I have a 1985 2.8L v6 camaro and I did a compression test on all of the cylinder's after putting a new head on and having the other machined. When cranking I only got 90psi on all the cylinders and the pressure slowly dropped on all of them. The engine was cold when I did the test. Do you think I mis-adjusted the valves in the cylinder heads? I used a chilton manual and I found top dead center and then adjusted the correct valves in order. When I could no longer spin the push rod I then adjusted the nut by turning it 3 half turns which would be 540 degrees like the manual suggested. When the car has been sitting a while the engine makes popping noises and is difficult to start which I think its backfiring.

 

I normally go just 90 degrees past the pushrods dragging. Seems like you went 720 degrees, which is way too far. That would hang valves open.
Also, compression testing needs to be done as soon as the engine is cool enough to touch after having been driven to normal temp, and all the spark plugs should be out at the same time, and the battery fully charged.

 

And the throttle blocked wide open.

If it wasn't, go back and try again.

 

Sorry it seems I have confused you. I turned the nut half of a circle 3 times. So that makes 1.5 full rotations that I turned the nut. Which is 1.5 turns like the chilton manual suggested I do. Before the passenger's side cylinder head had problems I tested the compression with the same method and I got 150psi then. So if I use the same method again I was just expecting to get the same results.

 

I have just adjusted all of my valves again today. I did the jiggle up and down technique on the push rods instead of the spinning technique. And I did about 1.25 turns after the lash had been removed. When I got it all back together it now has quite a bit more power than it did before. I do not have a compression tester now but it is working much better than before.

 

You're close enough, then.

Lash adjustment from the factory is typically 1.5 turns down from zero lash (with the lifter somewhere on the heel of the cam). That leaves PLENTY of upward travel in the lifter plunger to take up long-term wear of the various valvetrain components. For a performance build most guys only go down 1/4 to 1/2 turn from zero lash so that the valve won't hang way off it's seat, ready to get smacked crooked by the piston, if they over-rev and float the valves.

Just thought I'd mention that in case you were wondering why you rarely hear of so much pre-load being recommended on a performance-oriented message board like Thirdgen.org. Performance guys use the much skinnier spec they do for different reasons than the factory 1.5 spec.

A further FYI- somewhere around 2-3 turns down from zero lash you bottom the lifter plunger inside the lifter body. Anything more than that and you start to mechanically lift the valve off it's seat (everything is solid-stack in the valvetrain at that point), which would instantly send cranking compression readings straight into the toilet since the valve would no longer be resting on it's seat.

 

Thanks for your help I have been testing my car on some big hills here in Washington today. Before the valve adjustment that I did today there is no way it would make it up a hill it was like the car had 50HP. Now it feels like its making a good amount of power. I am happy I am a member of thirdgen no one I know knows anything about cars and I would never have known about the jiggling up and down of the push rod for lash if I had not come here. I only set valve lash at 1.25 to try and make sure the valves would seat properly since I have already tried 1.50 turns. But the reason that probably did not work was because I used the spinning push-rod technique.

 

Yeah, it can be tough to tell the exact "zero lash" point by spinning the pushrod. It's a very subtle difference when contact is made. When you have done a bezillion of them, you get a feel for it (and it's more accurate when you do) but for somebody doing it the first time, better to jiggle until it don't jiggle no more and then set lash down from there. Gives a more positive feeback to the fingers to know when you're near zero lash than the spinning method.