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I am putting headers on my Trans Am and so I ordered new bolts from the GM dealership. When I installed the passenger side header and brand new GM bolts, they seem to be 1/16" too long (see pic). They are different from the bolt I removed when I took the exhaust manifolds off. The GM part number on the bag the "new" bolts came in says 11515758 which seems to be bumper bolts or timing cover bolts. On top of that I couldn't convince the parts guy that I needed 12 bolts. So I only have 8 in total.
You can see the "new" bolt installed; it is in as far as it will go (no I didn't torque it down but it is in tight). The next pic is of the original bolt I removed and reinstalled; it tightens the header to the engine nicely.
So, I need a solution. I could just try again and order exhaust manifold bolts (probably $3/bolt here in Canada) or I was thinking about buying some locking washers and using the bolts I have....but I will need to buy 4 more (I'm probably $24 into these 8 bolts).
What do you suggest I do?
"new" bolt
original bolt - only the bolt in the middle is tightened
It's not the right type of bolt and if you cut some off those you may have trouble threading them into the heads and you'll cross threading and you don't want that either.
It's not the right type of bolt and if you cut some off those you may have trouble threading them into the heads and you'll cross threading and you don't want that either.
To confirm, you are saying I should not use these bolts at all because they are the wrong application, correct? I think I'll call the dealership and see if they'll take them back.
Bob, thanks for the suggestion but I'm not inclined to do that.
To confirm, you are saying I should not use these bolts at all because they are the wrong application, correct? I think I'll call the dealership and see if they'll take them back.
Bob, thanks for the suggestion but I'm not inclined to do that.
What I'm saying is that I would be looking for an exhaust manifold bolt that will allow you to actually tighten the manifold to the cylinder heads whether it be ARP, Fastenal or whatever. When I purchased KOOKS headers it came with bolts and I believe those were completely threaded also so that must make a bit of difference. Take one of your bolts up to a Home Depot or Lowes and match them up to some quality stainless steel bolts that are slightly shorter.
thanks. I called the dealer back and she checked the part number with my VIN and the part they gave me is "correct" per GM. I also gave her the part number for 98-02 LS1 GM Exhaust Manifold Bolts (Set of 12) which is 11547135 and that DOESN'T match my car. I'm lost. Either way, the dealership is going to take the incorrect bolts back.
They have the 11547135 bolts and if it matches the bolts I removed when I took the manifolds off, I'll get them.
02-19-2019, 10:09 AM
Header bolt help 
