so ive had a rattling exhaust valve for a while and turns out it wasn't just the valve guide.... the guide is completely disintegrated and it hogged out the stem hole. so I guess im gonna be doing a head swap. I got a set of heads from a 79 that didn't have the smog stuff so I guess that's getting deleted. anyway my question was is it worth it to shave them a few thousandths or just slap em on? like would I really gain anything by doing that like more power or would it just make a higher compression ratio? im gonna be rebuilding the 79 heads before I put them on anyway ( valve guides, cleaned, valve seat refinish, valve faces etc.) just wanted to know if it would be worth it to shave em down or not.


thanks

 

Talk to your machine shop / engine builder and see what they think based on the heads you have. in theory shaving the heads would up the compression of the motor which would give you more power.

 

If you have a mid 80's and up 318 they used the notorious "Swirl heads" which had a piston that didnt come all the way to the top of the cylinder. The heads were flat on about half the bowl to help bring the compression up and and for the "swirl" etc...The older heads on this type of 318 would lower your compression so you would def want to shave the heads to bring your compression back up. Not sure what set up you have. I just put a set of worked 360 heads on my 318 which previously had the swirl heads. I had to put flat top pistons in it (they come to the top of the cylinder) to bring my compression back up. I also shaved the heads a bit as well.