I have been frustrated by valve train noise for 10 years on my 350... I changed cam & lifters, rockers, & pushrods and adjusted and re-adjusted valves about 10 times.... Inevitably I end up with one randomly tapping again before too long. I have adjusted them a full turn past zero lash... but the noise keeps coming back. The cams have been relatively mild. I have had a Comp XE268 cam in it but switched to a Howards Street Force 2 hoping it would be easier on the valve train and be quieter....
The heads I have on the engine have 76cc combustion chambers and PRESS-IN STUDS. RE: pushrod length, I had checked with both Comp and Howards if stock length pushrods were ok. In both cases they said stock length was fine.
Other than a surging issue under minimal load that I am working through, engine runs strong...
QUESTIONS:
1) Is stock pushrod length okay? Cam is 455/465 lift Rockers and push rods are stock and only a few yrs old...
2) I'm wondering if the Z28 valve springs I have (good for.55 lift) are pulling the stock press-in rocker studs out little by little and that's why the rockers keep loosening up. My heads are reworked heads--one cast in 73 and the other on 75...with what I assume are original press-in studs. Any thoughts on this?
3) I'm considering these heads from Summit that are similar to what I've been using for 10 yrs except they have screw-in studs that can't pull out and 72CC combustion chambers slightly smaller than my 76cc chambers. My current static compression ratio is 9.1:1 with the 76cc chambers. Any idea how much the slightly smaller chambers would affect the compression ratio? Still want it to run good on 91 or 93 octane..
Summit Racing SUM-152123 Summit Racing® Cast Iron Cylinder Heads for Small Chevy | Summit Racing
The heads I have on the engine have 76cc combustion chambers and PRESS-IN STUDS. RE: pushrod length, I had checked with both Comp and Howards if stock length pushrods were ok. In both cases they said stock length was fine.
Other than a surging issue under minimal load that I am working through, engine runs strong...
QUESTIONS:
1) Is stock pushrod length okay? Cam is 455/465 lift Rockers and push rods are stock and only a few yrs old...
2) I'm wondering if the Z28 valve springs I have (good for.55 lift) are pulling the stock press-in rocker studs out little by little and that's why the rockers keep loosening up. My heads are reworked heads--one cast in 73 and the other on 75...with what I assume are original press-in studs. Any thoughts on this?
3) I'm considering these heads from Summit that are similar to what I've been using for 10 yrs except they have screw-in studs that can't pull out and 72CC combustion chambers slightly smaller than my 76cc chambers. My current static compression ratio is 9.1:1 with the 76cc chambers. Any idea how much the slightly smaller chambers would affect the compression ratio? Still want it to run good on 91 or 93 octane..
Summit Racing SUM-152123 Summit Racing® Cast Iron Cylinder Heads for Small Chevy | Summit Racing