55.2-59 57 GMC 550 370 V8 exhaust gaskets

[prateroad]

Might be in the wrong place but does anyone know where I could get a set of exhaust gaskets for this truck. My research says it's a 370 Pontiac or Olds engine.

[geezer#99]

That’s one mean looking truck!
Pop the hood and devour all the Prius’s on the road!

Contact Bob.
He might have what you want.
It’s a Pontiac by the way.

https://www.bopparts.com/1957-pontia...asket-set.html

There are others too.

https://butlerperformance.com/i-2445...9498-sh-1.html

[mr48chev]

My education for the day. I knew that the smaller trucks ran Pontiac V8 engines but this says that there should be an Olds engine in that truck. Only used in those larger trucks according to this info https://www.jalopyjournal.com/forum/...re-371.606092/

They should look like this https://www.ebay.com/itm/15274972038...C_6h4k297cm0UI These are correct for 57/58.

[geezer#99]

Post a pic of the motor.
Always visual clues to decide what it is.

[mr48chev]

Originally Posted by geezer#99

Post a pic of the motor.
Always visual clues to decide what it is.

That would be a good idea as you don't know what someone might have done on a work truck of that era.

[prateroad]

I think I found some at local parts store, we'll see when they come in. Had to cancel order, asked parts man and he said center manifold bolt holes are horizontal, mine are vertiical. Everything I saw on fleabay for a 370 has horizontal holes. I might have to make my own.

[geezer#99]

C’mon, don’t tease us!
Where’s the engine pic?

[prateroad]

Well, I see it on my end.

[geezer#99]

Any info I found since last post says it’s a Pontiac 347.
Try that for gasket matching.

[dsraven]

if you could draw a rough outline of what your manifild gasket may look like that may help. if it has had a leak for quite some time the gasket surfaces on the manifold or head may have been eroded. when you get to it, ensure to lay a straight edge on the gasket surfaces of the sealing areas to check for warpage. if you cant find a gasket you can always make one from the right gasket material.

[dsraven]

the gm heritage center may be able to tell you what the truck originally came with for options etc and engine size. dunno if that would help.

[dsraven]

is the 347 and 370 not the same engine family? heads and manifolds would interchange so gaskets would be the same then?

[mr48chev]

Your engine is indeed Olds based rather than Pontiac.

This is a photo of a 57 Olds 371 engine in a 57 Olds.

The smaller trucks had Pontiac based engines but the 550 and larger had the Olds based engine.

[leegreen]

I have nothing to contribute - but I'd like to see more pictures of that cool truck!

[dsraven]

mr48 may be correct. if you check an olds 371 engine the exhaust manifold bolts are vertical.
here is the wikipedia outline
https://en.m.wikipedia.org/wiki/Oldsmobile_V8_engine

couple of pics in this thread
https://www.jalopyjournal.com/forum/...149650/page-19
another motortrend write up with some pics of exhaust bolt configuration
https://www.motortrend.com/how-to/09...ngines/photos/

[prateroad]

Ok, here you go. Bought off fb. having trouble getting 2 center bolts out. Heated with torch, put wax and ATF on them and manifold. Goin to let them soak until tomorrow.

[mr48chev]

There is also a difference between 57-58 and 59-60 gaskets from what I have found on line for Olds 371 gaskets. That finding Best brand gaskets on Ebay/

This add for an Olds 371 exhaust manifold shows that the bolt holes are vertical. https://www.ebay.com/itm/35556013431...Bk9SR7ydoLaoZA

It's really not rocket science and I can't understand why some are arguing about it.

[geezer#99]

Awesome truck!
What’s it run for a transmission?

[prateroad]

I think it is 5 speed, actually has auxiliary transmission to run huge pump in back.It says to run pump only in overdrive.

[prateroad]

Would it be ok to heat head where top exhaust bolts screw into it? I only have those 2 bolts left to go.

[leegreen]

back in the day I worked in a shop that did a lot of exhaust work, we'd routinely heat the casting bump over a hidden bolt end. oxy acetylene, not a huge flame and stop at the very first hint of dull red. carefully try to get it to break loose then go back and forth a bit to loosen the threads, as soon as you can, send some penetrating oil up the shaft of the bolt or into the crack between head and manifold then send the bolt back in a bit to carry some oil into threads. this with a wrench, not a power tool.

if nothing will get it loose it is preferable to cut the head off the bolt with grinder cutting torch etc than to risk breaking the bolt in the threads. once the manifold is out of the way you can heat the head around the bolt, quench the bolt with penetrating oil to shrink it then vice grip it.

If it does break off at the threads, watch some videos of how people get broken bolts out of LS heads by welding a washer and nut on.....we have done several of those in the last couple years and it works. (with aluminum heads!, I'd cut a copper 'washer' from some scrap pipe to use as a shield to prevent welding the iron nut/washer to the cast iron head surface, or try drilling it out )

[leegreen]

heat at those points

[dsraven]

if you can drill a small hole through the bolt and out the void space behind it, heat the casting with a fast heater like oxy/acetylene so the casting heats up faster than the bolt thats broken off, then as it cools enough to allow lube to be squirted in the hole without burning off, do that. walk away for the night and come back the next day. it usually works and the small hole can be drilled out to accept an easy out, after squirting more penetrating oil into the hole. I think what happens is the two parts heat and expand at different rates so the head casting expands bigger than the bolt and this cracks loose any rust etc. the bolt isn't usually galled in the hole when it was initially installed, it is just broken off and rusty on the contact surfaces between the bolt and the head so it has become one part kinda. once the rust is "broken" sometimes the thing comes out easy. also, when drilling, use a drill bit that is meant to turn counter clockwise cuz sometimes the drill will jam on the bolt and the whole thing will unscrew from the hole. had it happen lots of times

[dsraven]

do you have the head off?

[dsraven]

a nut can be welded to the broken off bolt if you are any good at welding. allow to cool well before trying to remove after welding as usually the bolt heats up and expands to be tighter in the threads when hot.