Stud Mount Rocker Adjustment Issues

redneck15431

Member
May 13, 2006
80
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Hey all,

Over the winter months, I installed Twisted Wedge 170cc heads and did a cam swap as well as ported out my GT-40 lower myself. I initially followed the proper stud mount rocker adjustment after many searches online and everything was semi-kosher. Whenever I was figuring out the correct pushrod length, I made my own adjustable pushrod with a piece of all-thread I had laying around, two nuts acting as lock nuts, a tap to thread inside the pushrod, and properly calibrated digital calipers. So in order to get the proper length, I had to disassemble one of my lifters and flip the plunger.

I installed this lifter on the passenger side during reassembly of the engine and I've noticed over the past few months a more prominent "sewing machine" sound coming from the passenger side. More so when the engine is warm. It has not gotten worse over time, it's always been the same and I have not driven the car much at all due to the rainy summer we've had. I know for the most part, all roller rocker arms make some noticeable noise. So upon diagnosing and fixing an idling issue I've been having as well as an issue with the car running rich, I thought today would be a good day to readjust my rocker arms. I am using the stock covers that I ground out in many places for clearance, so my first thought was that I had a rocker ever so slightly contacting the valve cover. No evidence of anything contacting the valve covers. The rear most rocker arm felt like it had a little bit of play in it so I thought that was the culprit.

I readjusted all the rockers on the passenger side to the following procedure; Starting with the intake valve, the exhaust valve all the way open until it just starts to close as I am rotating the engine, obtain zero lash and go 1/2 turn, tighten down the poly-lock. Follow with the exhaust valve. Intake valve all the way open as I'm rotating the engine until the intake valve just starts to close, go 1/2 turn and tighten the poly-lock. I obtained zero lash by pulling the pushrod up and down until I couldn't feel any more movement. When I originally did this the first time, I obtained zero lash by twisting the pushrod until I felt slight resistance, and then did the half turn, tighten poly-lock.

So I put everything back together and started the car and heard all kinds of racket. Very loud "sewing machine" noise. I let the car run for maybe 30-45 seconds maybe hoping that the lifters needed to pump up but it didn't seem to go away, so I shut it down, restarted it for maybe 20 seconds and shut it down again. Even though it was not a lot of work, I was still quite disgruntled by the fact that I have to tear it apart again. My question is am I missing something here? Should there be some other procedure I should be following for readjusting them once they are installed? Could my lifters be weak, or the one weakened from me disassembling it? I appreciate any and all input.

Thanks!
 
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Intake goes full open and just starts to close... Adjust the exhaust
Exhaust valve just starts to open... Adjust the Intake valve

If you wait for the exhaust valve to fully open and close slightly you are most likely not on the base circle of the intake lobe and this will cause problems just as you have described.