e3pres

I believe these are the heads that I have: 33417369

It is a GM Goodwrench crate engine.

Does anyone know if these use 3/8 or 11/32?

TIA,

cardo0

Those are the heads that where on mine when I bought it. I highly recommend umbrella valve seals. They are very cheap and work great with a stock or near stock engine. I installed mine right over the stock O-ring seals (new replacements of course). Should be plenty of room unless you have greater than ½” valve lift. They ride on the valve stem so don’t worry about any guide boss size. Just get the umbrella seals for stock valves. NAPA carries then for about $10 but shop around. Mine where made by Pioneer but sorry can’t remember part #.
Ya know my Goodwrench motor had ugly oil gobs on the intake valve stems when I pulled the heads. Smoked blue on cold startup too. Don’t know how they got so bad as I guesstimate less than 30k miles on motor? The lifter valley was still clean like new. Any ways all the fancy PC seals require machine work on the guide boss and really should have the brass valve guide installed for these as they run very dry. Late model corvette heads used a nice viton seal but still needs a machined guide boss. :chevy
And PAW only sells 11/32" valves for the sb chevy so thats what I'm gonna bet on. ;)

e3pres

Thanks. I'll check with NAPA today. :cheers: