400 Pontiac Valve Adjustment Question??

I recently removed the heads off my Pontiac 400 block and was wondering about the valve adjustment. The heads will be ready in a week and when I re-install them I would like to know from the membership on the proper way to set them up. The motor has a crane cam in it with hydraulic lifters. When I installed the heads before I went by the cam install instructions. Would it be the same as a sb chevy. Turn the crank till the lifter is down, tighten the rocker till you take up the slack on the push rod, then give it 1 1/2 turns to preload the lifter??? To me this is the easiest way and these Pontiacs a a bit finicky when it comes to valve adjustment. Thanks


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A. Starting with #1 cylinder, turn the engine over until the exhaust pushrod just begins to move up.

B. At this point, stop and adjust the intake valve on the same cylinder.

1) Tighten the rocker until you can roll the pushrod between your thumb and forefinger with the slightest bit of resistance.

2) At this point tighten between an additional quarter to half of a turn.

C. You have now adjusted the #1 intake valve. You will now want to turn the engine over while watching the same intake pushrod that you just set, it will go full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. By following this procedure, you are assured that both of the lifters are at the base circle of the cam and that there is no additional pre-load applied to them from cam lift at this point.

D. You are now able to repeat this procedure on the remaining cylinders.

4.Re-install your valve covers and your valve adjustment procedure is finished

If this is a stock pontiac head, the proper way to adjust the vales is to torque the nuts to 20 ft. pounds.

sam-missle

Thanks Greg that is the same way I adjusted them before. But the difference is the 1/2 turn part. You know I'll do it that way again and I'll only give them a half turn. I think I gave them a full turn and a half before. Well I'll let ya's know by the end of the week how it runs.

If any of the valve train components have been changed, such as the cam, you can't use the stock adjusment method. You need to use a positive locking nut (poly-locks), because the stock type nuts won't hold the adjustment.

as long as the valve length is at the right height, assuming all else is good, the stock valve adj. will work. cam or no cam. just make sure of your plunger travel.

sam-missle

That only works if he has locking rocker nuts. Pontiacs don't. From the factory they are torqued nuts. You bottom out the nut on the stud and torque it down.

I've done a few pontiacs with very mild cams that I kept the original nuts and torqued them down, but its a crap shoot, especially if the heads or deck have been trued up. I built a 389 that way once and ended up bending a pushrod, bending a rocker arm, and lifting a pressed stud up out of the head about 1/4". Ever since then I just went with polylocks and haven't had any issues. They're cheap.

50 dollars worth of polylocks save you alot of heart ache down the road. cole

The lock nut is torqued to the bottle neck of the stud or the end of the threads. If the aftermarket cam has a different base circle, as they usually do, the plunger in the lifter is either pushed too far, or not far enough. In either case, the set up is not correct!

Right... assuming things gets you in trouble. There are some instances where torquing down stock nuts is fine, but if anything is different, you need locking rocker nuts

The "performance" Pontiac heads have screw in studs and guide plates from the factory, the only down side is the 7/16" to 3/8" bottle neck stud.

Several companies sell the correct length studs to convert those heads to the stronger 7/16" studs w/poly locks for adjustability. Last set I bought was from H-O, I think they're out of business now.

This isn't necessary if the cam is relatively mild. But once the cam requires shift points to rise to 5000 RPM or more, the stiffer studs come into their own.

Well first off the cam came with locking nuts it was a kit Crane Energizer and its a mild one. Second of all I have discovered the my problem with the heads. There was what I thought a exhaust leak when I started the car after winter storage. When I pulled the air breather off the noise got louder. My thought was a bad intake valve. I did the compression test and had one cylinder down 20 compared the the rest of the cylinders. I figure I might as well pull the heads port & polish them and get the heads & valves done. As I'm pulling them apart I noticed the intake gaskets was burned. Then it dawned on me that when I rebuilt the motor in 2002 the gasket kit had a larger opening for the auto choke. I went back to the supplier and he told me that was the right gasket and to just block the hole with a piece of gasket. He said this would give me more horsepower. Now I figured he was to lazy to get me the right gasket and him saying "More Horsepower" I was sold. So I had to cut the heat pipe for the auto choke so now it was open but the gasket blocked the exhaust from going under the intake manifold, so I thought. Eventually the heat burned a hole in the gasket and the exhaust noise was coming from this small pipe that goes to the carb. So I really didn't have a valve problem after all but the heads had to be removed to change this gasket anyways. The kit I got from Napa has both intake gaskets so this won't be an issue in the future. What I have to do is find the instructions for the cam and do the same procedure again. Thanks guys I know these Pontiac motors are sensitive so thats why I started this thread to get some feedback on this. Thanks to all excellent stuff and I really appreciate it!!!