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GM B-Body Forum, 77-79 Caprice/Impala Forum

A forum for all the owners and enthusiasts of General Motors B-Bodies from 1965-1996, but dedicated to the owners of 1977-1979 Impalas and Caprices. Join up now!

    dual exhaust for an olds B


    Posts : 1
    Join date : 2018-06-04
    Age : 55
    Location : I moved to Pittsburgh to be closer to Primantis

    dual exhaust for an olds B Empty dual exhaust for an olds B

    Post  quaddriver on Mon Jun 04, 2018 11:38 pm

    I have a 78 98 with the 403., just changed my registration to antique, now I can do whatever I want to it and the state cant say boo. I want to do duals as the stock 403 gains 20-25hp just letting it breath thru 2 pipes. already did a cop bar on the rear, found a set of year correct rallys, rebuilt the 400 to handle whatever I end up doing to the 403...

    however, its no longer the 80's and parts for this just aint around. Its been in fact 18 years since I restored/modified my last set of full size wagons and parts were getting hard then...

    I need essentially muffler mounts and both tailpipes, the I-pipe and the pipes off the manifolds I can handle. the crossmember I can weld creatively (I see from some photos someone makes a section you can weld in after a few cuts?

    any chance any old 77-80-something cop stuff is still around?

    there are still a couple shops around and if I could get a bend card for the pipes (I know, Im dating myself...)

    Guy Newport

    Posts : 2
    Join date : 2017-07-13

    dual exhaust for an olds B Empty Some Observations on B-Body Exhaust Solutions

    Post  Guy Newport on Sun Jun 24, 2018 11:08 am

    You might want to take a look at a Walker Muffler catalog for the exhaust parts you need in carbon steel. There's many similarities between years and B-Body makes. What might flummox you is what's not pictured: the heat shields and cross member configurations. If you look at a sedan cross member, you'll notice it's curved upward on the pass. side in order to clear the exhaust and straight on the driver's side. If you take two crossmembers, you can cut the pass. side off one and the driver's side on another to make a single crossmember with two humps in it. You just need to cut your first crossmember off so you keep the trans mount; GM mounted cross members straight across the body as well as at an angle. Depending on your body style, you may also need to push the floor pan upward to clear the new hump on the driver's side. What the heck, it'll be on the rear passenger's side behind the driver, LOL. Grab the heat shields from the car you got the cross member from, flip 'em over and use 'em on the driver's side. This works for sedans; SW are more complicated 'cause the internal spare storage moves the fuel tank over toward the driver's side (as well as being bigger than a sedan). The easy solution for them is to exit the exhaust in front of the rear wheels. For them you could get a later Roadmaster tank with it's center fill and door.....but that's an entirely different problem than the one you're trying to address...One more thing: if you're replacing a muffler on a B-Body SW, don't bother especially if you're retaining the resonator at the end of the pipe. The stock diameter of pipe plus the length of it is of sufficient to quell the noise of the exhaust to a "just right" level in and out of the vehicle. I've done this with pre and post '90 body styles and it works just fine; no, I don't have profound hearing loss, and neither does She Who Must Be Obeyed (Rumpole of the Bailey reference). Just have a shop bend you up a short offset pipe replacing the muffler (you're duplicating it's offset with the pipe) and try it out. You'll be pleasantly surprised; I certainly was when I did it.

    Last edited by Guy Newport on Sun Jun 24, 2018 11:17 am; edited 1 time in total (Reason for editing : One more thing....)

      Current date/time is Wed Jul 08, 2020 10:30 pm