im building a 390 stroker engine. i was measuring for pushrod length today and notice that the rocker arm sits too far back from center for my liking. i have always thought you wanted your rocker to pivot on the center of the valve stem. instead it rides on the back part of the valve. i did try and shim the rocker stand, but it didnt look to help very much. for those that have run into this problem, is it ok that the rocker rides back there. this engine will be a twin turbo setup so i wanna make sure this is going to be ok.

 

hmmm, nobody has any input on this?

 

What heads..??..rockers ??

 

Did you mark the valve stem and rotate the rocker through the full valve lift? The stock rockers scrub the valve stem and move from the intake side to the exhaust side during the open cycle. This movement should be centered, which means it will start somewhat to the intake side even if properly set up. Raising (shimming) the rockers will move the pattern to the exhaust side of the valve stem.

 

i havent had a chance to rotate the engine because i was measuring for push rod length. i guess the issue is if i buy the pushrods i ''think'' i need, then have to shim the rockers, i will have wasted my money on pushrods. but, id rather have it right the first time. im out of town with work ATM so i cant do anything till i get home. any1 else have a idea?

 

That's why guys usually buy the adjustable pushrod length checkers to be able to dial in the length and rotate the engine to check the pattern.

 

get the adjustable checking tool and measure for a correct length push rod.you can get them in any length.you are right wanting the rocker riding on the center of the valve stem.

 

PR length sets proper lifter preload. Very important to do FIRST. Then shim if needed for optimum wipe....

 

lol thats what i was doing. i have the tool. was checking for pushrod length. thats when i noticed the position on the rocker to valve stem. i didnt think of rotating the engine tho.

 

the thing that baffles me tho is im using ls3 heads and rockers. shouldnt they line up? only thing im changiing is the cam. i would think stock stuff would line up.