Who makes the closest modern substitute to the Mopar 2660518 muffler?

Gerald Morris

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Noticing how the huge, wonderful old muffler on Gertrude is dented, I think about replacing it. I looked up the number of the original, and found one at Hilltop for an obscene price, as usual with them. I also have seen a number of offerings by Walker which look close to the right proportions. While I CAN certainly take those nice dual pipes I put on Mathilda just a couple summers ago, which were bent for a '67 model, I LIKE the current big muffler and single pipe setup on this car, and its far easier to just replace a muffler than a whole system.

So, do any of you know for sure what would be the closest modern offering to that old muffler? Other aspirants also might benefit from your lore.
 

Justin Plant

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Modern mufflers are typically made from thinner gage steel than old ones. Every little piece is made down to a price. Walker Quiet Flow is close, it's certainly as quiet. The original Quiet flows were packed with fiber glass. No other stock replacement offers this, to my knowledge. AP offer abunch of "universals" the MSL (muffler shop line) start with a 700 in the part number. They'll be close and a great deal cheaper. Walker's "find by dimension" is awesome. AP's sucks. Well, they don't really have one at all. If you give me dimensions I can look in their book at work.
 

Gerald Morris

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Modern mufflers are typically made from thinner gage steel than old ones. Every little piece is made down to a price. Walker Quiet Flow is close, it's certainly as quiet. The original Quiet flows were packed with fiber glass. No other stock replacement offers this, to my knowledge. AP offer abunch of "universals" the MSL (muffler shop line) start with a 700 in the part number. They'll be close and a great deal cheaper. Walker's "find by dimension" is awesome. AP's sucks. Well, they don't really have one at all. If you give me dimensions I can look in their book at work.

I can crawl under Gertrude tomorrow morn and measure. MAYBE, I can even find a reference to the dimensions of the original item. I saw some Quiet Flow mufflers that looked about right, so I'm glad to know that's an after market item that will do. Hell, I'll even go measure the old Sears muffler I pulled off Mathilda when I put the dual pipes on her. I kept that and the Y pipe in case I wanted to run something on a cradle.
 

CBODY67

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Not sure why the issue? A B/RB engined C-body muffler has been a C-body muffler from 1965 to 1973. They are all the same size, single and dual exhaust, except for the 1969 Dodge Polara 440/375 pursuit cars, which used Street Hemi mufflers under them that ONE model year.

Now, although the case size is all the same on the C-body mufflers, except the '69 Polara mentioned above, the pipe sizes can differ a little bit. The '72 Imperial muffler has the largest pipe sizes and reputed to be very similar flow restriction as the Street Hemi muffler.

After I got my '67 Newport 383 in 1981, it had the factory 4bbl with a single exhaust (although similar Plymouths and Dodges all had dual exhausts with the same 383 4bbl engine). Horsepower ratings were the same 325 horsepower for all. So, with a muffler shop muffler and tail pipe, I wanted to put it back correct and ordered up a '72 Imperial y-pipe back system from a Walker dealer. I had the full Walker paper catalog so that project was fully researched before it began.

So the Walker muffler claimed to have some absorbent material in it to keep it from deteriorating internally from moisture, plus having the small condensate drip hole at the rear seam on the bottom of the case. For the tail pipe, it was '72 also, without the resonator.

So as the middle of the body is pretty much all the same, the pipes fit perfectly and the contours were correct too, as expected as Walker is an OEM supplier, or was back then. The end of the y-pipe, at the ball joint connector, was pitted and might not seal well, so I initially got a tube of Walker's "muffler cement" to fill the holes, but it still leaked just a bit. BUT . . . I figured out a way to fix that!

When I was doing this deal, Chevy had started to use a composition exhaust pipe seal at the exhaust manifold-to-exhaust pipe joint. It was basically 1/2 of a doughnut gasket, but with a metal retainer which snapped into the menifold. So, checking the sizes, I found one of those which was just right to adapt the y-pipe size to the intermediate pipe size of the Imperial pipe. Snapped the metal retainer into the y-pipe and the composition material mated perfectly with the intermediate pipe. Only added about 1/3 of an inch to the total assembled length. All was well.

At the rear of the car, the quarter panel bottom on the Fuselage Car is pretty much parallel to the road surface, so the rear pipes follow that orientation, due to having to clear the rear valence panel below the bumper. Whereas on the 'Slabs', the rear quarter panel angles upward a bit to match the level of the rear bumper. Plus, the '67 had a Class I trailer hitch on it which was in the way. So a trip to a muffler shop which could put the rear pipe in a bender and tweak it up about 1.5" was in order. Success!!!! The "sewer pipe" single exhaust system was completed. Using the existing brackets and hangers. And nobody knows what's under there, either!

At this point in time, probably about all that Walker still has available is the muffler and some hangers, I suspect. NAPA also carries Walker Exhaust, even with the Walker numbers on them . . . or used to. So another source of the complete y-pipe back system might need to be investigated, at least for the pipes.

Personally, I like OEM factory-configuratioin exhaust system items that I can install in the driveway (or in my shadetree shop) with the car safely on jackstands. Seems like everytime I tried to use a quality muffler shop for something, I always ended up getting the OEM stuff to replace it, fwiw. Pipe bends that hit something, quality of the pipes' metal, or whatever. OEM was just better, back then. And to me, that meant Walker Exhaust. But in our present world, I might need to diversify a bit.

Seems like the Formals have used a similar-sized muffler case, but with a notch larger pipe sizes? But in the same inlet/outlet configuration.

Just my experiences,
CBODY67
 
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Gerald Morris

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Not sure why the issue? A B/RB engined C-body muffler has been a C-body muffler from 1965 to 1973. They are all the same size, single and dual exhaust, except for the 1969 Dodge Polara 440/375 pursuit cars, which used Street Hemi mufflers under them that ONE model year.

Now, although the case size is all the same on the C-body mufflers, except the '69 Polara mentioned above, the pipe sizes can differ a little bit. The '72 Imperial muffler has the largest pipe sizes and reputed to be very similar flow restriction as the Street Hemi muffler.

After I got my '67 Newport 383 in 1981, it had the factory 4bbl with a single exhaust (although similar Plymouths and Dodges all had dual exhausts with the same 383 4bbl engine). Horsepower ratings were the same 325 horsepower for all. So, with a muffler shop muffler and tail pipe, I wanted to put it back correct and ordered up a '72 Imperial y-pipe back system from a Walker dealer. I had the full Walker paper catalog so that project was fully researched before it began.

So the Walker muffler claimed to have some absorbent material in it to keep it from deteriorating internally from moisture, plus having the small condensate drip hole at the rear seam on the bottom of the case. For the tail pipe, it was '72 also, without the resonator.

So as the middle of the body is pretty much all the same, the pipes fit perfectly and the contours were correct too, as expected as Walker is an OEM supplier, or was back then. The end of the y-pipe, at the ball joint connector, was pitted and might not seal well, so I initially got a tube of Walker's "muffler cement" to fill the holes, but it still leaked just a bit. BUT . . . I figured out a way to fix that!

When I was doing this deal, Chevy had started to use a composition exhaust pipe seal at the exhaust manifold-to-exhaust pipe joint. It was basically 1/2 of a doughnut gasket, but with a metal retainer which snapped into the menifold. So, checking the sizes, I found one of those which was just right to adapt the y-pipe size to the intermediate pipe size of the Imperial pipe. Snapped the metal retainer into the y-pipe and the composition material mated perfectly with the intermediate pipe. Only added about 1/3 of an inch to the total assembled length. All was well.

At the rear of the car, the quarter panel bottom on the Fuselage Car is pretty much parallel to the road surface, so the rear pipes follow that orientation, due to having to clear the rear valence panel below the bumper. Whereas on the 'Slabs', the rear quarter panel angles upward a bit to match the level of the rear bumper. Plus, the '67 had a Class I trailer hitch on it which was in the way. So a trip to a muffler shop which could put the rear pipe in a bender and tweak it up about 1.5" was in order. Success!!!! The "sewer pipe" single exhaust system was completed. Using the existing brackets and hangers. And nobody knows what's under there, either!

At this point in time, probably about all that Walker still has available is the muffler and some hangers, I suspect. NAPA also carries Walker Exhaust, even with the Walker numbers on them . . . or used to. So another source of the complete y-pipe back system might need to be investigated, at least for the pipes.

Personally, I like OEM factory-configuratioin exhaust system items that I can install in the driveway (or in my shadetree shop) with the car safely on jackstands. Seems like everytime I tried to use a quality muffler shop for something, I always ended up getting the OEM stuff to replace it, fwiw. Pipe bends that hit something, quality of the pipes' metal, or whatever. OEM was just better, back then. And to me, that meant Walker Exhaust. But in our present world, I might need to diversify a bit.

Seems like the Formals have used a similar-sized muffler case, but with a notch larger pipe sizes? But in the same inlet/outlet configuration.

Just my experiences,
CBODY67

Your taste in workplaces runs the same as mine, which is why I'm looking at Walker's stuff. I'll just crawl under Gertrude tomorrow morn, before the blast furnace heat of the day, and measure the muffler. I'm NOT paying Hilltop their outrageous price for that NOS piece they have. I don't mind a reasonable fee for a good muffler, to be sure, but I'm not looking at anything for shows or collectors. I just want to keep it quiet when the current muffler erodes. That hopefully won't happen soon.
 

detmatt

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There’s a couple of places here in Michigan that have inventories of NORS exhaust parts including mufflers. I just bought the correct replacement single for the Mobile Director a couple of months back.
 

73Coupe

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Waldron's offers reproductions as close to original as you'll get. Insulated too.

Walkers are non insulated.

I did a trial and error on my dual system with a few different mufflers (documented in a thread here somewhere).
 

Gerald Morris

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There’s a couple of places here in Michigan that have inventories of NORS exhaust parts including mufflers. I just bought the correct replacement single for the Mobile Director a couple of months back.

I'll direct my searches to emphasize Michigan. I need to crawl under Trudi and measure what's there. I now suspect the military mechs who clearly wrenched on her for some decades put a larger than standard muffler on, if indeed the C body standard is what I have on my dual pipes. Those work fine enough, but THIS arrangement is so quiet that the gal at Emissions asked me if I had the motor running when she approached to check her. BTW, that old motor PASSED EMISSIONS ON THE FIRST PASS, WITHOUT ME TUNING IT UP AND AFTER HAVING RUN IT SINCE MARCH!! The HC count was higher than MY liking, ~310 ppm, w the State limit at 500, but HEY! it was good enough, with the remnants of those 516 heads and the warmed over Stromberg carb and bad lifters and valves all.

This buys me TIME, to now get ANOTHER ENGINE READY instead of having to do a valve job on this one in situ, a prospect I don't care for.

NOW, I can start with a vatted, clean BLOCK, and BUILD an engine, new rotating assembly et al!

I'm looking to Hughes for a nice cam/lifter combo. Do you think that's wise, or too conservative? Some suggest that modern grinds offer better performance for the modern CRAPOLINE we're forced to run. I'll start a thread on this later....
 

Gerald Morris

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Waldron's offers reproductions as close to original as you'll get. Insulated too.

Walkers are non insulated.

I did a trial and error on my dual system with a few different mufflers (documented in a thread here somewhere).

Yes, and I may well use Waldron. This is as easy as exhaust jobs get. So long as the old muffler remains intact, I'm VERY pleased with it, but curious. I've never driven a quieter vehicle.
 
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