Hey all
Trying to help out a fellow Olds owner. He's got a 1970 Olds 98 4 door hardtop he's rebuilding. He'd like to go with dual exhaust and I don't know enough about his application to give him advice. I know the late 1960's used an S manifold on the drivers side, was that still used in 1970? Then was the passenger side the regular T manifold with the crossover blocked off, or would a Z fit on this car/chassis? Or was there something else used on the passenger side? John

 

If he uses the cast iron manifolds with a large W (402295) and Z (402294) cast into them, they are the most easily available and are the ones the factory used on dual exhaust cars.

 

I know that's the case on the A-body, but due to the cross member location I didn't know if they would work on the full sized car.

 

You are right, there were different manifolds on the full size cars.

With duals, the right-hand one is 398708 (common) and the left-hand one is 393229 (only installed on 88s with the W-33 engine).

Looks like some hot rod ingenuity is required.

 

Yes, the 1970 B/C manifolds were the same as '65-'69. He'll need the Thornton reproduction.

- Eric

 

I have a set of dual exhaust manifolds John off a 65 Starfire. Those would work. The right has a factory cap on the center dump one normally used as a cross over. the left is the S manifold to clear the steering gear.

Larry
lemoldsnut@aol.com
541-815-4363

 

x2

Either that or some custom fabrication. But; as you know, folks on our site only speak highly of the Thornton reproduction.

 

Thanks Larry, his name is Jerry and I sent you a PM with his contact information. He hasn't been on here much, but here's an old thread of his.

https://classicoldsmobile.com/forums...olds-98-a.html

 

That's true for the 1970 cars, but the "S" manifold for dual exhaust applications was used on more than just the W33 motor in years prior to 1970. In any case, this is reproduced and readily available, so no "ingenuity" is required, just a credit card. FYI, unlike the A-body manifolds, these S and T manifolds do require donuts on the outlets. Naturally, the correct ones are no longer available. The best available ones from Walker are smaller than the opening and require bending the metal ring to make it stay in the manifold. Also, use Walker Acousti/Seal (P/N 35959) to avoid leaks. Finally, the trans shift linkage is different on dual exhaust cars to clear the driver side pipe. This is a rare part, so either plan on having a whoop-de-do in the pipe or fabricating a linkage rod.