# Rocker Arm Noise - '65 GTO



## Roqetman (Aug 31, 2015)

This may sound crazy but I'm getting excessive rocker arm noise with the valve covers on, when they're off there is no noise. Today I adjusted the valves and with the valve covers off there was no unusual or excessive noise. It's as if the valve covers are amplifying the normal sound of the valve train. It's a 389 with '69 400 cast iron heads and stamped steel rocker arms. I bought reproduction chrome valve covers for a '65 389, they do not have baffles. Would valve covers with baffles be quieter? Could the stock rockers be contacting the valve covers? Does anyone where I can buy valve covers with baffles? I've already searched several web site. I'd like to know if anyone else has had this problem and how is was resolved. Thanks!


----------



## PontiacJim (Dec 29, 2012)

Sounds odd. It may be as you mentioned, the rockers could be hitting the tops of the covers. If you put your hand on top of them do you feel any movement? Maybe something as simple as a double valve cover gasket may do the trick IF you need to raise the covers a tad bit. Aftermarket does not always mean factory correct and they may be an incorrect/too short of height.

Just a guess.


----------



## BearGFR (Aug 25, 2008)

Pull the covers off and examine both the insides of the covers, and all the "movey" parts in the heads very carefully, looking for any 'shiny spots' that don't seem to belong there. Those will be a telltale of something that's making contact.

Bear


----------



## Roqetman (Aug 31, 2015)

I did feel some movement when I put my hands on the valve covers. If a second gasket is enough to clear the valve train, I would think it should it be glued to the first gasket, correct? I will also inspect the inside of the v covers for contact marks. Thanks!


----------



## extinctmake (Feb 8, 2011)

I think the valve covers for old 389s were different from the covers of the 1967 and later Pontiac V8s. The old 389s had that hump on the opposite ends of the valve cover. Maybe that doesn't make any difference, but the valve covers on a 400 look different from those off a 389.

Do you still have the valve covers to the 400 heads you have on your 389? You could put them back on and see if the noise goes away or changes.

I know a lot of those reproduction parts fit like O.J.'s glove, so it won't be a surprise if your problem stems from a bad fit of the reproduction valve covers.


----------



## BearGFR (Aug 25, 2008)

Roqetman said:


> I did feel some movement when I put my hands on the valve covers. If a second gasket is enough to clear the valve train, I would think it should it be glued to the first gasket, correct? I will also inspect the inside of the v covers for contact marks. Thanks!


Examine your rocker arms and valve retainers for shiny spots as well...

Also, previously you mentioned that you had 'adjusted the valves'. Is your valve train stock? As in factory Pontiac rockers, studs, balls, and nuts? If so, they aren't adjustable... The factory system is designed such that you torque the nuts down onto the 'bottleneck' on the stud. I forget what the exact torque spec is...

Bear


----------



## Roqetman (Aug 31, 2015)

They appear to be stock stamped steel rocker arms with screw in studs and push rod retainers. We adjusted the rockers with the engine warm and at idle, we backed off the nut until the rocker started clicking, then tightened the nut down 1/2 turn. If that is not the correct procedure, then I need to find the torque spec and proper procedure. The engine block is the original numbers matching 389, the heads are cast iron from a 69 400. The number cast on the center exhaust ports appears to be 48 but the 8 is hard to distinguish on both heads. 

When I bought the car in Aug 15 it had chrome Edelbrock V covers and they are fairly tall. The after market valve covers I ordered for a '65 389, were a lower profile and at the time didn't realize the heads had been changed. They gave it the stock appearance I wanted. But now I'm going back to the Edelbrock to see if the noise goes away... I bet it will. Thanks for your input!


----------



## BearGFR (Aug 25, 2008)

If you have all factory style parts:










Even if you have different rocker arms --- what matters is the stud, ball, and nut... These are not adjustable, regardless of whether the studs are pressed in or screwed in. The nut is designed to seat onto the bottleneck shoulder on the stud. Torque to 20 lb.ft. Done. If they're not seated like this, they WILL back off and you'll get noise. 
However, it doesn't take much modification (head milling, etc) to throw everything out of whack. So in order to make the valve train adjustable one MUST use some sort of locking nut (poly lock) such as something like these:










...that have a jam screw in the center that, when tightened down against the top of the stud, will hold them in position.

Bear


----------



## Roqetman (Aug 31, 2015)

BearGFR, I have the factory style rockers shown in the first picture with hydraulic lifters and screw in studs. Can you tell me the procedure to tighten to 20 lbs or advise me of a link for instructions? Thanks!


----------



## Roqetman (Aug 31, 2015)

See pic below.


----------



## PontiacJim (Dec 29, 2012)

Roqetman said:


> BearGFR, I have the factory style rockers shown in the first picture with hydraulic lifters and screw in studs. Can you tell me the procedure to tighten to 20 lbs or advise me of a link for instructions? Thanks!


Note in the photo Bear provided that the screw-in rocker arm stud has a shoulder. The stud goes from a 7/16" base and then necks down to a 3/8" threaded end, thus the term "bottle neck" stud. The stronger aftermarket screw-in studs have the 7/16" base and a 7/16" threaded end providing a much stronger stud. This is one of the recommended upgrades if you are going with a better than stock cam having higher lift & heavier valve springs, faster opening rate, going to 1.65 ratio rocker arms, or using a roller cam. 

With your factory set-up, you simply torque them down with a torque wrench set at 20 foot lbs. It is best to have the rocker arms on the base of the cam where there is no pressure - lifting the rocker arm up. Simply rotate the crank until the rocker arms are even/same position with no lift. Then torque.

The factory rocker arm nuts are not of the locking type and even when I have used the aftermarket supplied factory type rocker arm nut lock nuts which say they will lock down and not back off - they do after time. 

The photo Bear supplied shows the rocker arm pivot ball which seats in the rocker arm. It appears to be a non-grooved smooth ball as opposed to a grooved pivot ball. I uploaded a photo that shows a grooved rocker arm ball. You can see the small grooves on the sides - the balls are not smooth. These type of Rocker Arm Pivot Balls are specially "grooved" on the lower radius to improve lubrication while reducing friction and heat with stock style, stamped steel rocker arms when employing higher spring pressures in high performance applications. In some instances, rocker arm galling/blueing can occur along with excessive high heat due to the lack of lubrication under high spring loads or high RPM's and can wear out/damage the rocker arms and cause a change in rocker arm geometry due to the worn surfaces in the rocker arm cup. Most aftermarket rocker arms typically come with the grooved balls or you can buy them as a set. 

Here is what Comp Cams says about their rocker arms and use of 3/8" self-locking rocker arm nuts - Pontiac Magnum Roller Rocker Arms™ are supplied with _larger, thicker rocker arm balls _and 3/8" self-locking nuts. These components convert your non-adjustable valve train to permit valve lash adjustment (by using thicker rocker arm balls which don't allow the rocker nut to be torqued down on the bottle neck studs like the factory rocker nuts need to do). DO NOT TORQUE ADJUSTING NUTS PER FACTORY SPECIFICATIONS. Follow steps 7, 8, & 9  for the correct valve adjustment procedure. Personally, *Ditch the 3/8" self-locking nuts described above and get the Polylocks.* Then adjust your valves using the "clicking" method.

Use of high pressure or high volume oil pumps can cause galling of the pushrod and pushrod seat, and burn up the pivot ball and the rocker. If high volume or high pressure oil pumps have to be used, then you will need to purchase a set of valve train oil deflectors to put over the rockers arms, ensuring that the oil does not shoot over the top of the rockers. Pontiac used the oil drippers which bolted to the heads or the valve covers which had oil drippers spot welded to them. This catches/keeps the oil "dripping" down into the rocker arms to keep them and the rocker arm balls lubricated.

That said, _you cannot adjust your valves using the valve "clicking" sound_ and then tighten until it stops. If you want to go that route, you have to use the Polylocks as shown at the bottom of the photo. These come in 3/8" and 7/16" versions as well as tall and short installed heights depending on your needs and valve cover clearances. Some will be too tall to use with stock valve covers and require aftermarket covers being taller.


----------



## Roqetman (Aug 31, 2015)

PontiacJim, thanks for the info. I will double check for the grooved rocker ball. As I recall my rocker balls had an oblong opening but I did not notice any grooves. We first tried the cold method shown Below but when we got to #8 intake it was out of whack. We then started the engine and let in warm up and did the clicking method and everything appeared to be good. When I put he Valve covers back on we could hear racket that seem to be coming from the valve covers. Again thanks for all the info, this was modified before I bought and it's been a year and a half since I've had it on road. It has a mid-range power cam, headers, Edelbrock intake and 750 Q-Jet. I will update you in the next couple days with what I find.

Pontiac Rocker Arm Adjustment

Whether you have decided to stay with the stock type stamped rocker arms or Competition Cams Magnum Rollers Rockers as pictured here, or something far more exotic, you will need to adjust valve lash. Torquing the adjusting nut per the old Chilton's to 20-25 ft pounds won't work on any heads that have been milled. This is especially true with the high lift cams of today. The valve train needs to be adjustable. Some form of lock nut must be used. I prefer Mr. Gasket's poly lock nuts.

In the past, I've adjusted hydraulic lifters with the engine running, backing off the nut until the rocker clattered, and then turning the nut slowly until the noise dissipated. That process sure works but is just too messy for me. No matter how hard I tried, oil got past the restrictor clips, and my fabricated valve cover oil catchers--oil went everywhere. Nobody should endure that nonsense. I 've found that adjusting valve lash can really be performed while the engine is cold. The adjustment, when done accurately will preclude further adjustment with the engine running.

An important point to remember in adjusting valve lash is that the adjustment must be performed while the lifter is sitting on the base circle of the cam lobe you will adjust. Below is the technique I use. The sequence works on all V8's with the Pontiac firing order--

Firing Order
The firing order on all Pontiac motors is 1-8-4-3-6-5-7-2. The best place to start the adjustment process is to begin with the #1 cylinder. Whether you are building a new motor, swapping in a cam, or adding other upper valve train components, start with the #1 cylinder. Silly as this may seem to some, the #1 cylinder is on the driver's side cylinder bank. The driver's side has the odd number cylinders: 1-3-5-7. The passenger side has the even numbered cylinders: 2-4-6-8. [Number's 7 and 8 are closest to the firewall. (There will be a test on this later.)]

Identify Intake and Exhaust Valves/ Springs
You can't adjust anything until you know where everything is located. This sounds really basic, but you must accurately identify each valve. If you must, use a small piece of masking tape and stick it on the head with each corresponding valve identified. For example, 1X and 1I. Believe me, doing this will save some time. Preparation makes things go smoothly. Besides, who like to do things over. You won't do the wrong valve doing it this way.

Locate TDC on #1 Cylinder 
Numerous valves will be adjusted at one time in this process. You must locate top dead center (TDC) of #1 cylinder. I prefer turning the crank by hand because I know exactly where TDC is on my motor. Remove all the plugs if you haven't already done so; it makes life easier on you or your starter. Locate TDC on #1 by locating the '0' on the timing tab with the harmonic balancer line. You can determine whether it's really the #1 cylinder a couple of ways. One way is too look at the hydraulic lifters. If the hydraulic lifters are down and level you're on # 1 TDC. Another way is the old "thumb in the dike" method. Place your thumb in the number one spark plug hole while the engine is being turned by the starter. When TDC is near, your finger will be pushed out by the compression. ( I know this is basic stuff.) When that happens, align the harmonic balancer that fraction or so to get TDC. Remember, the lifters must be on the base circle of the cam lobe for the adjustment to work.

Adjustment Begins
With the engine at TDC on #1 cylinder you can properly adjust the following valves after lubricating the rocker ball, valve stem, and pushrod contact point:

INTAKE 1 2 5 7
EXHAUST 1 3 4 8
The Adjustment Procedure
Remove all of the slack out of the pushrod and rocker arm by slowly tightening the adjusting nut. You must use your sense of touch here. Lightly turn the rod with your fingers while tightening the nut. As you do so, you will begin to feel resistance. When the resistance reaches a point where it requires more grip (torque) to turn the rod, stop! At this point you have removed all of the play out of the pushrod and are at "zero lash." Now you may make the final adjustment. With wrench or socket in hand, tighten the nut 180 degrees (a 1/2 turn). If you are using poly lock nuts, tighten the set screw against the rocker arm stud after the 1/2 turn. Be sure the adjusting nut does not move. (Hold it stationary with a wrench while you use the allen wrench to tighten the set screw.) Thereafter, for added insurance, add a tad more turn to the poly lock nut...just a tad. This will set the screw tightly against the stud so it won't back off.

Do all intakes valves (1-2-5-7) first and then proceed with the exhaust valves (1-3-4-8). Since you are using "feel" take your time. Run through each valve twice, if you must, before proceeding to the next group of valves.

Locate TDC on #6 Cylinder
The next step is to rotate the engine 360 crank degrees to get the #6 piston at TDC. Use the same technique for locating TDC on #1 .

Adjustment Resumes 
With the engine at TDC on #6 cylinder you can adjust the following valves after lubricating the rocker ball, valve stem, and pushrod contact point:

INTAKE 3 4 6 8
EXHAUST 2 5 6 7
Adjustment Procedure Reiterated
Remove all of the slack out of the pushrod and rocker arms by slowly tightening the adjusting nut. You must use your sense of touch here. Lightly turn the rod with your fingers while tightening the nut. As you do so, you will begin to feel resistance. When the resistance makes it difficult for you to turn the rod without more grip (torque), stop! At this point you have removed all of the play out of the pushrod. You're now at "zero lash." Now make the final adjustment. With wrench or socket in hand, tighten the nut 180 degrees (a 1/2 turn). If you are using poly lock nuts, tighten the set screw against the rocker arm stud. Be sure the adjusting nut does not move. Hold it stationary with a wrench while you use the allen wrench to tighten the set screw.

Do intake valves (3-4-6-8) first then proceed with the exhaust valves (2-5-6-7). Since you are using "feel" take your time. Run through each valve twice to be certain everything looks and "feels" right to you.

Final Step
Re-lubricate the rocker assembly before installing the valve covers. If you've taken your time to be accurate no further adjustment is necessary.


----------



## BearGFR (Aug 25, 2008)

The process for the factory setup is... there is no process. Remember they aren't adjustable - all the rocker nuts get tightened down onto the stud 'bottlenecks', tight enough so that they won't come loose. So I guess the process is 1) get a torque wrench 2) tighten all the nuts to 20 lb. ft. 

All the 'processes' that have you turning the engine over to different positions, doing certain valves on certain cylinders --- don't apply here. What those procedures do is ensure that the lifter being adjusted is at its lowest point, riding on the base circle of the cam, so you can take all the slack out of the pushrod at that point. None of that matters with the factory Pontiac setup - it's not adjustable - all you're doing is getting the nuts tight enough so they won't back off. The lifter/pushrod preload will be whatever it will be at that point. If you think about it, you'll see all that matters is while the engine is running that the piston inside the lifter that is actually operating the pushrod never bottoms out in the lifter bore nor does it ever hit the retaining clip at the top of the lifter bore. As long as it's riding "somewhere in the middle" at all rpm, then everything's going to be hunky-dory.

Pontiacs are -NOT- chevys...

The only times any of those processes apply are in situations where the system has been converted to one that IS adjustable - using some sort of poly-lock rocker nut.

Bear


----------



## PontiacJim (Dec 29, 2012)

OK, I see where you got your info. Bear is correct, and as I stated earlier, the factory Pontiac heads with the bottleneck studs* are not intended to be adjustable using the factory rocker arm nuts*. They are not locking nuts and need to be torqued down to prevent them from backing off. The Pontiac article is a little misleading/confusing when they state in the opening sentence,"_Whether you have decided to stay with the stock type stamped rocker arms or Competition Cams Magnum Rollers Rockers as pictured here, or something far more exotic, you will need to adjust valve lash._"

What they should have said first was, "_Torquing the adjusting nut per the old Chilton's to 20-25 ft pounds won't work on any heads that have been milled._ (EXCEPT, they did not state how much has to be milled, .020", .030", .060"???. I've had heads milled .010" to clean up the surfaces - no need to use adjust anything, just torque the rocker arm nuts per factory). _The valve train needs to be adjustable. Some form of lock nut must be used. I prefer Mr. Gasket's poly lock nuts._" As noted earlier, the Comp Cams Magnum Rollers explain their process and include thicker rocker arm balls along with factory type locking rocker arm nuts.

Again, you can certainly use the "clicking" method to adjust your valves *AS LONG AS* you use the correct and needed _locking rocker arm nuts or Polylocks_ to do this. Otherwise, you cannot do this with your factory rocker arm nuts as they will back off IF not torqued down to 20-25 ft lbs of torque.

So if you want to be on the safe side because you are not sure about the clearances because you don't know how much the heads, if any, have been milled, then adjusting your valves by the "clicking" method is fine, but do get a set of Polylocks (or factory style locking rocker arm nuts - https://www.summitracing.com/parts/cca-1400n-16/overview/ ) so that you can do this. The Comp Cams locking nuts are cheap and will work, but I and other prefer the Polylocks which are a little more work to use, but typically hold better in my experience, than the locking nuts. However, you will not have to worry about valve cover clearance issues as you might with the Polylocks. So you might just want to order the Comp Cams locking rocker arm nuts and the grooved balls (if you don't have them already), then you will be good to go. :thumbsup:


----------



## Roqetman (Aug 31, 2015)

Ok, so if I have bottle necks studs, I simply torque the nuts to 20-25 lbs, no worries about rotating the engine to be on the base of the cam, Correct? I will double check to make certain I have bottle neck studs. 

BTW, The article I copied was from Pontiac Street Performance by [email protected]. Thanks guys for you time and expertise, this is much simpler than I thought. The last vehicle I adjusted valves on was a '65 VW Beetle back in the day, and I hired a mechanic to do that! LOL!


----------



## Roqetman (Aug 31, 2015)

Well guys, I took the valve covers off again and it was very apparent the rocker arms were beating the shit out of the valve covers, pardon my French! The #8 exhaust rocker had hammered a hole through the V cover! All the other rockers, except one where the breather is, showed marks on the V covers. Now I know why the previous owner had high rise Edelbrock V covers! These are '69 400 #48 heads. I bought the original style valve covers for a '65 389. I do have the bottle neck studs 7/16 & 3/8" and ... the rocker ball has an oblong hole. With this set up I suppose torquing to 20-25 lbs is still the correct way to tighten the rockers? I will probably add poly locks in the near future. Thanks for all the advice!


----------



## PontiacJim (Dec 29, 2012)

RM: "I bought the original style valve covers for a '65 389."

PJ: You can get valve cover spacers in a variety of heights, 3/8", 1/2", or 1" that will fit under your 389 valve covers to get them higher to clear the rockers if you still want to go with the 389 valve covers. They come in polished or natural finishes. If I used them, I might get a natural finish and paint them the same color as the block to make them blend in a little better. Here is one company that offers them, they are high priced, but there are others and prices do vary. MediceMfg ...Valve Cover Spacers - Pontiac

If you do not need much additional clearance, then the cheaper alternative would be to double up on the valve cover gaskets. Butler has thick gaskets in 5/16". Glue 2 together with some good old fashion Indian Shellac and that will give you 5/8", and tighten them down snug will probably bring it more in like 1/2". http://butlerperformance.com/c-1234816-gaskets-valve-cover-gaskets.html

RM: " I do have the bottle neck studs 7/16 & 3/8" "

PJ: Then you torque them down and let it go at that. BUT, keep reading under "My Concern.".

RM: "the rocker ball has an oblong hole."

PJ: Oblong hole? Is this where the stud goes through, or are you describing the oblong "hole" on the side of the ball - which is the oil groove? The hole in the center of the ball that fits down onto the rocker stud should be round, not oblong, if that is what you are describing. If the center hole is oblong, this may allow the rocker arm to shift around. Your rocker arm should have a nice long slotted hole so it does not go into bind. You typically want these when cam lift nears .450" and higher. I provided a photo from the net. The rocker on the left is a typical rocker arm. The rocker arm on the right is an aftermarket "long slot" rocker arm.

PJ: *NOTE: MY CONCERN.* Do you know if the heads have been milled or how much, if any? If the heads have been milled as I stated earlier, simply torquing the rocker arm nuts down to factory 20-25 ft lbs may not be a good thing. Milling heads, using thinner head gaskets, or even valve jobs can all alter the rocker arm geometry. Hydraulic lifters require a "preload" of .020" - .060". When the parts were factory new or if the heads were never milled, no need to worry about this. But if the heads were milled and great amount and you torque the nuts down, you may cause the plunger in the hydraulic lifter to seat too low in the body and this can lead to problems - to include holding the valves slightly open.

Fairly simple to check this. Since you will be torquing the nuts down, a different method needs to be used in making sure you have the correct preload on the lifters and you don't bottom them out IF any changes were made to the heads. You Tube has a couple of videos on setting lifter preload on non-adjustable valve trains that may be of help, and you can use a dial indicator for greater accuracy as well.

I would only check one set of rocker arms to make sure, the rest _should_ be OK. These instructions are from Crane Cams. 

*Adjusting Hydraulic Lifters for Proper Preload* 

In order to adjust the preload the lifter must be properly located on the base circle or “Heel” of the lobe. At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

1. Remove the valve covers, and pick a cylinder you are going to set the preload on.
2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod (and you cannot move the pushrod up & down), you are at “Zero Lash”. Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster (this is in reference to Polylocks) into position. The intake is now adjusted properly.
5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.


From what I have read here on the internet, 1 full turn of a 3/8"-24 rocker arm nut will compress the lifter plunger .040". What I would do is get the lifter to "zero lash" by following step #4 above. Then I would use the torque wrench and set it to 20 ft lbs. Tighten the nut making note of how much you have to rotate the nut before it reaches the torque value of 20 ft lbs (torque wrench slips/clicks @ 20 ft lbs). If it torques down to 20 ft lbs anywhere from 1/2 to 1 full turn of the nut, then you are good. IF it takes more than 1 full turn, let's say 1 1/2 or 2 turns, then then your rocker arm geometry is off and you will need to fix this. If you can turn the nut more than 1 full turn before the nut torques down, you will need longer pushrods. If the nut were to tighten down less than 1/2 a turn, then you would need shorter pushrods.

If you find you need a longer or shorter pushrod, then this conversation goes to the next level - checking/verify your rocker arm geometry. Here is a simple way to do this should this be the next step: How to Verify Valvetrain Geometry - Lunati Power 

I assume this is probably a little confusing, even for me, but I don't want to see any engine damage come from a wrong adjustment on the rocker arms not knowing exactly what has been done to the engine's heads. I am no engine building expert, but there are things I know to check when building or playing around with an engine. So take all this with a grain of salt as they say. :thumbsup:


----------



## Roqetman (Aug 31, 2015)

PJ, thanks again for info. Since the 389 valve covers are now ruined, I am going to buy a new set for the '69 400 heads. I will call the previous owner about whether or not the heads were shaved. He had the engine rebuilt in '04 with 10.75:1 compression and it has probably less than 5,000 miles since then. Recent compression check showed a range of 190-210. Last week we used the "clicking" method to take slack out of the rockers, assuming the heads have not been milled should I still torque the rocker nuts to 20-25 lbs or leave as is?

Which brings me to another question. I've read where today's 93 octane gas is not compatible with high compression engines, I've been adding octane booster and it runs fine. But I wonder how much I could lower the compression with thicker head gaskets? Any recommendations on thickness to get to a target compression ratio? Thanks, Roqetman. PS, I did not find the pic of the rocker arms you referenced above.


----------



## PontiacJim (Dec 29, 2012)

Roqetman said:


> PJ, thanks again for info. Since the 389 valve covers are now ruined, I am going to buy a new set for the '69 400 heads. I will call the previous owner about whether or not the heads were shaved. He had the engine rebuilt in '04 with 10.75:1 compression and it has probably less than 5,000 miles since then. Recent compression check showed a range of 190-210. Last week we used the "clicking" method to take slack out of the rockers, assuming the heads have not been milled should I still torque the rocker nuts to 20-25 lbs or leave as is?
> 
> Which brings me to another question. I've read where today's 93 octane gas is not compatible with high compression engines, I've been adding octane booster and it runs fine. But I wonder how much I could lower the compression with thicker head gaskets? Any recommendations on thickness to get to a target compression ratio? Thanks, Roqetman. PS, I did not find the pic of the rocker arms you referenced above.



OK, just added the pic. Left is regular, right is long slot.

You do not use thicker gaskets to lower compression.

Yes, assuming the heads have not been milled, just torque them down and you will be good to go.


----------



## Roqetman (Aug 31, 2015)

Thanks for the pics, I'll compare mine to the ones shown. The previous owner didn't recall if the heads had been milled. Thanks again for all your time and advice. You all have been very helpful! Roqetman


----------



## Roqetman (Aug 31, 2015)

PontiacJim and BearGFR, It's me again. I bought and installed a new set of 400 valve covers and they fit good! This morning I started tightening the rocker arms to 25 ft lbs as advised for stock valve train. Started on the driver side, all went well. Inspected the rocker balls, rocker arms and push rods. Got to #4 Exhaust and things went south... last week we tightened the rockers using the clicking method and number 4 exhaust was cranked down tighter than most. I took it apart and noticed the end of the push rod was barely visible, had to fish it out with needle nose pliers. I inspected the parts and everything looked good. Put the push rod and rocker back on and torqued to 25 ft lbs. The push rod is not even touching the rocker arm, about a 1/2" short. Does this mean I have collapsed lifter or bad cam lobe? See pics of rockers and also #4 exhaust. Thanks, Roqetman.


----------



## Roqetman (Aug 31, 2015)

Never mind.... discovered I missed the lifter on #4 exhaust when I put the push rod back in. Corrected that and Torqued all the rockers to 25 ft lbs and it's purring like a Tiger! Thanks again for all the advice. I learn something new everyday!


----------



## Colorado67GTO (Sep 11, 2014)

I am in the middle of this process as well and have been reading all of these posts in detail. I think I understand all that has been posted and have been following the instructions. Thanks for all the information. 

My question is around the lifter. If I follow the logic of the stock setup with bottleneck studs and no cuts on the heads, you can torque the stud nuts down to the shoulder of the stud. The lifter has enough spring in it to take up any minor difference in height/geometry. Do I have that right?

The reason I ask is that when I start to torque down the nut, as soon as there is any tension on the push rod, I can see the valve opening long before the nut bottoms out and I can reach torque. This is after I have followed the attached instructions to make sure I am on a low spot on the cam. Shouldn't the lifter spring collapse some before the valve start to open? The lifters and valve springs are stock. 

Am I overthinking this? It doesn't seem right that the valves should open at all on the flat part of the cam.


----------



## PontiacJim (Dec 29, 2012)

The lifter will pump up with oil, as that is what they do. The plunger has a range of movement inside the lifter. If you had no pushrod tension on the plunger because you backed off the rocker arm nut, the plunger will rise all the way to its upper most range within the lifter body due to the oil pressure pushing it up (pumping up the lifter). When you are tightening your rocker arm nut down to spec, you are forcing the plunger deeper inside the valve body. However, there is a tremendous amount of pressure developed by your oiling system that is under the plunger. The plunger has to find its "place" within the valve body as you torque down the rocker arm nut. In order to do this, the oil under the plunger has to "bleed down" - squeeze out the un-needed oil through a small hole in the lifter that is keeping the plunger at its upper most range.

If you tighten the rocker arm nut down too fast, the force of the oil is fighting the pressure applied by the pushrod as it slowly bleeds down. The plunger is still nearer its top most range, not giving up its oil pressure quick enough to match your tightening down of the rocker arm nut, and the lifter acts as a solid holding the pushrod up too high (essentially making the pushrod longer than you need) which in turn (through the rocker arm geometry) forces the valve to remain slightly open because the lifter has not had enough time to bleed off the oil pressure - but should within a very short time.

OK, no expert on doing this but here is what I would do to get things right again - so take my advice with a grain of salt as they say.

I would not worry as to what position the cam is, ie low side of the lobe, and just torque the rocker arm nut down to spec. I would torque all the rocker arm nuts down to spec. Pull the coil wire so the engine won't fire, torque all the rocker arm nuts down to spec, then spin the engine a few times. Let it set an hour as any valve spring pressure on those lifters where the plunger is too high, will force the plunger to "bleed down." Come back and spin your engine a few more times, and let it sit another hour. This should normalize the lifters/valves. Check the pushrods/rocker arms to see if they have a little play/wiggle room. If they still seem too tight, I would get the No. 1 cylinder valves closed and on the low side of the cam lobe. Then back off the rocker arm adjusting nut while spinning one of the pushrods with my fingers. Note how much you have to back off the nut from its torqued setting. If you have to go 1/4 of a turn or more you may have some issues with the rocker arm geometry, ie milled head, incorrect pushrod length, worn parts, etc.. 

Another way to do this would be with the engine running. Do this for each cylinder - like you would to "zero lash" each lifter. Pull the coil wire so there is no chance of the engine firing up on you. Get the lifter on the base circle of the cam (lowest point) with the engine off and adjust each cylinder/pushrod to where you can just about spin it between your fingers. I am assuming that this is not at the point where the rocker arm nut has reached its torque of 25 ft-lbs. Do each cylinder the same way. Then reattach the coil wire and fire up the engine and go back and torque each rocker arm down to 25 ft lbs - BUT do this slowly so as to give time for the lifter plunger to bleed down and normalize. 

Oil will probably spray all over so be ready with rags. Some people mold some aluminum foil over the top of the rocker arm where the oil spurt hole is located. I use a set of clips designed to fit over the rocker (non-rollers). Keep a fire exstinguisher handy and don't let the engine run to long and get the exhaust manifolds too hot. If this works, do one side at a time, let the engine cool, then do the other side. If for some reason you find you have a valve still slightly open once you torque the rocker arm down to spec on the first cylinder, STOP, and back it off until it seats again. My guess at this point is that the heads may have been milled and your pushrods may now be too long - affecting rocker arm geometry and holding open the valve. If this is the case (and this is just a guess on my part), then you will need a pushrod checking tool which they sell aftermarket and follow the steps in determining the correct length you will need.

Hope this helps. :thumbsup:


----------



## Colorado67GTO (Sep 11, 2014)

Thanks Pontiac Jim for the extensive write-up.

I guess the only question I have is if the leftover oil pressure is strong enough to resist the torquing and open the valves while you are adjusting with the engine off, wouldn't the pressure just be restored when the engine was started, raising the pressure to the point where it would overwhelm the valve spring again?

I hope my questions are not annoying. I am just trying to understand before I make any changes to my valve train. I do have the parts to switch to straight studs and pollylocks, but that would mean ditching the stock drippers.


----------



## PontiacJim (Dec 29, 2012)

Colorado67GTO said:


> Thanks Pontiac Jim for the extensive write-up.
> 
> I guess the only question I have is if the leftover oil pressure is strong enough to resist the torquing and open the valves while you are adjusting with the engine off, wouldn't the pressure just be restored when the engine was started, raising the pressure to the point where it would overwhelm the valve spring again?
> 
> I hope my questions are not annoying. I am just trying to understand before I make any changes to my valve train. I do have the parts to switch to straight studs and pollylocks, but that would mean ditching the stock drippers.


Never annoying, that why we are all here - to provide opinions, advice, & learn. :thumbsup: Your valve spring tension has more than enough pressure to bleed down the plunger within the lifter as the excess oil is forced out. When someone talks about "zero lashing" their valves, what they do is back off the rocker arm adjusting nut (generally a polylock) until the lifter loosens up enough to produce a "clicking" sound. Once the lifter begins to click, you slowly tighten down on the adjusting nut until it stops clicking. Your engine may in fact run a little rough because the valve may be held open slightly UNTIL the lifter bleeds down. The rocker arm may begin to click again, and you tighten the nut down again until the clicking stops. You then allow the lifter to bleed down and it will either no longer "click" or it may click and you will do this again until it stops clicking. At the point the rocker arm stops clicking, you have found "zero lash." You then tighten the polylock 1/2 to 1 turn additionally to put the correct preload on the plunger. Finally, tighten up on your polylock and go to the next valve. (WARNING - This is assuming your rocker arm geometry is correct and you are adjusting your valvetrain on an engine that is already in driving/working order and not one you have done any major block/head cutting on and have not checked your valvetrain geometry/measurements from the beginning.) 

Now this is for adjustable valvetrains. Pontiac did not use an adjustable valvetrain, but rather, used a torque spec to tighten down the rocker arm nut to the correct value needed - which Pontiac engineers took into consideration all the clearances & tolerances needed to do this. Non-adjustable valvetrain just takes many variables out of the picture like adjustable valvetrain which needs to be regularly checked and periodically adjusted which most auto owners don't care to do, they just want to get in and drive.

For us hot rodders aimed at getting all the performance we can out of our engines, it is simple enough to make the non-adjustable valvetrain, adjustable. Polylocks is all it takes. They come in various heights and you can typically find a size that will allow you to fit them uder your valve cover. Other times, this is why you need taller valve covers, spacers, or thicker valve cover gaskets if the polylocks hit the top of the valve cover or even interfere with the factory oil drippers (which might mean removing them or using a non-dripper valve cover).

Going to the aftermarket ARP Big Block rocker arm studs provides for a much stronger set-up. Not only a better grade of steel, but you get a larger 7/16" diameter post that the rocker arm slips over. The factory screw-in stud is 3/8" where the rocker arm slides over. You can still use it of course, but if you start going aftermarket with your cam/springs and spring pressures & lifts begin to exceed factory specs, then you want to swap for the 7/16" BB studs - simple enough to do because they unbolt. However, you must make sure of 2 things: you will most likely have to go with a rocker arm that will fit over the 7/16" stud (remember, Pontiac's were 3/8"), AND you want to make sure you get a rocker arm that has a "long slot" at the pivot ball cup for higher lift cams so the rocker arm does not bind - which can bend pushrods, break studs, or other things no so pretty. I also look to make sure that the rocker arm balls have the small oil grooves in them when you use higher pressure valve springs or plan on spinning higher RPM's, ie using your Pontiac engine the way it was meant to run. :smile2: Some rocker arms do not have these and are simply smooth - fine for the stock engine or grandma. You want the oil grooves as these hold/channel oil to the rocker arm cup - which provides lubrication & helps to keep the rocker arm cup cool. When they do not have the grooves, high valve spring pressures and high RPM blasts can starve the rocker arm cup of oil and the next thing you know, heat builds up real quick to the point you may burn up the rocker arm - it may have signs of blueing of the metal from the excessive heat. Now you can be cheap and buy just the 7/16" oil grooved rocker arm balls and use your factory rocker arms, but I don't suggest this. Just purchase a new set of stamped steel - cheap enough and better insurance.

So back to your question. All hydraulic lifters have a range that the plunger can travel within the lifter body. They are designed this way to automatically and constantly maintain a zero clearance between the rocker arm & valve stem as thermal expansion changes the valvetrain tolerances with temperatures as the engine heats up and cools down & parts wear down. Oil/oil pressure from the oil pump fills the inside of the hydraulic lifter. The pressure pushes the lifter plunger up in its bore until all the play is out of the valve train. As the camshaft pushes on the lifter, there is a check valve/ball inside the lifter that closes to seal off the oil inside the lifter. Since oil is not compressible, the hydraulic lifter now acts as a solid lifter to open the valve. But, there has to be a means designed into the hydraulic lifter to allow some of the oil now trapped inside the to empty so that the plunger can again set the lash to zero on the next stroke. This leakage is called "bleed down." Bleed down is nothing more than a very small oil leak that is allowed to occur between the plunger and its bore inside of the lifter by building in a slight clearance. When this tiny amount of oil leaks out, it simply spills back into the crankcase to once again be part of the engine oil supply -and this cycle repeats over and over as the lifter rides on the cam. 

The plunger has a range of motion it works within. Factory/Cam manufacturers will provide a range in which the plunger needs to fall within called "preload." This is done by getting the plunger to its bottom most point (lifter bled down) and then backing off the rocker arm adjusting nut to allow the spring under the plunger to raise it to its "neutral" point, or center of the plunger travel. If the measurement taken falls within .020" - .060", then the preload is good. Outside of these values and you need to get longer or shorter pushrods to adjust to get the needed preload. This is how you compensate for heads/blocks being milled or even valves being sunk. Here is a better explanation from Crane Cams which gives you a step by step procedure: http://www.cranecams.com/pdf-tech-tips/hydro-lift.pdf

Hope this helps and clears a few things up. :yesnod:


----------

