Header bolts - what type and size

[Indy]

Hi guys. I'm going to replace my headers soon, so I as wondering what bolts and what size I need. The headers don't come with any hardware, so I need to purchase some - so my question is: What size, type and where is a good place to order them online. Cheers, Indy.

[Indy]

I'm having a hard time finding good info on these bolts. I'm guessing they're 3/8"-16 (that's what other small block chevys use). What length should I get? 3/4"? 1"? Does anyone have a bolt lying around that you can measure?

Thanks for any help, cheers :beerchug:

[H2 Bill]

What brand of headers are you getting? Call the mfgr. and they should tell you what size to buy. There are different sizes of header flanges.

[Camou2]

I agree with H2Bill. If a mfg is building headers for an H2 then they should be able to answer your question. Unless you have a complete dealer service manual this info will be hard to find. You might try calling a local GM dealer who still services the Hummer brand and they should be able to find the answer.

[tomp]

I have new headers being shipped to me this week, so I can check the bolts for you when they arrive. I can tell you that they are metric and the length of the bolt is very very important. Go too short and you will strip the aluminum heads. Go too long and they will also strip the threads in the aluminum before headers are tight. It's best to use the bolts made for the brand of header you are going to use.