What is the size for the engine pulleys on sb chevy?

I bought a mid 70's 350 chevy sb without pulleys. I'm now installing.. need to buy bolts for both upper and lower pulleys. Does someone know the size I need for these standard water pump and crank pulleys please?

thx much.

 

3/8X24 on the crank ,5/16X24 for the fan by however long needed usually 3/4-1 inch.

 

5/16-18 x 1.00" long for the water pump. And 3/8-16 x 1.00" long for the balancer... Double check with what the others say... I could be wrong on the balancer bolts.

 

I'm getting 2 different answers here... is it 18 or 24?

 

small blocks are fine thread, big blocks are co**** thread on the damper.

Although if you have the engine sitting in frond of you, you could just look at the holes and see for yourself.

 

Don't you have an old bolt, somewhere in the coffee can, that you can stick in there and see what size??? If you've worked on enough stuff, you should have an eye for bolt sizes.

 

Gosh... thought someone would not off the top off their heads so I could swing by and pick some up on the way home (I'm at work).

"scuz the hell outta me!"

 

John Evans and Squirrel DING DING winner! 5/15X24 and 3/8X24 Crank 3/4" long water pump your length may vary. Later Ed

 

Ahhhh... thanks.