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muffler size for '74 eldo

Started by Viator Trudeau, August 23, 2015, 10:26:48 PM

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Viator Trudeau

Are stock mufflers big enough for the 500 CI eldo engine's.   The muffler on my eldo from a regular muffler shop seem too small for a 500 cubic in engine.  Looking around at mufflers from the sources in Hemming  (  24" long and 6 x 12 ovals) do not seem big enough for the large motors.
Any comments from the field??

V. Trudeau

Scot Minesinger

I believe Classic Auto exhaust and Walker both sell a correct muffler for the 472/500 engines.  Classic Auto Exhaust as I remember used to sponsor this forum.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

76eldo

I bought a muffler from them for my 76 which now has a 71-74 full system and the Walker muffler installed perfectly in between NOS pipes.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

TJ Hopland

The stock mufflers on these didn't look much different than other V8 mufflers of the era.   If you went to a 4 or 6 cylinder car you got one a little smaller but overall they were all similar in size, it didn't seem to matter if you had a 260 or a 500.

Unless you are planning or have made other modifications to the engine I don't think the stock muffler is really causing any issues.  If you are running stock air cleaner just go look at the size of the inlet on that, you will no longer thing a 2 1/4" (or what ever it was) muffler is going to slow things down with that in the system.   

If you really want something bigger have a look at a place like summit where you can search mufflers my inlet and outlet size.   They have a wide range starting at 1" going all the way to 6".   4" is real common on diesels and you can go bigger if you want.  Bigger inlets generally mean an overall bigger case which takes up more space which is already kinda tight under there.   Its also been my experience that the bigger the pipes are the harder it is to keep em quiet and keep the system from having a drone at certain RPM's.   IF that is what you are into fine but its really annoying if you like quiet.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

"Cadillac Kid" Greg Surfas 15364

Viator,
The exhaust system of your Eldo was designed to silence the noise while simultaneously eliminating any excessive back pressure that would lead to power reduction.  The mufflers consist of a baffled primary muffler and a straight through "resonator" at the rear to help tune the exhaust note. The factory system will more than handle the 700 or so CFM the engine will generate.
That said if you are going to replace your muffler be sure that the replacement muffler has an inlet and outlet the same size as the original pipes, and the resonator again is full size.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-