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MG MGB Technical - 67GT w/74 motor ? exhaust system

I have a 67GT with a 74 18V motor along with the 74 exhaust manifold. I need to replace the entire exhaust system.

Should I be looking for an '74 or '67 exhaust system for this car?
Steve Rechter

Steve,

Do you know if the donor motor had round or rectangular motor mounts? Am sure that the 67 had rectangular motor mounts. Also, does 74 motor have or did it have the same exhaust manifold as your 1967 motor. If it did have the same exhaust manifold, I would think that you can use any MGB exhaust system from 1963 to 1974 prior to MG going to a single Zeinth carb.

HTH

Fred
Fred Wright

The only thing I know about the donor car was that it was a rubber bumper model with the dual SU intake manifold as factory equipped.

My concerns were raised after reading threads in the archive where some were having alignment problems using headpipes from different years.
Steve Rechter

Steve. I am not sure it makes any difference, but I would be inclined to go with the early model (62-67) system myself because you know it will mate up with the various attachment devices under the car.

If you take a look at the two systems, illustrated in several catalogs and on line, you will see that the attachment to the exhaust manifold is the same. The header pipes vary in how they go into the collector (where the two go into one) and then the systems are different in how they are put together. But, I do not see any important differences except for the shape of the middle mufflers--the later model one is flatter and wider which may have been done to give slightly better ground clearance.

But, I would have to question the need for a factory system on anything other than a show car. When I installed the Weber DGV on my 79 roadster, I used an earlier model exhaust manifold, purchased the header pipes (down pipes) for the 68-74 because they had the pipe coming out of the collector, and used the 79 pipes and muffler. The system was assembled by a local exhaust shop (Wade's Discount Muffler) used by most of the mechanics and many of the car dealers in our area.

What I would consider, were I you, would be the use of the later style header pipes into a good muffler with no middle muffler. This is the system I have been using on my 68GT with good success for a number of years. Damaged the middle muffler on too many local speed bumps (set up to slow down pick up trucks and never designed with a low slung car in mind), so I read about removing it and simply running a straight pipe between the header pipes and the rear muffler. That has worked quite well for many years.

As to what muffler to use, talk it over with a good custom exhaust system shop. When I was traveling across the US, back in 81, the rear muffler hanger broke on my 79 MGB. Called the nearest remaining MG dealer, about a hundred miles away. They suggested I go to my nearest Midas muffler shop. Worked out well.

Les
Les Bengtson

With a little bit of research I found the answer to my question in the TRF catalog.

They offer a five piece system for 62-67 and a three piece system that can be used for 62-70. They say that the two systems are interchangeable. (Odd that their five piece system is $30 cheaper than their three piece.)

Les, thanks for the advice. I was thinking along the same lines of eliminating the center muffler. Now that I know that I have an option of which head-pipe to use, I will have to find a suitable rear muffler.
Steve Rechter

On my '67 I originally replaced the exhaust with the stock 5 piece system. When that gave out I went to Midas and purchased the 3 piece system for '68 to '74. This system has the pipes welded to the mufflers and comes with a lifetime warranty. Midas does not like me very much as they replaced it 3 times over the years at no charge. Eventually, I purchased the Falcon big bore exhaust in stainless and this system, now over 15 years old, looks and sounds like brand new. It has no center muffler to foul speed bumps and will last for the life of the car. RAY
RAY

This thread was discussed between 30/08/2009 and 31/08/2009

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