joe_padavano

There are no "spring bolts". I used stainless studs and nuts on mine. Original was bolts (sans springs). Note that unlike most Olds exhaust manifolds, these do use "donunt" seals between the manifold and the pipe. The correct ones are no longer available. I found some that were close. No, they are not the same as on an A-body. The flange and pipe diameter is different.

2blu442

I believe the bolts are the same diameter. So the bolts/springs should interchange.

2blu442

I didn't see Joe's post and had forgotten these used the doughnut.

smparr

I got some donuts off RockAuto that are supposed to be for this car, Felpro 2 1/8" ID. The shop manual made it look like the flange bolts had springs around them. Thanks for the clarification.

sysmg

I used Stainless Steel studs and brass nuts.

-Stew

smparr

The 1970 B/C Body uses a 2 1/4" exhaust right? The pipe going back on the car is 2 1/4" and it also says 2 1/4" on the clamps, but the 2 1/4" flanges with the round bolt holes I got from Thornton don't line up with the bolt holes on the S Manifold. I'm going to exchange the fixed round bolt hole 2 1/4" flanges for the slotted bolt hole 2 1/4" flanges and hopefully that works.

joe_padavano

The big car manifolds use different flanges than the A-body ones sold by Thorntons and others. I was able to reuse my old ones.

Oldsmaniac

Olds did use "spring bolts" I know on the 66 full size cars but you are better off with a stud kit and nuts.

smparr

What exactly do the springs do?

smparr

I can try to reuse the old flanges but the studs are pretty rusted.

sysmg

I think the springs in theory allowed for some movement of the exhaust pipe relative to the exhaust manifold, while maintaining pressure on the doughnut. However with all the exhaust heat, I would bet they lost tension over a number of years and were ineffective.