. I can carry this with me on any road trips where I might need to refuel when no race gas is available.


Well, I am impressed. Stock "093" heads and .040" head gaskets which should be near 10.0 compression. I am going to add your timing numbers/curve to my timing file. Would have bet money it would not ping on any less than 94-95 octane at that compression.

Good going.


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## Lemans guy (Oct 14, 2014)

Good work!...


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