What size header bolts?

[daveh]

Hey guys I'm getting conflicting opinions.  At are the header bolts on a 340 small block 3/8" or 5/16"?  And should they be 3/4" or 1" long?  I thought it was 5/16".

What would be best overall?  Should I get longer bolts for the outside holes going into the water jacket?  I'm installing TTI headers that has a 3/8" flange. 

Anything you can help me with is appreciated.
Thanks

Dave

[Chryco Psycho]

5/16 coarse thread , 3/4" long

[69ChargerRT]

CP knows it all

[daveh]

Thanks guys I appreciate it.

Dave

[Chryco Psycho]

if you have the thick 3/8 flanges as in TTi headers you can use 1"

[daveh]

I think that's what I want to do.  Thanks