Mufflers…again

[Mach1 Driver 560]

In a recent post “Trunk wiring routing” some very interesting facts about dual mufflers were discussed, most of which were new to me because my 69 Mach1 has one big honking original single muffler. Yes it still has the Ford logo, and all the associated parts. I will be changing to dual exhaust so I'm always interested in knowing the changes between the two.

In the trunk wiring thread “stangs-R-me” brought up the fact that the 70s had some dual mufflers in front of the axle, while the 69s only had them transversely mounted. Since the transverse muffler is mounted on its side between the pumpkin and the fuel tank, it has special wiring to keep it clear of hot exhaust parts.

Problem ONE is that I want a quiet car in which my wife will want to go for a drive and in which we can have a discussion without yelling, enjoy the radio, etc.

Problem TWO is that I probably will switch to EFI and my current best fuel pump option is a Holley 12-305. This is an in tank pump and regulator that has no need for a return line and also has a hydromat and fuel sensor that all fits neatly into a stock tank. It’s down side is that it has four wires going into it instead of one, and the fuel inlet seems to stick up slightly more than the stock one, which could make it problematic with a transverse muffler right next to it. So why not avoid the potential issues and change to 70 style dual mufflers in front of the axle?

I have both 69 and 70 Part and Body Illustration Manuals and they show the part numbers, but I could find no on-line reference to the DOZZ-5230-E&F, D&B, J&C, OR G&H mufflers so it isn't possible to find pipe and muffler size. I think the challenge in using a 70 system is finding one that is close to authentic. Everyone that makes a muffler has a system and they are all probably too loud.

So my first question is for RPM- Bob you used a Walker Quiet Flow 21856 which is 19 x 4-1/4 x 9-3/4 with 2-1/2 pipes (edit, make that 23 instead of 19). I know you have side exit exhausts, but do you know whose pipes would position that muffler in the stock brackets, then exit up over the axle and out the back?

Anyone else have suggestions? We are talking quite here guys, not Magnaflows.

[RPM 1,190]

I believe the Mustang Steve group guys who have the Walkers out the back have one off muffler shop pipes. The  21856 is a really tight fit, requiring cutting an inch of the rear outlet, and immediately 90° up and over the axle.

I do know Walker makes a shorter version, but don't know the model number. Bullet Bob on the MS site has the shorter version, I'll get that for you on Monday. 

 

[Boss429Dreamer 18]

Driver, you are the original owner, why not leave it original? Forget all those high$ mods. My car had the exhaust system you are talking about getting when I bought it. Pulled it all out and put in an original (repop) system with the transverse muffler and now it's nice and quiet, compared to what it was. Just my opinion.

[RPM 1,190]

Terry,  the part number of the short Quiet Flows are #22430. And his are for 2 inch tubing, he doesn't know if the shorts are offered in other sizes. Doesn't really matter as the Walkers neck down inside to 1⅝ inch. I've heard the exhaust on Mustangs with both long and short Walkers and couldn't hear any difference. 

 

[Mach1 Driver 560]

Thanks guys, it was "decision tree" time so I could get a clear direction of how I wanted to build the car. One thing influences another, and so on.

EFI won out slightly over a carburetor

A transverse muffler won out over individual dual mufflers, because it is quieter

A stock fuel tank and Holley 12-305 return-less pump is OUT because the EFI can't handle the heat from a transverse muffler affecting fuel temperature

A Holley Sniper EFI Conversion Fuel Tank is IN because it allows the use of EFI and a transverse muffler.

Now if I don't change my mind....

 

[RPM 1,190]

Just to confirm our agreement of you not painting the car, right?

[Mach1 Driver 560]

13 hours ago, RPM said:

Just to confirm our agreement of you not painting the car, right?

Ha, I am so over that color- its gotta go

[Mike65 476]

Terry I am going to use a dual exhaust system with dual mufflers in front of the rear axle that I bought from Virginia Mustang that has turbo mufflers & has the mounting brackets welded in the proper place for stock hangers. Here is the link to the system I have. It says on the muffler Xcelerator turbo muffler & the body of the muffler is 14" long.

67-69 2 1/2" TURBO DUAL EXHAUST SYSTEM WORKS WITH ORIGINAL STYLE 67-69 HANGER KIT TRIM TAIL PIPES OR USE OUR TURNDOWNS (virginiaclassicmustang.com)

[Mach1 Driver 560]

2 hours ago, Mike65 said:

Terry I am going to use a dual exhaust system with dual mufflers in front of the rear axle that I bought from Virginia Mustang that has turbo mufflers & has the mounting brackets welded in the proper place for stock hangers. Here is the link to the system I have. It says on the muffler Xcelerator turbo muffler & the body of the muffler is 14" long.

67-69 2 1/2" TURBO DUAL EXHAUST SYSTEM WORKS WITH ORIGINAL STYLE 67-69 HANGER KIT TRIM TAIL PIPES OR USE OUR TURNDOWNS (virginiaclassicmustang.com)

Thanks, please let us know how that sounds

[Mike65 476]

16 hours ago, Mach1 Driver said:

Thanks, please let us know how that sounds

Terry, it might take a while before it is running since I am still doing the wiring, then I have to run fuel lines & decide EFI or carb.