Exhaust options w/ 305 to 350 swap

[CaffeineRacer]

So I'm getting ready to drop in a new 350 engine into my 1982 to replace the 305 currently in there. Since this is an 82 it's got all that blasted AIR emissions crap on the exhaust manifolds. It's all rusted like crazy and will be removed along with the air pump once the new engine is put in. Also if one has never seen the exhaust systems on these later Avanti IIs, they are not true dual, the manifolds run into a sort of y-pipe that then runs to a straight intermediate pipe to the catalytic converter, from the converter there is another y pipe that splits into a dual system with separate mufflers and tail pipes.

So in looking around to exhaust options I had settle on using a set of the repro rams horn manifolds, which I can only find with a 2.5" collector outlet. http://www.speedwaymotors.com/Smoothie-Rams-Horn-Exhaust-Manifolds-Small-Block-Chevy-Raw,94194.html

That's probably a good size for letting the 350 breath, but presents a problem. The current manifolds on the 305 are a 2" outlet and and the y-pipe they feed into is 2" on the inlets and then run into a 2.5" collector and the rest of the system is then 2.5." I've blown any budget I might have had on the engine so going to a dual system is probably not in the cards.

So my question is this, where can I find a replacement for that 2" y-pipe that connects from the manifolds to the rest of the exhaust that is 2.5"?

[Gunslinger]

Any good speed shop should be able to fabricate whatever you want for an exhaust system. I have a complete 2 1/2" dual exhaust system with headers and Magnaflow mufflers and a GM Performance 350HO crate engine.

I don't know what transmission your car has, but if you have a 700R4 like I had installed, the bigger diameter pipes may cause some clearance problems with your neutral safety and backup light switches. I had to have a new mount fabricated for clearance. Whether that's an individual, car by car issue I don't know. Just be aware you might run into that.

Let that engine breathe.

[Avanti83]

Muck around in here and see if it helps. http://forum.studebakerdriversclub.com/showthread.php?74295-74-Avanti-SBC-T-56-2-1-2-quot-Exhaust-System-and-Undercarriage

I just work with the local guys. They said they would have preferred the car on their hoist but I can MIG so it was easier for me this way. I also posted the pipe prices.

If you still want a 2" "Y" pipe, I would guess Nostalgic Motors. Any exhaust shop can make a 2" - 2 1/2" adapter but I'll bet the "Y" pipe costs more than the 2 1/2" pipes I put on mine. If not Nostalgic, most any exhaust shop can make "Y" pipe but it will not be inexpensive.

Bob

Edited June 9, 2014 by Avanti83

[CaffeineRacer]

Bob, that is crazy cheap. All the shops I talked to won't do it unless they have the car in the shop, which I can't blame them. The only trick is going to be getting the car to the shop after putting in the new engine. Do they make clamp on reducers? That's the only temporary solution I can think of for running the new engine and manifolds with the old exhaust. Other option I guess is to just mount up all the old exhaust and run the car over to the shop that way. I hate to have to pay them to install the new manifolds then though.

I looked into getting a set of duals from Don over at Silvertone. I've heard great things about his systems, but boy they sure have gotten expensive (645 for the 2.25" system). I'm hoping the y pipe will be a more budget friendly solution. I'll have to see what a custom dual system would be from the exhaust shop though. It seems to me in looking and the current system you could reuse a pretty significant portion of it like everything from the muffler back.

Muck around in here and see if it helps. http://forum.studebakerdriversclub.com/showthread.php?74295-74-Avanti-SBC-T-56-2-1-2-quot-Exhaust-System-and-Undercarriage

I just work with the local guys. They said they would have preferred the car on their hoist but I can MIG so it was easier for me this way. I also posted the pipe prices.

If you still want a 2" "Y" pipe, I would guess Nostalgic Motors. Any exhaust shop can make a 2" - 2 1/2" adapter but I'll bet the "Y" pipe costs more than the 2 1/2" pipes I put on mine. If not Nostalgic, most any exhaust shop can make "Y" pipe but it will not be inexpensive.

Bob

[Avanti83]

If you want to use the local shop, I bet they could give you a ballpark price for the 2 1/2" based on the 2" OEM pipes. If the cost is in the ball park then you could price the cost of a tow/rollback to the shop or maybe your insurance would cover it.

I have Don's 2 1/4" on my 83 and I am impressed but just didn't want the cost on the 74.

BTW, my shop hit the 2 1/2" passenger side dead on from the 2" OEM pipes and all I had to do on the drivers side was cut off the flange end of the pipe and add the manifold adapter.

Good luck, Bob

Edited June 11, 2014 by Avanti83

[bos82]

just

Edited June 16, 2014 by bos82

[CaffeineRacer]

Bos82, was there more to you comment or was that "just" it?