sunnfish

I have a 86 with cast iron heads. When I was putting my engine back together I was adjusting the lifters like normal tighten until the push rod is snug. Then you give it one half to three quarter turn. When doing this I could see the push rod open the valve, is that normal? Will the oil flow out until it is closed?

C409

..... Don't start the engine ... you adjusted the valves wrong ... ignore the pushrod spinning technique ... turn down the adjusting nut until all lash is JUST gone at the rocker , then turn it down to your preferred pre-load or at least 1/4 turn ... turn the engine by hand (breaker bar) ... don't use the starter ... when the exhaust valve starts to open , adjust the intake valve ... turn the engine by hand until the intake valve has fully opened and then is ALMOST closed to adjust the exhaust valve ... I usually readjust while running after the engine has gone through a couple of heat cycles ... loosen the adjusting nuts one at a time til you hear it start clattering ... turn the nut down til it JUST stops making noise ... then again turn down to your pre-load setting ........

cudamax

Try this
http://www.camaros.net/forums/showthread.php?t=189632

John A. Marker

If the valve is opening when you tighten the nut you have the valves too tight. BACK OFF on all the nuts so they are loose and start again.

Adjusting valves on the Corvette:

1) Remove the spark plugs. This makes it much easier to turn the engine by hand.

2) I believe that the nut in the center of the bottom pulley on the balancer is 5/8”. Use a six point 5/8” socket to turn the engine over by hand to line up the timing marks. Place a finger in the spark plug hole for plug #1 as you turn the engine over. You are trying to determine if the engine is on compression as you line up the marks. If you feel the air pushing against your finger as you line up the marks, you have compression in cylinder #1. Align the timing marks.

3) Now adjust the valves as follows:
Intake #1, 2, 5 and 7 then adjust Exhaust 1, 3, 4 and 8.
Note: If you are not sure which valve is the intake and which is the exhaust, look down at the exhaust manifold. The exhaust valve will be right above the exhaust pipe for the cylinder you are looking at.

4) Turn the engine 360 degrees and line up the timing marks again. Now adjust the following:
Intake 3, 4, 6 and 8 then adjust Exhaust 2, 5, 6 and 7.

You are now finished with your adjustment. I usually tighten the lock nut 3/4 turn after adjusting to zero lash.


The above directions is using the standard twist the rod until you feel resistance. Years of doing this always left me uneasy not knowing if the rod was solid and by finger and thumb were slipping because of the oil. This works very well and I now use it 100% of the time -came up with by Forum Member JoeC

[I]BTW, I tried something a little unconventional on adjusting hydraulic lifters. one thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. so I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. {place the feeler gauge between the top of the valve stem and the rocker arm.} When I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. at that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. if you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...

again, thanks for all your help - take care -

JoeC
[/I]

Cliff Harris

I think that if the valves opened then the lifters will leak down, which invalidates all the "normal" adjusting procedures.

This is what has worked for me: I measured the distance from the end of the rocker arm stud to the top of the adjusting nut and found that all of mine were very close to 0.200". After I pulled my heads off I set all the rocker arms nuts to 0.200" and everything is peachy.

I think the only way to get a truly accurate adjustment is hot and running. I made a little aid to do this without getting oil all over the place (it tends to run down the rocker arm and flip off the bottom end):

cudamax

Easy way with no mess
http://www.australiancorvettes.com/d...valve_lash.pdf

sunnfish

Thanks for all your info. I did do just what you wrote and when I went to give it that final one half to three quarter turn I could see the valve move. My last adjustment I did the feeler gage method. I used a .oo1 gage tighten until I could feel it touch then I came down that half turn if I seen that valve move I went back maybe one quarter turn. I just felt this was the write thing to do. The engine runs great and I don't have any lifter clatter.

John A. Marker

Very well done! Glad that it is running well.

project C4

the object of the game is to get the lifter plunger at 1/2 of its travel when the lifter is on the base of the cam lobe. On the last motor that I set the intake was off so I could watch the lifter plunger travel. the middle of the plunger travel ended up being somewhere between 1/4 and half of a turn or 135 degrees.