Tedd Thompson

I'm not going to make Cool April Nights again this year(about 2000 entry car show) because my exhaust manifold bolts gave it up again ,opposite side this time.My damn car sounds like a John Deer tractor.

Are there any bolts that work better than others ,maybe stainless. I think we used # 8 harden bolts last time. This is on my 55...Tedd

oldcutlass

Are they breaking, I would think GR8 would be plenty. Stainless has the tinsel strength of a GR2 very soft and they gall easily.

Tedd Thompson

Ya, flush to the head, may have to pull the head but am hoping there is a little tit that we can get a nut welded to, didn't work on the left side we ended up pulling that head,wish they had both leaked at the same time. I'm wondering now if some old bolts were used for this to happen twice....Tedd

oldcutlass

If you remove the remaining bolts, can you use a die grinder on the broken ones to get the manifold off and there should be some bolt left to get them out. I've reused manifold bolts and never had tehm snap off, you think they might have been over torqued?

Tedd Thompson

Anything is possible, the build on this car would go by pitifully slow one or two weeks then the next week parts would come in and three or four of us would put in a couple 12 14 hour days often doing work in relays. Plus it was 12 years ago, hard for a old man to remember.

jaunty75

Sorry, but I just broke out laughing and have to correct this. "Tinsel" is what you put on your Christmas tree to make it look like icicles are hanging off of it.

When talking strength of metals, or anything else, being stressed in tension, it's tensile strength.

oldcutlass

Lol, thanks Jaunty for the spelling lesson. Hmmm, SS bolt Xmas ornaments, they bought pet rocks.

Hairy Olds

I have used stainless bolts on my 67 442 for years and they work great. Torque specs are low to hold the manifolds on.

Tedd Thompson

Thanks for the replies/ suggesting, still haven't got it tore down ,Just found out at least two bolts/studs are missing but a small punch put into the hole stops at where the head starts. This may take a while kinda booked up with health issues now.....Tedd

Octania

Stainless works well on your exhaust manifolds, as set forth above. Do not over-torque. AS for the galling of SS, this is a well documented phenomenon, we are going thru this at work at this time, I am educating the engineers there how this works. Typically, it occurs with a nut and bolt of the same grade of SS, and NOT with an SS bolt into cast iron. Once the fastener galls, it is welded to the nut on a molecular level and more turning only makes it worse. Twisting off or cutting off are your choices. Our problem is that the bolt heads are inaccessible, held by a cavity that is a little too large to hold against the torque to twist to fail, so we get a spinning bolt and a ruined hub. I am trying to train them how to deal with the issue, but they seem unable or unwilling to grasp the concept. But, I digress.


If you have broken that many, it sounds like either overly torqued, or NON-original crappy material. Used FACTORY fasteners might be preferable to new crappy fasteners. I have twisted off MANY an exhaust bolt, but this is in working on exceedingly crusty MI parts cars, and motors salvaged from the river [apparently].

Go with OEM fasteners or SS.
Either way, use plenty of ANTI SIEZE on them. Avoid future grief.

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