First of all, I'd like to say hello to all the members... I'll post in the new member section if you want to say hi.
Anyways, I have had some problems lately with rocker clatter on my 1969 gto. I spoke to a gm parts dealer (who ironically recently rebuild a 66 goat) and found out that technically, it is nonadjustable and should only require torquing everything down to 20-25 ft-lbs. Well after doing just that, there was severe play still. I ended up having to add a washer and torquing to 50-55 ft-lbs to eliminate this problem... or so I thought. A few days later the chatter came back and is only increasing (I checked the setup and it didn't slip). My two thoughts are that either the lifter isn't getting enough oil and is likely getting stuck or that it is the cam. I have since done a check and am pretty positive that the cam is fine. I guess my main question is, does anyone have any suggestions on getting to the lifters and more importantly, a schematic on the engine? I'm a little on a time crunch and don't really want to wait for shipping of a manual (I already have the parts to replace the lifter). Thanks all, and hello!
Hi, Welcome to the forums.
I believe those should be adjustable hydraulic lifters. To adjust that style you would turn the motor over till both valves were closed (@TDC of that cyl) then loosen the rocker nut to start, then while rolling the push rod between your fingers with one hand, tighten the rocker nut with the other hand just until you feel the slack taken out of the push rod (gets hard to turn), then tighten an additional 1/2 turn. Do all 8 cyls and you should be set. If you had solid lifters, then you would adjust the same way, sept when the push rod just gets tight, you would back the rocker nut off and use a feeler gauge between the rocker tip and the valve stem and adjust to the cam`s specs.
Post some pics when you get a chance!
I wonder if he put in the wrong engine then. The rockers are held down by a bolt/nut combo that both have shoulders to them. I have gone through all 16 valves and adjusted them, however there is a limit due to the shoulder (hence the non-adjustable part). Even when I add a washer there to give space, which I shouldn't have to do, the one valve quickly deteriorates again within 5 minutes so it either has to be the cam falling apart or the lifter. When I tested it I took off the valve cover off, disconnected the distributor and had a friend turn the car over. When this happened I had equal movement between the bad valve and all others around it, which I have been told by an engine mechanic is the test to find out if it is the cam or not (if its the cam there shouldn't be equal movement). This means that it must be the hydraulic lifter, however I am not entirely sure how to get to it. I'm really hoping for some guidance towards a manual or schematic to rebuilding a 400ci pontiac engine so that I can at least feel like I have a safety net when I start pulling components.
As for pictures I will take/post some when the weather clears up. 280+ days of sunshine here and NOW it gets cloudy.
I'm actually positive it's the right motor after speaking with the local pontiac parts rep. It's the 69 400 ci engine... they still have stock nuts for the nonadjustable pieces. Maybe your thinking of the '70 engine?
If you read close it actually is recommending that you switch to an adjustable setup, then goes on to explain how to adjust them. I am not sure which ones are adjustable, but I do know that mine isn't =). A lot of people have been known to use chevy adjustable studs with lock nuts.
I don`t read that....I see.."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."
I read that as even stock rocker arms need to be adjusted.
I have had good luck using stock Chevy Big Block Studs and nuts. This will make the Pontiac valve train adjustable. adjust them a 1/4 to 1/2 turn after the slack is removed from the push rod while on the base of the cam.
The problem isn't the adjustability part... I have added spacers to it only to quickly have the rocker gain play again. This means that something in the geometry is giving way. The more I push down on the rocker, the more play goes in. This isn't something that can be fixed with just adjusting a nut. All I would like is some guidance towards an engine schematic or repair manual if anyone has any suggestions...
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