/6 single or dual exhaust?

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DART DAD

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I picked up a very nice grandpa 1975 Dart Swinger special with 37,000 miles. My 15 year old son and myself are building this as a daily driver for him. We already have a 1975 Duster lmost done that will be 90% track. Even though the 75 swinger is getting a few upgrades such as super six 2 bbl set up, a 8 3/4 3:55 posi rear end I have extra new paint and the heads milled down .050 which should put me at about 9:1 compression. Well now that you have the facts, I plan on using a 2 1/4 pipe. Should I have them run a "Y" off that and use 2 cherry bombs, Run a sinle pipe into a flowmaster that has 2 exit pipes, or stick to one pipe straight back with a thrush or something simular. I am keeping the original exhaust manifold and have the matching 2 bbl. I do have a set of headers cant find a name on them, put a sticker with part number 10-500? I also have a Aluminum super six welded intake. i can see some hailine cracks in the bowl, but it was pressure tested and is fine. I am hoping to still get about 18-20 mpg. What ever parts I dont use, I will be selling along with an edelbrock RPM preformer for a small block v-8, with a holley avenger 670.
 
Dart Dad, kind of overkill on the exhaust. Not much of a point having a single pipe coming off a stock manifold only to go to a Y to two cherry bombs and out the back. IMO it would only be more weight which actually will slow the car down and it will do zip for performance. With a single manifold pipe best to stick with single exhaust. You are not going to get any better sound or performance with duals that way. If you want that sound slants are famous for with mods you gotta do split hedders or 'Dutra Duals'. Ever heard a slant with true duals, (AWESOME)!!! Kind of sounds like a top fuel funny car.

I think you could get some better performance with 2 1/2 all the way from stem to stern with a nice flowmaster or a like muffler. Stay away from that aluminum super six intake. They are nice but are known for the crappy welding and leaks. Post a pic of them hedders. We may be able to figure what they are. With that .050 head you might want to consider hedders. Your going to lose most of that milling with single exhaust. Too bad you could not have had some porting on that head. THAT is where the HP is lost.
Chas.
 
I have headers with 2 1/4 duals and thrush welded 2 chamber mufflers. Sounds like a V8 below 2500 rpm . Have gotten alot of complimence on the sound. Good luck with your project. Tom
 
you can bore the original exhaust manifold to 2 1/4 inches and run a 2 1/4 in pipe (single) all the way back. Simple and lighter, and cheaper and more than adequate. Super six well tuned will yield 20 mpg city and 25 highway (well at least mine does) Electronic ignition helps too along with a well curved distributor and some advanced timing
 
you can bore the original exhaust manifold to 2 1/4 inches and run a 2 1/4 in pipe (single) all the way back. Simple and lighter, and cheaper and more than adequate. Super six well tuned will yield 20 mpg city and 25 highway (well at least mine does) Electronic ignition helps too along with a well curved distributor and some advanced timing
Sounds good, what type of muffler are you running. God sound. Remember Im looking to build an all out car, this is just a cool ride for my son 16yrs old.
 
Dart Dad, kind of overkill on the exhaust. Not much of a point having a single pipe coming off a stock manifold only to go to a Y to two cherry bombs and out the back. IMO it would only be more weight which actually will slow the car down and it will do zip for performance. With a single manifold pipe best to stick with single exhaust. You are not going to get any better sound or performance with duals that way. If you want that sound slants are famous for with mods you gotta do split hedders or 'Dutra Duals'. Ever heard a slant with true duals, (AWESOME)!!! Kind of sounds like a top fuel funny car.

I think you could get some better performance with 2 1/2 all the way from stem to stern with a nice flowmaster or a like muffler. Stay away from that aluminum super six intake. They are nice but are known for the crappy welding and leaks. Post a pic of them hedders. We may be able to figure what they are. With that .050 head you might want to consider hedders. Your going to lose most of that milling with single exhaust. Too bad you could not have had some porting on that head. THAT is where the HP is lost.
Chas.
Lots of good info. First I will get some photos poster a litle later. ( I need my wifes help with that) I am familiar with the Dutras. Here is a question, right now I have the 1 bbl with factory stock. What a dog... However once it warms up it does run smooth. My concern is if I use the stright headers will I need a manual choke? Also on the head, I didnt want to over modify. In my thought picking up the compression without opening up the valves woulds still leave decent MPG. Here is a picture of a highway 61 model that I'm trying to duplicate.
1971-DODGE-DART-340-SWINGER-YELLOW-1-18-HIGHWAY-61_W0QQitemZ130284697531QQcmdZViewItemQQptZDiecast_Vehicles
 
I have headers with 2 1/4 duals and thrush welded 2 chamber mufflers. Sounds like a V8 below 2500 rpm . Have gotten alot of complimence on the sound. Good luck with your project. Tom
Is it the Thrush that is like 33 inches long and has 2 exit ports?
 
I have a Highly modified slant that get 20-25 MPG so dont worry about getting the bigger valves and 9-9.5 cr.
Frank
 
I have headers with 2 1/4 duals and thrush welded 2 chamber mufflers. Sounds like a V8 below 2500 rpm . Have gotten alot of complimence on the sound. Good luck with your project. Tom

I'll agree with that! Sounds awsome. I heard Tom cruising down the street
last week and you'd never know it was a leaning tower of power under the hood. toolmanmike
 
Here's what I did. I bought a flowmaster for a Silverado which had a single intake and dual outlets. I put a set of Megaphone tips on it as well. My muffler guy said it will sound like crap but installed it anyway. To his surprise it sounds like a bigblock. Everywhere I went people allways asked if it had a 440 in it. It seemed to lose a little bottom end but gained some up top. I will do it again except no megaphoneys and tuck some turndowns behind the bumper. I used stock manifold.
 
I have dual exhaust from the headers back ,just like a v8. The part number for the mufflers is 17655, they are about $35.00 each.
 
The 73 has an oversized exhaust manifold running through a 2¼ inch pipe and a generic Turbo muffler. It sounds okay. Actually it sounds kind of wicked when idling slowly in gear and is nearly silent at highway speeds.

Gas mileage is really crappy right now, 16 mpg highway. The carb was jetted with a 62, should have been a 52. Will report on thread later (see Resurrected Junk).
 
go with one big pipe unless you are going to run some kind of split manifold or header. i made my system, a 2.5" mandrel bent system with a super turbo and a glass pack for a resonator. its quiet enough that i dont feel bad for the nieghbors when i decide to start it at 530 when i use it as a daily driver. its got a pretty good sound when i rev it up though. im not really into the loud 6 cylinder sound, i didnt really liek the way it sounded with just the turbo muffler.
 
Not trying to make anyone mad, but.....unless the exhaust manifold is split, inline 6's sound like a mail truck. I hope your header setup is! When they ARE split, I think they sound better than a V-8......such a tough sound......like music!

One thing with headers though and that is you'll have to fab up some sort of carb heat source to prevent carb/intake icing in the morning, since you won't have a hot exhaust manifold bolted to the intake any more.
 
I think it's great that you are doing this car for your son. I'd go with the dutra duals that way you can still have heated air for your carb and it won't ice up, as well as manifold heat under the carb.
Good luck with the project.
Tom.
 
Too big a pipe (dual 2 1/2") won't dry out as fast when driving. It will rust out fast.

Will probably hurt MPG's. I did stock sized pipe into duals for my Duster through dual generic round turbo mufflers. Nice rumble at idle quiet on the highway out the rear. it had a drone under 70 mph.

I now have headers with the same system with a cross over H pipe to quiet it.
 
Not trying to make anyone mad, but.....unless the exhaust manifold is split, inline 6's sound like a mail truck. I hope your header setup is! When they ARE split, I think they sound better than a V-8......such a tough sound......like music!

I've said many times that my exhaust (Dutra Duals through turbo muffs and true dual exhaust) sounds like a vintage WWII fighter plane when I'm on the highway. Like a V-8? No. Way better. :)
 
Lots of good info. First I will get some photos poster a litle later. ( I need my wifes help with that) I am familiar with the Dutras. Here is a question, right now I have the 1 bbl with factory stock. What a dog... However once it warms up it does run smooth. My concern is if I use the stright headers will I need a manual choke?

No. You can rig the choke up to the intake using a stock muffler clamp and a little third world engineering. The choke is a little slower to release, but it works. The choke coil rests in between intake runners and is bolted to clamp on intake. Also had to add 3/4" spacers under intake to preserve throttle and kickdown function.

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This is a late message, but I finally got my son's Dart up and running. I took you advise and went with the thrush and Clifford headers......WOW!!!! It sounds like a small V8.. Most people think it is a 318.. I opened the valves, upped the compression, and made a 2bbl set up. He is terrorizing the subdivision doing laps...His smile says it all!!!!!!! Thank You, Thank You, Thank You..I am officially the best Dad in the world. We went with citron-yells go-wing, slit scoops, and chromed rallies. He got creative with the interior and we used seat covers that are black and yellow, Also dyed the door panels yellow, and everything else black. It looks like a Dick Tracy mobile, only my son has no idea who Dick Tracey is. I'll get some pictures up on my build. Everyone was such a great help.
 
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