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Author
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Topic: Routing 3" Exhaust
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Scott (69Mach)
Gearhead Posts: 796
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 04-07-2002 01:00 PM
   
After a lot of thinking, I decided it's not in my best interest to run around with open headers.  I'd like to run a 3" exhaust all the way to the rear valence of the '69 ala stock, but the local muffler guy told me he couldn't get the 3" up and over the axle - not enough clearance. Is this just a pipe dream??? I also thought about splitting the 3" into two 2" pipes to go over the axle. I'd like to keep the exhaust exiting in the stock location if possible, but need 3" to dump all the fumes without backpressure when I squeeze it.Any other thoughts are appreciated. Thanks, Scott
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-07-2002 03:06 PM
I have a full 3" system going into a 68 Cougar at Foley Bros custom shop in Redwood City right now. If the car were lowered it couldn't be done. I found a couple of shops that'll bend 3" but it'll flow less than 2 1/2" because of how much the bender squeezes the pipe closed so this one is being done with pieces and will cost my client as much as some folks spend on their whole car. Your idea of using 2 2" tail pipes per side would work just as well (maybe better) and probably cost less than a good flowing 3" and just about any shop could do it unlike 3" that only a couple of shops can handle. ------------------
If at first you don't suceed, sky diving is not the sport for you.
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futurattraction
Gearhead Posts: 108
From: Iowa City, IA
Registered: Oct 2001
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posted 04-07-2002 03:35 PM
Hi Scott,
I'm not familiar with your Mustang. Are you running factory fuel tank and leaf springs? I'd think you ought to be able to run 3" on your car. The thing is, you may have to fabricate it yourself, since trying to find someone who can/will do custom mandrel bent exhaust of that size is probably hard to locate, and I'm not aware of 3" prefabbed systems for your car. Although not everybody is as nutty as me, I ordered a bunch of 16ga Hooker 3" mandrel bends and got some 3" straight pipe locally,and fabbed a full length exhaust. I'd think it would be easier to do with leaf springs than it was with my factory 4-link style suspension and panard bar to work around/through. I just started at the front and worked rearward tacking and fitting as I went. I enlisted the help of a guy I know at the local muffler shop to cut the angles on the tubing for me. It went fine; it just took some time to get it all put together. The one thing I did have to do was remove the stock fuel tank and replace it with a fuel cell, which I was going to do anyway, to make room for the right-hand tail pipe. Sorry for the long post... 
Best wishes,
Scott Phttp://www.avalon.net/~spopham/fuel_line_rhr_exhaust.JPG ------------------
79 Fairmont Futura, 351C, C6, 9-inch, plus...
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Scott (69Mach)
Gearhead Posts: 796
From: Walnut Creek, CA USA
Registered: Jun 99
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posted 04-07-2002 11:04 PM
It's running stock tank and springs. I like the idea of fabbing it myself, however, I'm anxious to run it and will probably pay someone else to do it. The more I think about it, the more I like the idea of two 2" sections over the axle. If I cut them right, they'll almost look like stock pipes.
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mach72
Gearhead Posts: 135
From: Bixby, Ok. USA
Registered: Jun 99
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posted 04-08-2002 12:20 AM
Scott, How about using the mandrel bent 2 1/2" tailpipes that flowmaster sells for about $100 through summit. I would think that 2 1/2 inch pipes would flow better than 3" pipes kinked all to hell. I would still run 3" pipe to the mufflers and use 3" in/out free flow mufflers. They make some smooth transitition reducers to go from 3" to 2 1/2". I think that this would work well since the flow will lose velocity going through the mufflers anyway. The 2 1/2" pipes may help keep the velocity up. The flowmaster tailpipe kit is designed for the 65-68 stang but could be modified to work on the 69-73 also, I would think. This is what I plan to do on my 72. Good luck, Tom
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-08-2002 09:40 AM
I would run 3" exhaust back to a set of 3" mufflers... then weld collector rings to the muffler outlets. Then, weld rings to a set of 2.5" mandrel bent tailpipes AND a set of turndowns. This would allow you run tailpipes when hauling the family around... and when it came time to make some noise, you could unbolt the tailpipes and attach the turndowns. You just weld header reducers to the tailpipes and weld the rings directly to the 3" turndowns. If you decided to get really dedicated to having nothing less than 3" exhaust, you would have to piece it together by cutting and welding 3" mandrel U-bends. I don't see the twin 2" pipes working all that well, unless they were mandrel bent. The cross sectional area of a 2" pipe is 3.14 square inches, two would be 6.28 sq. in. Two of these put together (even if they were mandrel bent) would not equal the cross sectional area of a 3" pipe, which is 7.07 sq. in. Crush bent tailpipes wouldn't even come close. I would either fab up (cut n paste) 3" tailpipes, or go the "convertible" route mentioned above, with the 2.5" flowmaster tailpipes. (4.9 sq. in.) If for whatever reason, you decide to run a two tailpipes out each side, flowmaster makes special "merge" 'Y' sections of pipe for running free flowing single exhaust systems. You could use one of these turned around... but I have a feeling you'd be disappointed with the look and performance of the finished product. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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iamblackjack
Gearhead Posts: 219
From: A small town in South East Texas ............Houston.
Registered: Jan 2002
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posted 04-09-2002 02:31 AM
I had hell getting 2 1/2" over my rear end in my '65. I've seen a roadster in a magazine where the exhaust went UNDER the rearend. I've cosidered that since my car sits dagerously low anyway.
Has anybody done this?
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-09-2002 07:04 AM
I know what you mean about making 2.5" tailpipes fit a 65-66 mustang... especially if the mufflers are very long at all. Around 12 years ago (before the $99/pair MANDREL bent Flowmaster units came out) the local muffler shop tried to make a set for my car. He bent up FIVE tailpipes before we got a set we were remotely happy with. (and they still weren't all that great) Those $99/pair Flowmasters are a GODSEND! No mustang (that needs tailpipes) should go without them. They are advertised to fit 64-73 mustangs. Everyone that has provided feedback, really likes them. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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V8 Thumper
Gearhead Posts: 4681
From: Phoenix, Arizona
Registered: Dec 2001
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posted 04-09-2002 08:04 AM
quote:
Originally posted by n2oMike:
They are advertised to fit 64-73 mustangs. Everyone that has provided feedback, really likes them.
Hey Mike... do those dump out below the rear valance? I've got a '65 GT (trumpets) that I want to use them on... I'd probably need to modify them, you think?
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Hemikiller
Gearhead Posts: 667
From: Killingworth, CT
Registered: Feb 2002
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posted 04-09-2002 12:42 PM
The Flowmaster tailpipes are great. They are extra long as to fit any 64-73 Mustang and 67-73 Cougar (which had a big butt). Anyone bought their 64-66 American Thunder complete kit yet? I'll bet it'll fit all the first gen Mustangs, as the floors are almost identical. 'Bout time they made a complete exhaust for early mustangs, there has been nothing available until now. I rememer using the crunch-bent exhaust systems from Napa, what junk, could've done a better job with a hammer and a torch! Ahhh, that was a looonnnggg time ago!
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JAAZZY
Gearhead Posts: 836
From: Bay Area, CA
Registered: Apr 2001
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posted 04-09-2002 06:45 PM
Those 2.5" Flowmasters fit great. My 65 is lowered and they were still not all that difficult for my local muffler shop to get in. They spent most of their time making sure the pipes were aligned correctly but the fit wasn't a big problem. I was there watching the whol process.
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-09-2002 07:15 PM
Thumper, they come out below the valance... but MAC also makes mandrel bent tailpipes for early mustangs. They sell one set for regular mustangs, and another for GT's. I assume the GT tailpipes are for cars like yours with the exhaust exiting through the rear valance. I believe the pipes come with their shiny coating as well. They are also a little more expensive than the Flowmaster units... maybe $159 a pair. You'll have to check to be sure.MAC has a website. If you find it, I believe the tailpipes are shown on p.18 or 19 of their .pdf catalog. I cannot vouch for the quality or fit of the MAC's. Maybe someone else here can. But they are supposed to offer a set for your application. If you don't like them, the Flowmasters can be modified by either bending, or doing a little cutting and welding. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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Dusty Kiser
Gearhead Posts: 184
From: Bethel,Oh USA
Registered: Mar 2002
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posted 04-09-2002 08:19 PM
I quote:
Originally posted by n2oMike:
Thumper, they come out below the valance... but MAC also makes mandrel bent tailpipes for early mustangs. They sell one set for regular mustangs, and another for GT's. I assume the GT tailpipes are for cars like yours with the exhaust exiting through the rear valance. I believe the pipes come with their shiny coating as well. They are also a little more expensive than the Flowmaster units... maybe $159 a pair. You'll have to check to be sure.MAC has a website. If you find it, I believe the tailpipes are shown on p.18 or 19 of their .pdf catalog. I cannot vouch for the quality or fit of the MAC's. Maybe someone else here can. But they are supposed to offer a set for your application. If you don't like them, the Flowmasters can be modified by either bending, or doing a little cutting and welding. Good Luck!
I put a set of MAC 2 1/2 off road pipes on an "89 convet for a customer and if the ones for the early cars don't fit any better, steer clear. I spent entirely too long cutting bending and rewelding the right side to clear the frame, upper link, and fuel tank and get them to exit in relation to left side.
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F551
Gearhead Posts: 266
From: Manitoba, Canada
Registered: Nov 2000
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posted 04-09-2002 08:25 PM
Why don't you check with Gary Tracy (the bright yellow 69 Pro Street). I think he has pretty big exhaust - wouldn't think the 4 link would make it any easier.His E-mail is on his "Member's Photo" page. ------------------
Fred
68 Mustang 500CID/Powerglide - "No Tubs"
86 Mustang GT Cobra
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