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Do all exhaust manifold bolts have a triangular shape to the threaded end of the bolt?

Is there a reason for them being so shaped?

I've been told several things, such as using regular grade 8 hardware will (best case) seize or (worst case) cause the bolt hole in the head to crack, because the triangular form to the manifold bolts allows them to expand and contract.

I don't know if it's true or not, but I sure need to know if it's safe to use some good grade 8 or harder bolts or do I really have to suck it up & pay $213 for a set of exhaust manifold bolts....I just spent $700 on heads, I really can't afford to break em yet..

Thanks for any help.

I would definately use bolts intended for exhaust applications. Some are triangular, some are hollow, some have grooves. $213 seems outrageous for a set of bolts. Where did you get that price?

Ford dealership in my city.... I was like

All the parts stores tell me the same thing "bring in a sample and we'll go through the hardware bins"

I used some grade 8's on mine. Haven't had any problems.

Thanks for the replies.

I haven't been able to find anything anywhere else for the specific 'exhaust bolt' application, which is kind of weird.

Any thoughts on a used set of bolts from a boneyard 2.9?

lilBro wrote:Thanks for the replies.

I haven't been able to find anything anywhere else for the specific 'exhaust bolt' application, which is kind of weird.

Any thoughts on a used set of bolts from a boneyard 2.9?

I see no problem using used ones they last forever the onl;y thing I think id do to used ones is bead blast em so they look new