Exhaust System Resonators

Robert Shepard

Robert Shepard

Website Administrator / Past President - Golden St
The resonator that was once on my Criterion is long gone. Due, no doubt, to the exhaust system being replaced more than once before I purchased it. Wanting to keep my car correct and Cadillac quiet, I checked USA Parts Supply for a replacement unit, and found that the one they list excludes the commercial chassis. I was wondering if any of your professional cars still retain their resonators, or if you have fond a replacement source for them. I do know the trade off for keeping the exhaust quiet is back pressure, resulting in less power.

While my 1975 Criterion lacks an exhaust resonator, it does have one attached to the air intake that is connected to the air cleaner. There are baffles in it, so I would think it is there for noise suppression.
 
resonator

Are you SURE that is a resonator attached to your air intake?
I found a resonator on that famous (or imfamous) auction site. It was put on my 61 MM when they replaced the rest of the exhuast system. The muffler shop did not have a listing for a resonator for my car. Now if I can just figure out why the exhaust gaskets keep burning out too soon my car will be quiet.
The big Hershey auto show and swap meet is in a couple weeks. Maybe I should look for more resonators. Since so many cars were built without resonators and they were quiet maybe there is something else the resonator is good for too. Any thoughts on this Paul?
Mike
 
The resonator serves more of a purpose than that of noise suppression. It also puts in some restriction to the breathing of the engine. Many people believe that the less back pressure in the exhaust system, the better the car will run. The engine needs some back pressure to keep the cold air from getting back into the system. With long exhaust systems this isn't as much of a problem, however, with a short exhaust system, the "cooler" air that is drawn back into the engine can cause valve problems. This is often seen with engines that run straight exhaust pipes of a larger diameter. To prove this "theory" put a piece of paper near the end of the tail pipe and you will notice that it is occasionally sucked toward the exhaust pipe.
My thoughts are that the parts books leave a lot to be desired when it comes to exhaust systems. My 1978 commercial chassis still has the original exhaust system on it from new. I know this because of the fact that it isn't clamped, but welded into one piece. It also has the original GM markings on the muffler. This car doesn't have a catalytic converter installed, and it does have a resonator. The parts book shows a cat in the system, but it doesn't relate to what was originally installed. Possibly since my car was originally delivered to Canada, the cat wasn't required? I just don't know, and I have researched this as best as I could. GM was known for making running changes in installed equipment, and there is no documentation on these changes that I know of. You just have to go with what you think is correct and live with it.
My 1963 Chrysler originally came with a resonator on a single exhaust system, but when I had the exhaust done, they didn't install a resonator. Decided that it could be done later on if the car was too noisy, however it isn't. This car showed remnants of having a dual exhaust system originally, and that was converted to a single exhaust at some time in its life. Only thing that I can think of was that the fire department wanted to save money when it was replaced.
 
Mike Stevens said:
Are you SURE that is a resonator attached to your air intake?
I found a resonator on that famous (or imfamous) auction site. It was put on my 61 MM when they replaced the rest of the exhuast system. The muffler shop did not have a listing for a resonator for my car. Now if I can just figure out why the exhaust gaskets keep burning out too soon my car will be quiet.
The big Hershey auto show and swap meet is in a couple weeks. Maybe I should look for more resonators. Since so many cars were built without resonators and they were quiet maybe there is something else the resonator is good for too. Any thoughts on this Paul?
Mike
Click to expand...

The air intake resonator was standard for my model year. I have attached a eBay auction that shows it attached to the air cleaner housing.

http://cgi.ebay.com/Cadillac-DeVill...ucks?hash=item4ceb1fa64c&_trksid=p3286.c0.m14
 
they could call it a resonator but it's a baffle to me. I do think it was set for a flame retarder in case of a back fire. the 75 is the only year I have see them on. of course that makes them even harder to find. the resonator on the tail pipe was to smooth out the noise. add it and the converter and the car was vary quit.
 
Resonator

My 74 M&M had one until a couple of years ago when it fell off while camping:( Go figure. It hasn't been replaced yet. It's on that ever expanding to do list.:eek: The car had 58K miles on it when I got it and it seemed original.:)
 
Scott Avnaim said:
My 74 M&M had one until a couple of years ago when it fell off while camping:( Go figure. It hasn't been replaced yet. It's on that ever expanding to do list.:eek: The car had 58K miles on it when I got it and it seemed original.:)
Click to expand...

Let's go Scott, get that thing ready for Albany! :thumbsup:
 
Paul Steinberg said:
What you have pictured in the auctions is air cleaner muffler. I haven't had the time to look up the exact terminology that GM used to describe this item, however, generally speaking a resonator comes after the muffler.
Click to expand...

My GM factory manuals list it as a resonator. I'm not sure what its function is, or how it works since it is on the intake side. There are baffles in it though.
 
Robert Shepard said:
The resonator that was once on my Criterion is long gone. Due, no doubt, to the exhaust system being replaced more than once before I purchased it. Wanting to keep my car correct and Cadillac quiet, I checked USA Parts Supply for a replacement unit, and found that the one they list excludes the commercial chassis. I was wondering if any of your professional cars still retain their resonators, or if you have fond a replacement source for them. I do know the trade off for keeping the exhaust quiet is back pressure, resulting in less power.

While my 1975 Criterion lacks an exhaust resonator, it does have one attached to the air intake that is connected to the air cleaner. There are baffles in it, so I would think it is there for noise suppression.
Click to expand...

If you locate an air intake resonator, I want one Robert. I just replaced the entire exhaust system on my Criterion thinking about duals. But, turns out I cannot do duals because the gas tank is off-set. I did not install the resonater either and it is quiet. Instead of running the tailpipe straight out the back we actually turned it a bit and looks great!
 
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