3400 Exhaust Manifolds on a 3100

[3100 MPFI]

I got under my sisterinlaws car and took some pics of the stock 3500 exhaust setup.

Here is the front. I am under the front of the car. You can see the oil filter, and the starter on the right. The exhaust goes down the front, and over to the passenger side. The place where the exhaust goes through on the passenger side is where the stock W-body motor mount goes.


Laying down on the ground on the drivers side is where I took these pics.

You can see the tranny pan on the left side of the pic. The flex joint is where the front pipe connects to the rear pipes. and you can see the rear manifold pipe coming in at the back of the subframe.


And here is a better pic of the Y-pipe where the 2 ends meet up.

[Sidewinder]

The 3500 manifolds seem to be of a very similar design to headers, albeit they are routed under the car and the cylinder exhaust ports gather into the collector pipe well before the S&S headers would.

I'm going to take in some photos of the manifolds and see if the exhaust shop would be able to route them for me. I'm thinking I will have the pipe run around the side of the engine (where the stock one does roughly) and have the two hook up to a Y pipe with flex tube (if I need it) before the downpipe. If not I'll probably have to go with the 3400 manifolds, we shall see.

[torq455]

yes, they are header like. they do collect within about 6 inches after the ports. i like the y-pipe. i think if i had that, i wouldn't bother with headers!

[Sidewinder]

yes, they are header like. they do collect within about 6 inches after the ports. i like the y-pipe. i think if i had that, i wouldn't bother with headers!

Yeah that was kinda my thoughts, I think they would be closer to headers. However I can't say I know a whole lot about exhausts, but I'm learning.

[Sidewinder]

This is quite possibly a noob question, but since I am a noob when it comes to exhaust I guess I could be forgiven. I was thinking that since the 3500s are header style this may be possible. Would the 3500 rear manifold bolt in place of the front manifold, or are there differences?

If it can, I think that will make it way easier for the exhaust shop to rig up a system depending on how close it gets to the rad. This will only work with the 3500 manis since they don't use the crossover.

Would that even work?

[Superdave]

This is quite possibly a noob question, but since I am a noob when it comes to exhaust I guess I could be forgiven. I was thinking that since the 3500s are header style this may be possible. Would the 3500 rear manifold bolt in place of the front manifold, or are there differences?

If it can, I think that will make it way easier for the exhaust shop to rig up a system depending on how close it gets to the rad. This will only work with the 3500 manis since they don't use the crossover.

Would that even work?

Yep, they're interchangeable...

we're working on putting 2 front 3500 manifolds on a 3400 swapped Sunbird.. just need the flanges.

[Sidewinder]

Well I finally had a chance to go over to the stealership and see what they wanted for 3500 exhaust manis. They definitely weren't $60...

...in fact they were double what you guys would pay in the state apparently. They wanted $127 each, which with taxes is somewhere around $290 for both of them brand new. So thats not happening.

I'm going to have a look around at the local yard and see if I can find any, otherwise I will either get 3400 manis and port them or just port the 3100 manis or something.