I just removed my #48 heads & removed the vavlesprings. The heads appear to be cut in the area of the spring seat, but no shims, or valvespring seats. The guy I am rebuilding my engine with is use to Chevy engines and thought there should be valvespring seats(or at least shims). Are they required?

Thanks,

Ken

Don't have any shims on my heads or the other set under the bench

They could have been cut to allow for a taller valve.

No. Pontiacs don't "come" with shims. Big block Chevys DO, at least under the intake springs (.015" thick, hardened), as the exhaust have the "rotator" under them (on most, but not all). Small blocks, like Pontiacs, did not come from Chevy with them.

Shims are used to restore the installed height when the seats and valves have been ground, moving the valve "up" toward the rocker arm. It is also common among certain builders to "stack" shims under springs to achieve exactly "equal" spring pressure from one valve to the next. Whether or not that particular effort is necessary is debatable.

Jim

My engine has shims.

No shims from the factory.
But most shops check the hieght along with open/closed pressures.
Then use different thickness shims to equalize the diff's.
IMO, should be done whenever use'n aftermaket cams and springs, etc.

You should seriously have 2nd thoughts about using this guy. Or at least hand him Jim Hand's book on Pontiac motors. There are other very serious Pontiac specific issues like interior oiling that need to be looked into. My builder may have done way more Chevy motors, but at least he was pretty darn "up" on Pontiac motor specifics. I just added to his knowledge (like introducing him to the BOP Vitron main seal, he was used to modifying Caddy seals) as opposed to trained him from scratch.