Help with valvetrain.

[Justa6MB]

I have what I believe to be some valvetrain noise that's setting off the knock sensor above 5600 rpm. I have a 210/215 hydraulic roller cam and GN1's with adjustable Scorpion roller rockers. I borrowed a valve spring checker from a friend but there's no way it will check them in the car. I had recently set the valves at 3/4 past zero preload. How I did this was I backed off the rocker arm, then tightened it down while spinning the push rod in my fingers. I assumed zero was when I couldn't move the push rod with my fingertips. I've read a couple of posts with similar combo's where it was recommended to go to 1 full turn or .050". I'd like other opinions to confirm or deny this. Also I've been reading the info that came with the cam and I'd like to check everything else that could cause noise I can without pulling the intake or heads such as:
-Push rod length ok?
-Push rod to guide plate clearance? What should this be and could this cause noise?
-Do I have the correct valve springs? How can I tell?
-Rocker arm to head, stud, valve spring retainer clearances?
Thanks
D

 

[Buick Mark]

The spinning the pushrod thing never worked for me, that all depends on how much oil, or grip your finger tips have on the pushrod. If you have oil on your fingers or pushrod, the pushrod will stop spinning sooner than if your finger tip has a decent grip on the pushrod. How I do it is make sure the cylinder your doing is on the compression stroke (both valves closed, lifters on base of cam lobe) back off the adjuster on the rocker till the pushrod is loose, the slowly turn it in till you start feeling resistance, do this a few times to get a feel for it, when you got the feel for it, turn the adjuster another 1/4 to 1/2 turn to set pre-load. This procedure works for me, the only other way to do it would be to remove the intake to actually see the pushrod plunger when your at "zero" lash before you set the lifter plunger preload.

 

[autoguy]

Couldn't you also place a feeler gauge between the valve stem and rocker and check it that way?

 

[bison]

First determine what lifters you have. If you have comp 885's you should run them with zero preload/zero lash. Adjust them by finding compression #1 tdc abd do ex 1,5,6, in 1,2,3 then rotate 360* and do ex 2,3,4, in 4,5,6. You don't go till they stop spinning. You go till there is zero by moving the pushrod up and down till the lash is gone. There is no way to verify spring pressures without testing them. At least pull off one and have it tested. You will need to measure tge installed heights to get a general idea of rhe pressure. Installed height checkers are available from any mail order supplier. If you have lifters other than 885's then you can run preload. I would run 1/4 to 1/2 turn. You may need to pull the intake to determine the lifters. You can't guess or assume any of this. It all has to be verified.

 

[Justa6MB]

Ok thanks guys. So I believe I have 853-12 Comp Lifters. I will set them as described with some preload for now, then during our long cold winter I will likely tear it down deeper. Thanks a lot B. Any other suggestions which could cause kr at high rpm?

 

[Justa6MB]

I'd like to remove and test the valve spring pressures. I have the tool to remove the springs from stock heads - but what's the best way to remove them from GN1's? The springs have a pink stripe on them. I suppose that's code back at Champion? Anybody know which springs they might be so I can check them to specs?

 

[Justa6MB]

Bump??

 

[bison]

You can by a spring removal tool from any of the big online suppliers. Just bolt it down after removing the rocker arms. Ive had to slightly modify the one i used and using an extension pipe made it a lot easier to compress really strong springs. If the springs are up over 350lbs open most will have a hard time without a long lever.