My hooker headers did not come with the y-pipe bolts. I see that the headers themselves have threads in them. Anybody know the size of the bolts needed?

 

Anybody? I'm assuming everybody got their y-pipe bolts but me?

 

Mine included grade 5 bolts for the collectors. I'm almost certain the thread is 7/16-14 (coarse) because I recall needing a 5/8 socket. You should be able to mock up the headers and y-pipe to confirm how long they need to be.

I imagine Hooker/Holley would be happy to send the missing bolts, or at least tell you what size they send.

 

I picked up a few of those bolts and tried them but they are not the correct size. They catch like one thread. Any idea what other size I should try? I called holley they said to try some 9-16 I'll try some of those.

 

That's weird... 9/16 thread seems like it'd be way too big. Maybe try 3/8-16? Should be super common too, they normally have a 9/16" head.

Are your headers ceramic coated? Is it possible the threads just have some paint and/or ceramic coating in the threads that needs to be cleaned out with a tap? I can't imagine they use metric or anything bigger than 7/16, that already seems overkill.

 

They are not coated . Just have the black paint on them. I mean I'm sure they will thread in if I begin to tighten them but they will surely cut the thread slightly bigger I can feel it, they are a little bigger then the holes. I will hit the home depot tomorrow and compare with the 3/8 16 bolts. I could take the header with me but I'm to lazy to remove it. Another option is to get some slimmer bolts and nuts and go that route. I'm pretty sure the bolts fell out of the box during shipping as the box was real beat up and taped up. Headers were in great shape and looked awesome btw..

 

Mine took 7/16 coarse thread bolts

 

I changed to aluminum gaskets and use the bolts that came with them I believe standard 7/16 coarse

https://www.autozone.com/exhaust/per...lts/467566_0_0