When I was installing my AZS&M headers, there were a few primaries that I could not fit a 1" bolt around. Obviously, go with 1" when you can, but use 3/4" when you can't.

 

1 inch Breslins here. They are high priced but went I ahead and bit the bullet and ordered them. Now after installing them I willl never use another header bolt again. I used to have regular bolts back out all the time. I've heard friends complain about the stage 8 locking system. These stay tight. I rechecked them one time after installing the headers and haven't touched them again.

 

Which bolts could you not get them in? I think the hardest one was the second bolt on the #2 primary. That is definitely the hardest to tighten as well!

Normally the primary is too close to the bolt to get a good 12 point wrench on it but for some lucky reason, when I bought a new 12 point Craftsman wrench, the closed end was offset just enough when it was manufactured that I can fit the wrench on the bolt and tighten it pretty good. Talk about lucky!!

 

I can't remember off the top of my head which ones were giving me grief, but the problem was with getting the bolt threaded, not tightened. A few times, the 1" bolt was just a bit too long and I couldn't get it threaded without fear of crossthreading. The 3/4" slid right in there. The stage 8's are nice b/c they have the tiny little head that you can tighten with an allen wrench, making installation and adjustment much easier.

 

i ordered some from cmotorsports last week, arp 12 pt.
i think i might have gotten the 3/4 "
u guys talking 1" total length, or 1" of threading?
i need to go home and check,,,maybe need to get the longer ones..
-Jason

 

i use ARP 12pt with 1" of threading and 5/16" head on my jethots (thick flange), part # 100-1209 in black.
the 5/16" head makes it easier to get a wrench on it next to the header primary. i still have to grind the head of my wrench though, thanks to jethots totally crappy design of their headers, they should have indented the primary to give the bolts more room. jethot headers totally suck.

ive used Stage8, and Breslin already, and so far the ARP's are better. they both had fitment problems, the heads of the bolts were too big to fit next to the jethot primary, and could not get a wrench on them, and the allen key on the stage8s kept stripping. one of the breslin bolts actually broke in half.

 

Generaly when you are talking bolt length, it is the threaded section. You should have 7/8 inch of thread in the head. With a flange and gasket 1" is good and will give you more thread contact than a 3/4 inch bolt. Especially being Aluminum, this is more threads "grabbed" the less chance of stripping. And that would suck!

 

i just called combination motorsports and they don't carry any 1" arp header bolts,,where can i get some?

 

www.summitracing.com

ARP part 400-1209

type that in the part # lookup. They are stainless steel and are $28.69

I love summit Jegs sux!