zupanj
Well-Known Member
I fitted my tti headers to the engine the other night. The engine is fitted with 426-1 Indy hemi heads. The bolts supplied were 1" long and when I tightened them, they bottomed out before the header was tight against the head. There was maybe as much a 1/4" of space between the header flange and the bottom of the bolt head. So I measure the depth of the holes on the exhaust ports and they are 1/2" deep, the header flange is 3/8" and the gasket will be something, maybe 1/8". That adds to 1" and I can't figure out what is going on. I call Indy and they say 3/4" bolts will work fine and that the holes are tapped to 1/2" depth. I call tti and they can't figure out how that can be. The guy says he has a head in front of him and he never heard this before, then says 3/4" bolts would probably be OK. I come home last night with calipers I borrowed from work. The flange is 3/8", the holes are 1/2" deep, it makes no sense. Then I crawl down and look into the hole with a bright light. I looks like the threads only go in about 3/8" so that explains why the 1" bolts bottomed.
So here's the question. Would you use 3/4" header bolts to put the headers on or would you tap the bolt holes to be able to use 1" bolts. I can't see that the 3/4" bolts can have much bite, maybe 5/16" and that's my concern. Will that be enough. Threading the bolt holes can be a bit tricky and will delay the project but now is the time to do it if it needs to be done. So what do you guys think? By the way the 383 used 3/4" header bolts. I need to measure the flange on those headers tomorrow.
Jack
So here's the question. Would you use 3/4" header bolts to put the headers on or would you tap the bolt holes to be able to use 1" bolts. I can't see that the 3/4" bolts can have much bite, maybe 5/16" and that's my concern. Will that be enough. Threading the bolt holes can be a bit tricky and will delay the project but now is the time to do it if it needs to be done. So what do you guys think? By the way the 383 used 3/4" header bolts. I need to measure the flange on those headers tomorrow.
Jack