SBC Valve Guide Clearance

I run a 23 degree alloy headed sbc with an alloy rodeck block. Just wondering how much valve guide to valve stem clearance I should have? I'm worried about the two middle exhaust ports that are next to one another and do get a lot of heat because of that reason.

 

a rule of thumb is .001 on anything that's less than an inch and .001' per inch on anything over but this doesn't apply on blown alky. .005' or .006' on rods , mains and pistons.

As for your question . I set the guide on big chiefs at just free no drag (about .001') they are really long and this seems to work good. For the small block I'd give the center 4 exhaust the next reamer so .002' .

Just my opinion.

 

haha. a question i can possibly help with. I run a alum headed 372cid SBC, blown alcohol.

My Dart heads were set at .001 (tight side) and grabbed #3 exhaust on my first full pull down track (read: more heat). They are now .003 onthe exhaust, and .002 on the intakes.

 

Do you guys run valve stem seals?

 

NO seals required in a blown car, you intake is under pressure so you wont be sucking any oil down the guide.

 

Agreed. no seals on either side.

 

No, no seals here either.