Side pipes

[Roger A Clark (12557)]

I have a 65 roadster that I purchased 16 years ago, which at the time had 2 1/2" side pipes with a crossover pipe connecting them (in front of the oil pan). With the exception of the crossover pipe, they appear to be original pipes. Soon after purchasing the car, I ordered a new set of side pipes from a well-known Corvette supplier. When they came, they were labeled as GM OEM with the correct part numbers. The left side pipe fit perfectly but the right almost hit the frame on the outboard front. In viewing the pipe from the rear, the left side pipe is parallel to the frame whereas the right pipe is not parallel to the frame (it is about one inch from the frame in the rear where it attaches to the frame, but almost hits the frame in the front, just before it makes a 90 degree bend toward the engine). The pipe also hits the frame where it crosses underneath. (Note: The 327 engine is the original with the correct exhaust manifolds.) The frame has never been damaged or altered. Functionally, it would work, but I do not believe this was the way GM built them. I have sent the pipe back to the supplier twice now and they have sent me replacements; all of which have the same problem. I'm sure it has nothing to do with my car in that I had this same problem 16 years ago when I tried to replace my “under the car exhaust system” with OEM side pipes which I bought directly from GM. Also of note- the pipes that originally came with the car fit perfectly and both of pipes are perfectly parallel to the frame. Clearly, the newer right-side “GM” pipes are different than the originals.

Is there something I'm doing wrong, or has GM changed the way they make the pipe?

[Wayne Midkiff (3437)]

Is the Heat-Riser Valve in place ? *NM*

[Roger A Clark (12557)]

Re: Is the Heat-Riser Valve in place ?

Sorry, forgot to mention that my car is a fuel car which does have a spacer between the manifold and the pipe (which is on my car) but no mechanical riser (flap) as on non-fuel cars. Thanks anyhow. Any other ideas?

[Wayne Kindschy (33314)]

Re: Side pipes

Is the motor mount different on that side?

[Roger A Clark (12557)]

Re: Side pipes

I have replaced the motor mounts with the correct (nonlocking) type that came with the car from the factory.
Pls let me restate the problem. It is not the car or engine because the original pipes fit perfectly and when compared to the new pipes are of different length. In other words, the manufacture of the pipes changed the blue print or the jig. What I'm really looking for is if others have experienced this problem. I think the problem is in the pipe (right side only) itself.

[Wayne Kindschy (33314)]

Re: Side pipes

Roger,

My 67 was a under the body exhaust system which I changed to GM side pipes in 1997. All parts were ordered from Corvette Pacifica at that time and everyting was changed over without any problems. The parts were drop shipped to me and I don't remember where they came from.

[Jack Humphrey (17100)]

I'm scratchin' my head....

Sounds like the common problem of pipe cant.... This is an installer issue.

Side pipes mount at a single point in the rear to the frame side rail and to the exhaust mani via three studs/bolts. In geometry, three points determine a plane. So, if you don't follow the book when attaching the pipe, you can easily cant it up OR down by several inches with respect to the forward end of the frame side rail....

The right mounting proceedure is:

(1) Loosely insert rear of pipe in frame side rail cutout.

(2) Start forward end of pipe onto exhaust manifold studs and install nuts 1-2 threads ONLY.

(3) Place a support under the front of the side pipe to make it run level along the frame rail from front to back with the same clearance all the way.

(4) NOW, begin the final torque of the exhaust manifold stud nuts and pull 'er into place letting the exhaust donut swivel, lock and hold the desired final rest position.

If you didn't do the installation in this fashion, you didn't get the appropriate final resting point PLANE at the end of the exhaust manifold and have the wrong forward pipe cant. Kiss the existing exhaust donut bye bye, buy a replacement and do 'er again....