Hey Jim,OK. Then my money would be on the poly lock being incorrectly adjusted just a little too tight and holding the valve open just enough so it does not seat tightly.
When you back the poly lock nut off on the #7 intake and test for an air leak,and that does it, I would "zero lash" all the lifters/rockers on that side and then do the other side to ensure whoever installed them knew what they were doing. This is done while the engine is running for the best results - in my opinion & experience. Others adjust the lifters differently than with the engine running.
You also want to make sure you have the correct length body on the poly lock - they can be long or short. Look at the allen screw. It should not be sunk into the poly lock, nor should it stick way up and out. You want the allen screw to be somewhat flush at the top or just a thread or 2 above.
Here are a couple posts to read through that will help.
torquing rocker armsI am putting my 326 back together and I have question on torqueing my rocker arms. The manual says to torque to 20#. Do I just go down the line and torque them all to 20 or doe the need to be preloaded and if so how do you preload.www.gtoforum.com
Compress lifters by hand - normal?Hi gang, long time no post. I had my motor re-built quite a few years ago (2012). It sat till I finished my resto in 2015. Strong running, no leaks, plugs burning clean. I have been getting considerable lifter tap from the left bank and was preparing to do a cold engine overlap adjustment using...www.gtoforum.com
Rocker Arm / possible collapse lifter??Hello all - I have a conundrum here. My new complete rebuilt motor for 68' GTO, 400 MT came back with ticking noise I attributed to a loose rocker arm or bad lifter. After numerous consults, I adjusted all the rocker arms per the "twist push rod until tension and snug down 180deg. - NOT the...www.gtoforum.com
I checked # 7 cylinder today…valve cover off. Made sure it was at top dead center for that cylinder. Hooked up leak down tester. Noticed that the air was coming out around the intake pushrod hole as well. That seems odd to me…cracked head Or blown head gasket? Not losing any antifreeze or compression.
I took rocker arm off completely and no change on leak down…still at 5%.
Guess I know what my winter project is