prob with my 76' maro

[brutisrazutis]

i have a 76 maro with a 350. i have a set of edelbrock aluminum heads a weiand 142 cid blower with a holly 750 vaccume seconday advance carb. well i adjusted my roller rockers by backing them off till i hear them knock then tighten them till the knocking stops. then a quarter turn more. and tighten down the allen head lock screw. well i drive it around and all is good, but as soon as i give er hell down the street and then back out of it then everytime i accelerate after that my valves start knocking again. so i re adjusted twice more, and i felt good and then sure enough they started knocking again. what is causing this and how do i fix it? ummm its usually just the #4 intake and the #6 exhaust valve knocking. im guessing its just the roller rocker lock nuts are bad on those two valves. would rocker arm girdles fix this problem? any help would be greatly appreciated.

thank you,

brutis

[bigblock665]

My 79 did the same thing... Its your oil... When you accelerate the oil sloshes arround and for some reasion it cannot get to the rockers... but try next time, when it does it, stop off to the side of the road and let engine idle for like 30 sec. then listen for nocking sounds.... Mine went away but it always comes back under heavy acceleration!!!!

[MrPbody]

What cam? This symptom is typical of a worn cam lobe. If the same ones keep coming loose, mark them in a manner that won't "wipe off", and do it again. See if the poly-locks are moving, or if the pushrod is getting lower and lower into the block. If the locks aren't moving, yuo're probably looking at a cam going "flat".

If you have hydraulic lifters, a stud girdle is not required. They're for engines typically in the above-7,000 RPM range, which the hydraulics won't support.

Are the heads "out of the box", or built for your application? Another issue possible, is too much valve spring (intended for solids or rollers). This can prevent the hydraulic lifters from pumping up enough to be quiet. Spring pressure overrides oil pressure.

Need a lot more detail to nail this one.

Jim

[brutisrazutis]

i figured it out thanks 4 the help. it was my new heads. they have 64cc chambers and my old ones were 75cc chambers. so my compression ratio was to high.

[MrPbody]

So, that sound would be considered "pinging", not "knocking". There IS a difference...

Thanks for the info!

Jim

[crazy Jim]

geeezus

[MagicRat]

Originally Posted by brutisrazutis

i figured it out thanks 4 the help. it was my new heads. they have 64cc chambers and my old ones were 75cc chambers. so my compression ratio was to high.

Thank you for getting back to us on the solution.

Problem solved. Case (and old thread) closed!