Header Bolts

General engine tech -- Drag Racing to Circle Track

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BobbyB
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Header Bolts

Post by BobbyB »

I have a reworked set of AFR165 heads that have a few helicoils in the exhaust bolt holes. What header bolts (or studs) are recommended, stainless or carbon?
What should I put on the threads?
The headers on the car were installed years ago with 3/4" tread carbon steel header bolts into iron heads. The short carbon steel bolts worked great and were easy to install in the tight Comet engine bay.
I called AFR, they said anything is fine, with no particular recommendation.
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Re: Header Bolts

Post by mag2555 »

If the car is driven on the street in the rain I would go for stainless studs for the holes that are Helicoiled.
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Re: Header Bolts

Post by lewy-d »

I know lots of people use Helicoils. However a king sert or other solid thread repair might be a better fix. folks tend to really tighten header bolts.
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Re: Header Bolts

Post by gruntguru »

lewy-d wrote: Thu Jul 05, 2018 4:06 pm I know lots of people use Helicoils. However a king sert or other solid thread repair might be a better fix. folks tend to really tighten header bolts.
How often have you seen a Helicoil fail from over-tightening?
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Re: Header Bolts

Post by swampbuggy »

Personally i believe in employing studs (instead of) bolts whenever possible or practical. Common sense should tell us that there is less wear and tear on the threads in the hole. If it was mine i would apply a little neverseize on the stud (or) bolt threads threading into the cyl. head holes. JMO, Mark H. :)
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Re: Header Bolts

Post by 77cruiser »

I think anti-seize should be used on all bolts threaded into aluminum.
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Re: Header Bolts

Post by swampbuggy »

ALWAYS--for sure--w/o fail--everytime, aluminum threads will self destruct if given half a chance. How many of us have seen spark plugs that did not want to back out of an alum. head where never seize was NOT used ? Mark H. :?
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Re: Header Bolts

Post by tenxal »

In a tight engine compartment, studs make everything worse. A high quality steel bolt with anti seize is all you need. Schoenfeld Headers makes bolts with a nice 5/16" hex head that are pretty slick.
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Re: Header Bolts

Post by Geoff2 »

Stainless bolts, with anti seize.
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Re: Header Bolts

Post by rfoll »

I have had my share of header gasket leaks, but I have never had a header bolt loosen up or back out. I always use never seize on aluminum threads.
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Re: Header Bolts

Post by norm »

Use as long a bolt as possible, the more thread engagement the less chance of stripping.

A lot of times i see the bolts that are shipped with the headers and they are barely 1X the diameter engagement.

Also i just use RTV no gasket
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Re: Header Bolts

Post by lefty o »

tenxal wrote: Fri Jul 06, 2018 8:19 am In a tight engine compartment, studs make everything worse. A high quality steel bolt with anti seize is all you need. Schoenfeld Headers makes bolts with a nice 5/16" hex head that are pretty slick.
those small head bolts from shoenfeld are awesome!
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Re: Header Bolts

Post by tenxal »

lefty o wrote: Sat Jul 07, 2018 1:59 pmthose small head bolts from shoenfeld are awesome!
Yeah..been using them for a while, now. Good stuff.
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Re: Header Bolts

Post by Schurkey »

Duplicate, sorry.
Last edited by Schurkey on Sun Jul 08, 2018 3:50 pm, edited 1 time in total.
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Re: Header Bolts

Post by Schurkey »

MOST (not all) stainless bolts are about equivalent to Grade 2 farm-store junk. Some are almost as strong as Grade 5. ARP makes high-strength Stainless bolts, and I guess you can get some fairly high-strength stuff from other suppliers.

"I" would use SAE Grade 5 or Grade 8 "Header bolts" with the reduced head size--3/8 hex on a 5/16 or 3/8 bolt shank. I've also been known to use socket-head cap screws, if that helps with tool access.
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