kelly bakies

what is the original exhaust manifold bolt grade that was used on a original 1970 442. I have looked around the internet and I just get what everybody would use. I would like to use the grade what the factory used.


thanks in advance

Allan R

Can't go wrong with grade 8. It's pretty much a standard.

lshlsh2

I don't know if you can but how about stainless? With the difference with heat expansion I don't know ir it would work or not. Maybe someone will chime in.

Larry

MDchanic

I use stainless. Works great. The only possible problem is that stainless bolts tend to back out a bit more readily than non-stainless, so it's a good idea to retighten them a few times, just to be sure.

Of course, none of this answers the OP's question...

- Eric

BlackGold

I don't know what grade the factory used, though they did use a sheet metal locking device which kept the bolts from backing out.


After getting sick of blowing out header gaskets, I finally went to the hardware store and bought some grade 8 bolts and installed them with lock washers and high-temp loctite. They haven't backed out since, and that was a lot of years ago.

Run to Rund

Factory used grade 5. The best stainless you can probably find is somewhat less than that.

oldcutlass

Most stainless bolts are equivalent to gr2. They also tend to gall.

Lady72nRob71

I found this out the hard way 10 years ago. I got SS bolts for a pool filter clamp that would always rust. I thought they would be strong, but I stripped one using hardly any torque at all. It was a pain to hack saw it off and I replaced them with GR8's and oiled them well to retard rust.

TripDeuces

ARP Stainless steel bolts are rated at 170,000 psi.
Grade 8 is rated at 130-150k psi.
It is possible to have stainless above grade 8 but not the stuff you buy at the hardware store.
The way my exhaust bolts usually go I'd have to say they are grade 5 at best

I never use stainless bolts without anti-seize on them. Just not worth it. They even gall when used against other stainless although I attribute a lot of that to cheap offshore stuff without rolled threads. If you ever use the ARP stuff you'll be amazed how well made they are. You can spin the nuts on by hand every time.

Octania

ARP Stainless steel bolts are rated at 170,000 psi.
Grade 8 is rated at 130-150k psi.
========================
wow that is impressive for SS


It is possible to have stainless above grade 8 but not the stuff you buy at the hardware store.
The way my exhaust bolts usually go I'd have to say they are grade 5 at best
====================
ck the head marks
3 radial lines = grade 5
6 lines = grade 8
SS is not graded this way
https://www.boltdepot.com/fastener-i...ade-chart.aspx

I have had good luck with A.S. coated factory Gr 5, handy Gr 8's, and SS. In any event use A.S. and locking tabs like the factory did, and of course if you put gaskets between the manifold and head you can expect to re-torque.



I never use stainless bolts without anti-seize on them. Just not worth it.
==========================
never use ANY exhaust bolt w/o anti-sieze on it. If you value your time at all.


They even gall when used against other stainless although I attribute a lot of that to cheap offshore stuff without rolled threads.
==========================
SS galls WORSE or more frequently when used with the same grade SS mating component. It's a molecular level welding process, pretty much irreversible [unfixable- adding lube after galling does not help], and it just happens at times. Coatings and differing grades of SS are tactics to minimize this PITA phenomenon.


If you ever use the ARP stuff you'll be amazed how well made they are. You can spin the nuts on by hand every time.
==========================
You don't say?
nuts spin right on.
are there fasteners that this is NOT true for?
We use quite a bit of SS at work, and with wax coated fasteners, it's not bad.

Greg Rogers

I use new grade 5 good quality hardware store bolts and I replace them every time I take them apart. Reason is they tend to shrink and corrode. I recently removed the left side exhaust manifold on my Vista which I believe had never been off. I got real lucky and It came off using a assortment of different 6 point sockets/ wrenches. (13, 14mm and 9/16). The good quality bolts seem to have a thicker head. I use them with a flat washer and high temp antiseize. I know they don't look right and are in plain view but it's a driver. I also don't use the retainers. It's amazing how hard they can be to get off after 10 years or so.

pogo69

SS is not needed for anything on your olds unless you take it out on the high seas

Octania

Said the man who does not live in MI

Do you not have road salt and rust in CT?