size of outer diamature of valve guide chevy 305 tbi 1988 for valve seal size?

Answer 1

Chevy's don't have replaceable valve guides per say. The holes for the valve stems are bored and honed in the cast iron cylinder head to fit a particular valve stem. If you find that you have an exhaust stem clearance over .003 you need to have the heads removed, the and guide holes drilled and honed for new over sized bronze wall or hardened cross hached steel replacement guides pressed in.

I also has a personal 305 with loose guide holes @28,000 miles. Chevrolet made these heads as thinwall castings with no nickel in them. I hate to say it but they were "weak sisters" to say the least.