RQ B 2426 1976

[Tony S]

Hi, I am new to he forum and just become the owner of RQB 2464 which is in pretty good mostly original shape with the exception of a few minor and one major item. The car needs hog troughs but I will address that at a latter date. My current focus is the left side engine pipe that comes down next to the steering drag link. The pipe has been smashed almost flat to allow the steering arm to make a full swing. the pipe is at the end of the travel of the arm. Is this normal? Could the wrong manifold be on the engine. Is the pipe wrong? The car still has the cat and fake dual exhaust. I am thinking of doing a true full exhaust but if the d/s pipe has to be smashed to fit I guess there would be no benefit to true duals.

[Jim78]

Hi, I am new to he forum and just become the owner of RQB 2464 which is in pretty good mostly original shape with the exception of a few minor and one major item. The car needs hog troughs but I will address that at a latter date. My current focus is the left side engine pipe that comes down next to the steering drag link. The pipe has been smashed almost flat to allow the steering arm to make a full swing. the pipe is at the end of the travel of the arm. Is this normal? Could the wrong manifold be on the engine. Is the pipe wrong? The car still has the cat and fake dual exhaust. I am thinking of doing a true full exhaust but if the d/s pipe has to be smashed to fit I guess there would be no benefit to true duals.

Believe it or not, that ugly pipe is from the factory. Like you, I couldn't believe that they would restrict the pipe that badly. Last year, I converted my '78 to straight duals. I installed stainless pipes that I purchased from Don Simmons (Silvertone Exhaust Systems, 519-485-1966). He had not done a system specifically for replacement of a catalytic equipped car. I used pipes from the system that he sells for 65-74 Avanti II. The d/s downpipe is shaped in such a manner that it is not crushed like your original.

The important consideration is which of two possible manifolds types you have on the engine. Don can give you specifics on what to measure to determine the type that you have. IIRC, it is the distance from the outlet flange up to the centerline of the bolts that attach the manifold to the block. There are two pieces to each exhaust pipe, and two pieces to each tailpipe. On my Avanti, I found that the rear part of the tailpipes (over the axle) were the same as the originals, so I didn't need to replace them. I used Thrush round glass-packs for the mufflers. There is some tricky alignment getting that many components turned and twisted to snake through the frame without something touching. I would not recommend attempting the job without the benefit of a lift. Don can also supply new hangers and very nice HD stainless clamps. I would recommend buying them.

[Avanti83]

Hi, I am new to he forum and just become the owner of RQB 2464 which is in pretty good mostly original shape with the exception of a few minor and one major item. The car needs hog troughs but I will address that at a latter date. My current focus is the left side engine pipe that comes down next to the steering drag link. The pipe has been smashed almost flat to allow the steering arm to make a full swing. the pipe is at the end of the travel of the arm. Is this normal? Could the wrong manifold be on the engine. Is the pipe wrong? The car still has the cat and fake dual exhaust. I am thinking of doing a true full exhaust but if the d/s pipe has to be smashed to fit I guess there would be no benefit to true duals.

Tony

Jim has pretty much covered the options. My 83 RQB3156 has a Simmons 2 1/4" SS exhaust system mated to 2 1/2" SBC manifolds. I highly recommend the system and I purchased the hangers and clamps with the system. Not only is the quality good but Don's prices are also reasonable. I put mine on with the car on jackstands but a lift, Which I now own, would have made it much easier.

I didn't keep the converter and went with the dual system that fits the earlier non-convertor cars.

Remember, there is little if any difference in engines and frames from 66-84. I know the cubic inches changed but blocks is blocks with SBC's

Here's a shot of the exhaust pipe you mentioned and if you would need further shots, here's my post from the SDC Forum. http://forum.studeba...picture-warning

I've got around 75 shots if you need further info.

Bob

[Tony S]

Thanks guys. You have answered my question. This is my second Avanti ll. I owned one about 12 years ago and the only thing I can remember is that it had a 350 chevy motor in it. I don't recall the pipe being bashed up on the d/s like this one. I will call Silverstone next week and explore my options. I am lucky enough to have my own lift and complete shop so I will also try and salvage the back half of the system and use earlier engine pipes for a true dual system. The first thing I am going to have to do is replace the 6 manifold studs.

[Jim78]

I will also try and salvage the back half of the system and use earlier engine pipes for a true dual system.

I thought that I might have been able to salvage the stainless mufflers. I found that the ovals were not a good fit when mounted forward in the "X" of the frame. The rear sections of the tailpipes were the only items that I was able to salvage.

The straight system has the downpipe, downpipe to muffler, muffler, muffler to tailpipe, tailpipe, exhaust extension on each side. On my '63 Avanti, there was an "equalizer" pipe between the two pipes in front of the mufflers. I haven't seen this "H" pipe arrangement in decades. I guess that the flow improvement didn't justify the cost.

[Tony S]

Well I figured I would try and tighten up what I thought was a loose flange on the p/s exhaust manifold. After breaking the first stud I used heat on the flange and the other 2 came out easy. I pulled the pipe down and tried to slide out the heat riser to change the gasket. That went well except the bottom half of the manifold fell out with it. It seams that the bottom collector of thr manifold had broken clean off. What was really unusual was the cast iron looked like it had become crystalized like little sugar cubes. I have never seen anything like it. I did some research on the GM part number and it seems this is a common manifold used mainly on 350 corvettes between 1969 to 1974. It is actually stocked by Autozone as a Dorman replacement part and I will have it tomorrow. The only difference is it looks lioke it has the egr ports that will need to be plugged.