Hi folks. I'm looking for some opinions please. I've got a 67 Cutlass Supreme convertible, 330 high compression, 4 barrel carb. I'm replacing the factory single exhaust with the dual exhaust setup I got from The Parts Place, with whatever mufflers that came with. This is aluminized steel, not stainless. I am thinking that the pipe that connected one side to the other in the single exhaust setup provided some sort of functionality (exhaust pulse, etc) that the H and X pipe do. I've got my own TIG welder setup so I can do the welding. I'm thinking about adding in an H pipe. Nothing is installed on the car yet.

For a stock build, factory dual exhausts, and being more concerned about low end oomph than top end:
1. Leave it alone?
2. Add an H or X pipe?

I'm leaning towards the H pipe. I'm also thinking about how this could get in the way, and would like to hear suggestions about placement as well as clamping ideas like the band clamp, ball flange, and v-flange.

If this has all been covered in another posting feel free to send me that. Thanks for your time reading this and your feedback.

Sean

 

I would add the H pipe. It took the drone out of my 72 Cutlass when I put the twin turbos on it years ago.

 

I agree H pipe and cap off the right forward manifold outlet.

 

I ran true duels, your not going to see a lot of improvement with a crossover for the street. You can always add one later.

 

I don't think the H pipe adds any noticeable power if any at all. It will get the annoying drone out and make the car a lot more pleasant.

 

I hear drone is caused by those mufflers that are flat on the top & bottom (like flowmasters). The traditional mufflers that are oval seem to be better when it comes to the drone.

 

My vote, keep it stock, you probably got stock mufflers as well... It will be less hassle and a better fit if you bought a stock setup for duals.

 

Ditto.
I converted my '67 CS to a 2 1/2" stock type dual exhaust using muffler shop parts,
stock type replacement mufflers, pre-bent pipes and all.
Pretty much like what you bought.
Very pleased with the results.
Good sound for a driver without being too noisy.
Also, got a little boost in gas mileage.

Cost of repro muffler and tail pipe hangers was a bit much,
so I made my own.
I had some old 4-4-2 hangers that were still in pretty good shape,
so I used them as templates and made new ones.
Used the side wall out of an old tire for the rubber part.
They turned out pretty nice.
You have to look close to see they're not original.
If you're interested I can give you details and pics of how I made them.

 

Thanks for all the feedback. I do have the cap on the passenger side forward opening. I'm going to go stock, no H pipe. I only heard this as single exhaust before so I'll see how it sounds with factory dual exhaust. I can always change things later.

 

Commercial headers for the CS Convertible don't seem available, nor have I found headers that will properly fit. Who ever put them onto my car had to "Massage" the drivers side two front pipes to about 1/2 their diameter to make them fit.

Replaced them with stock cast iron mainfolds, capped off crossover on pass side, and made duals with 2 1/2 dia. Didn't add H or X pipe as I used older
inplace duals and did not add additional piping and costs to the conversion.

Have Flomaster 40's that make nice sound, and are not too loud.

If you're looking for performance from the 330, then you need to get a 455, or LS-X.!
Good luck
Hotrodder.

 

Have Flomaster 40's that make nice sound, and are not too loud.

If you're looking for performance from the 330, then you need to get a 455, or LS-X.!
Good luck
Hotrodder.[/QUOTE]

im sorry, i thought you said LS-X,
shame on you

 

He also said that (no)Flowmasters were not too loud...

 

Your comment about the 330 displays a bit of ignorance I guess you could say.Although we are talking about a 50 year old car the "65 version that was in the Cutlass (and I'm picking through to '67, a bit more) came with 315hp and 360ftibs torques.Pretty good numbers for a mid '60s 5.4litre stock small block that was never marketed as a muscle/pony car or hotrod.
The 330's are also a pretty tough, quality little unit in that they have a forged steel crankshaft as well as forged conrods ex factory, parts that are still sought after today.
Cheers