I'm confused by the info I read and hear about oversized factory exhaust systems.

The old Mopar engine manual says the Dart Light and Feather Duster had a "large" manifold to converter pipe, and those are the only models referrenced. It does not say what size this large pipe is.

I've read in several posts that the Super Six also had a larger pipe, and the dimension often quoted is 2.25".

I removed the pipe from my '79 Aspen Super Six and measured the exit diameter of the manifold to be 2.0". The inside diameter of the factory exhaust pipe measures 1.7". My '64 Valiant measures exactly the same.

It seems logical that there would be a substantial improvement in exhaust flow if the pipe was even as big as the manifold.

Has anyone else done these measurements? Is there a factory pipe for early A-bodies with a 2" ID?

lancer_41@excite.com

I have measured many SL6 exhaust manifolds and they are all 2 inch outlets. Even the Hyper-Pak cast iron exhaust manifolds have 2 inch outlets.

You are right about increasing the pipe diameter, that helps a lot, even if you just go 3 or 4 feet with 2 - 2 1/4 then back down to the smaller stock size.

As for an early A-Body 2 inch header pipe, they never offered one from the factory. (I do have a "template" and the bending program for one but I don't have the pipe bending equipment : - (

It's funny how the manual places a large emphasis on the Feather Duster system...
All the system is (I have two complete stock sets...): 2" ID header pipe with adjustable flanges from the exhaust manifold to the Cat Converter, then the Cat Converter, 2" ID pipe to the muffler, the muffler, then 1 3/4" ID pipe exits the muffler makes a "u" over the rear axle and exits below the rear bumper...

I'd personally like to try a 2" system the whole way without the cat (my state's emission laws won't let me though....)

hope that helps,

-D.Idiot

Glad to hear my parts are normal.

I have a muffler guy who is pretty talented at bending tubing, so I think I'm going with a 2" pipe to the muffler.

What do you suggest for a header flange?...grind out the stock part to accept the larger pipe, or buy a 2" universal fit from a place like JC Whitney?



lancer_41@excite.com

I bet your Exhaust Guy has a flange he can use or machine-out one of the thick factory ones, either way works.
DD

This is only one of the many errors in that book. Other books have other errors. Save 'em all, collect the whole set!

The Feather Duster/Dart Lite system was nothing more than a 318 exhaust system. 2" headpipe, 2 1/4" off the catalytic converter, 1 7/8" tailpipe.
:
: I've read in several posts that the Super Six
: also had a larger pipe, and the dimension
: often quoted is 2.25".

That is correct. And I have a tech bulletin stating that all slant-6s got the 2 1/4" headpipe for midyear '76.
:
: measured the exit diameter of the
: manifold to be 2.0".

Yep. That's what size they are. If the casting's good you can bore 'em to 2 1/8" with a cylinder hone and a lot of patience.
:
: The inside
: diameter of the factory exhaust pipe
: measures 1.7".

Well, 1 7/8", but who's counting? It's too small.
:
: It seems logical that there would be a
: substantial improvement in exhaust flow if
: the pipe was even as big as the manifold.

2 1/4" headpipe. If it can be bent to fit my '62 Lancer, it can sure as heck be bent to fit your Aspen! All of this is a bend-to-order deal, you won't be ordering these pipes pre-bent off the shelf.

And by the way, despite "common knowledge", properly-designed and sized catalytic converters are considerably LESS restrictive than most on-street mufflers. The way to minimize catcon restriction is to use a catcon with a LARGE inlet and a LARGE outlet. 2 1/2" and 3" units are available, intended for pickup trucks, and this is the kind you should insist on. Use a step-up adaptor to go from your 2 1/4" headpipe to the catcon. Try to have at least a foot of 2 1/2" or 3" pipe off the catcon before stepping back down to the 2 1/4" inlet of your muffler. A 2" tailpipe is fine.

--DS

redbear@vrx.net