Exhaust options for 68 B-Body with 78 400

[erikcroissant]

Hello all,

I have a 68 Coronet with a 78 400 from a C-Body swapped in. It currently has the original 400 manifolds with about 2 feet of pipe attached to each side- not a great setup. I’m looking to upgrade to a full length exhaust, probably the TTI, but they don’t have a full exhaust that fits my specific manifolds. Should I buy factory 383 manifolds so that I can order a TTI exhaust? Anything to look out for? Open to other options as well, though I’d prefer to keep manifolds over headers.

Thanks.

Erik

 

[1968rt]

Buy a set of B body HP manifolds. Anything from 67-72 should fit fine. Just make sure you give the manifold numbers to TTI while buying the exhaust. The clocking is different on certain years.
68 manifolds with TTI 2.5 H pipe here.

 

[4speed68rt]

Show us some pictures of that 68 Coronet and those manifolds, please.

 

[Don Frelier]

I would look for 68-69 HP manifolds.
That way the car has sort of original equipment.

 

[casey henson]

This was the primary reason I got HP manifolds for my 77 Chrysler. So I could use 2.5 inch TTI head pipes

 

[PurpleBeeper]

My 2-cents? If you're not building a show car, just build a semi-custom exhaust. You already have 2 ft of pipe coming off of each manifold, right? Assuming that pipe is at least 2-1/4" or 2-1/2", right? Just buy the exhaust you want (factory, pypes, TTI, whoever) and have a muffler shop slice the front of the pipes off and transition into your 2 ft. pipes....Or, better yet, just buy mufflers and tail pipes and have a muffler shop build a custom h-pipe, x-pipe or no cross-over or whatever between your 2 ft pipes and the mufflers.

 

[1 Wild R/T]

Hello all,

I have a 68 Coronet with a 78 400 from a C-Body swapped in. It currently has the original 400 manifolds with about 2 feet of pipe attached to each side- not a great setup. I’m looking to upgrade to a full length exhaust, probably the TTI, but they don’t have a full exhaust that fits my specific manifolds. Should I buy factory 383 manifolds so that I can order a TTI exhaust? Anything to look out for? Open to other options as well, though I’d prefer to keep manifolds over headers.

Thanks.

Erik

Erik
What part of California?

 

[casey henson]

My 2-cents? If you're not building a show car, just build a semi-custom exhaust. You already have 2 ft of pipe coming off of each manifold, right? Assuming that pipe is at least 2-1/4" or 2-1/2", right? Just buy the exhaust you want (factory, pypes, TTI, whoever) and have a muffler shop slice the front of the pipes off and transition into your 2 ft. pipes....Or, better yet, just buy mufflers and tail pipes and have a muffler shop build a custom h-pipe, x-pipe or no cross-over or whatever between your 2 ft pipes and the mufflers.

the factory outlet size on these manifolds is 2-1/8. I couldn't live with that on mine.

 

[PurpleBeeper]

the factory outlet size on these manifolds is 2-1/8. I couldn't live with that on mine.View attachment 1354455

If yours is a 512" stroker motor with a roller cam & 2-stages of nitrous.....nope, too restricting. If yours is a relatively stock '78 400 out of a C-body....2-1/8" true dual exhaust would be an upgrade.

 

[Dave6T4]

Usually, the driver's side exhaust manifold for a C-body is way different than B-body piece to clear steering on the C-body. As others have said, get B-body HP manifolds. They have 2 1/2" flanges. 440's used 2 1/2" head pipes with these, while 383's used 2 1/4".

 

[erikcroissant]

Erik
What part of California?

I’m in the Bay Area

 

[1 Wild R/T]

I’m in the Bay Area

Probably find a set closer but I have a few sets of hp manifolds in Modesto.

 

[casey henson]

Usually, the driver's side exhaust manifold for a C-body is way different than B-body piece to clear steering on the C-body. As others have said, get B-body HP manifolds. They have 2 1/2" flanges. 440's used 2 1/2" head pipes with these, while 383's used 2 1/4".

Interesting I did not know that the 383's actually necked down to 2-1/4. Good to know. I knew they had the same manifolds.

 

[Dave6T4]

Interesting I did not know that the 383's actually necked down to 2-1/4. Good to know. I knew they had the same manifolds.

Back in the day, 383 RoadRunner guys used to put the larger GTX exhaust on their cars to gain a little advantage.

 

[Some Car Guy]

I thought the neck down took place in the tail pipes even on 383 cars. 2.5 to the muffler and 2.25 tail pipes coming out. The 383 cars didn’t get the h pipe and that was considered an upgrade for them.

 

[oldbee]

I thought the neck down took place in the tail pipes even on 383 cars. 2.5 to the muffler and 2.25 tail pipes coming out. The 383 cars didn’t get the h pipe and that was considered an upgrade for them.

Yup, no h-pipe. But DaveT is correct, 2-1/4” all the way back from the manifold.

 

[OKDart]

Back in the day, 383 RoadRunner guys used to put the larger GTX exhaust on their cars to gain a little advantage.

Do you remember if it required any modification? I have a factory 2 1/2" H pipe that was bolted to a 440, and plan on putting it on a 383.

 

[Dave6T4]

You will have to cut a small slice out of the "H" pipe and reweld it, since a 383 is slightly narrower than a 440 due to its shorter deck.

 

[Don Frelier]

You will have to cut a small slice out of the "H" pipe and reweld it, since a 383 is slightly narrower than a 440 due to its shorter deck.

Or a band clamp...