Proper routing of rear exhaust of 71-76 GM full-size wagon

In Canada, single exhaust was all that was available on the B and C body G.M. cars, right through until the Wales came out. Even on cars that looked like dual, it was a single through the middle with two outlets from the muffler, as there was only a single catalytic converter installed. The transmission cross member was not notched for the second pipe, either, so adding duals properly can be a bit difficult.

 

That's when you get the older crossmember

 

100% sure the pipe went under the axle because I had one, first thing I replaced with headers and dual exhaust and modified crossmember.
The guys who fitted the new pipes just made sure these were not "straight" pipes but curved it just a little more under the axle so I had more space.

 

Late to the party again, but I also remember it being under, and exhausting out to the left. When my son's '72 Kingswood Estate needed the Tail Pipes replaced, I called my local parts store and could not believe the price on it, even at my discount.

So I called one of the Muffler Shops that does custom work and he gave me a price of about $22 over the phone. Well, I could not get there quick enough. Once he saw it though, he backed out of our deal, saying that he did not realize it was like that on those cars, but agreed to do it if it exhausted to the right. It was not correct, but for an old driver, I agreed. It did pass inspection and served it's purpose, although on a nice Classic, I would have to have it correct.

WagonKiller, great Illustrations above.

Bill

 

Actualy those are ChevyGod's Illustrations

 

A little late to the party, but here's some more pictures regarding dual exhaust:


Factory apparently cancelled the dual exhaust option in 1974 per the GM drawings.






Routes under the axle, there's just no room to fit it above the axle.




Exits left side, wheel well on the right side is in the way.

I had a shop custom make me a true dual 2.5" exhaust with Dynomax mufflers. Nice and quiet and flows well.

 

Thanks for the replies. Sorry just now getting back to this.

Well it obvious that they didn't bend the pipe enough and now that I think, on their lift, they lift the car with the tires and my mechanic lifts the car by the frame and the tires hang down. That explains why where was the clearance when it was at the muffler shop.

Anyway my dad took his Toyota truck to that muffler shop today to have some repairs made and my dad told the owner about my car. This was before I had told my dad I had got info here and it was properly routed, but wasn't bent properly. Well he said the owner said it was run right and there wasn't enough room to run it above. I asked him if he told him that brace had broke and he said yes and then I asked him what he said then and he said he just walked off. Oh well.

Still they didn't bend the pipe correctly and the bracket broke and they need to fix it. Hopefully I can get it out there next week.

Thanks!

 

That looks really nice!

Just noticed, is this an optical illusion or what do you have in the tailgate, how did you fit that in there?

 

That is an engine in the back. Carb to pan 1972 Pontiac 400 v8. I use my wagons for work! With the right tools and careful positioning you can fit a full engine in the back of a GM clamshell.

 

I also use mine for work/towing

 

These cars are a tough as a pick-up !!

I used to use my son's car for some misc hauling as well.

Bill

 

Here's a photo of the underside of my recently-sold '73 Custom Cruiser. The exhaust pipe goes under the rear axle. The '73 Olds Chassis Service Manual shows it running under the axle. My car appears to be missing the resonator. Never noticed that before.






Note the section in the middle of the page labeled "Exhaust System Station Wagon."

 

I have NEVER seen a resonator on any of them

 

My '74 had a muffler and resonator on it just like the factory drawings showed it was supposed to (GM part numbers on them).

 

I think that possibly it depended on which engine you got whether there was a resonator or not. From the factory, most Oldsmobile V-8s did get one, but most Buick engines did not. All in tuning the exhaust sound for the car, I guess. The Buick engine has a more mellow tone without the resonator being needed.