what's the thread size for a chevy small block? I went to the hardware store and they gave me a 7/16 -14 tap. I hope this is the right one.

 

Thread size for what?

 

my bad I thought i put it in there, a head bolt

 

If you use a 9/16" socket to get the bolt off, you have a 3/8 thread, which is 3/8-16 NC.
If you used a 3/4" socket, to remove the bolts, then you have the correct tap.
I've never removed the heads, but now you can tell for yourself.

 

that's a **** poor way of telling thread sizes, but alot of people that don't know any better use it. head bolts on a SBC are 7/16-14 and have a 5/8 hex. a 3/4 hex will most commonly have a 1/2 bolt under it, either course or fine threads.

 

hmm, sound advice, i'm only going by what the r3dnecks have taught me over the years, and it was good advice at the time (not in reference to automotive...).
a die run over the bolt is a good way to check it.... if you have a tap and die set already though you wouldn't be asking this question...

 

i cleaned up all the threads and stuff. I just didn't know if there were very many variations in head bolts

 

A drill gauge and thread pitch gauge, both available at your favorite hardware store for about $4 each, are an even better idea, since you won't damage the threads when you guess wrong on your first try.

 

open end wrench is way faster and more idiot proof, something some members here need. then all you need to do is figure out the pitch and that can usually be done by looking.

 

oh, yes, I meant with an open end wrench, rather than a socket...

Anyway, there aren't too many variations on a thirdgen, this method should work, if in doubt, a thread gauge can help.