Treblig's doughnut?

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Com'on; a 360 in a lightweight early A-body is already a kick-azz combo without needing headers. It's still gonna burn rubber thru 2 gears or more.
It's a streeter. NEVER will it go 200mph. Never 150. Rarely even 100. Typically 65/75 maybe top of second gear now and then. And when it does, chances are the tires will be smoking most of the way, headers or not.
 
AJ/FormS said:
Com'on; a 360 in a lightweight early A-body is already a kick-azz combo without needing headers. It's still gonna burn rubber thru 2 gears or more.
It's a streeter. NEVER will it go 200mph. Never 150. Rarely even 100. Typically 65/75 maybe top of second gear now and then. And when it does, chances are the tires will be smoking most of the way, headers or not.
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True, but i don't like leaving power on the table it's just me. Manifolds are trouble free most of the time.
 
Hidden power? Re-read my post. Not every build needs headers (over 340 manifolds) nor does every owner/builder want them. Trying to max out your build? Then of course you use headers, correctly sized for your app... But that is not the goal of every build, and is not necessary for them all.
And by the way, several years ago Hot Rod did a dyno comparison of street headers vs. the hipo 340 manifolds, and the gains were negligible on a basic street-friendly motor, with the majority of the gains coming at higher rpms where street motors don't spend much time.
 
note backward facing driver side flange shape and radii

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thesiren74 said:
And I'm sure they would run a lot better with headers in the fast cars.
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And I said F.A.S.T. cars, not fast cars. It's a race series. Look it up since you're not familiar with it. I'm outta here, this is too far off the OP's topic.
 
Power is left on the table with every single build. Period. It's all a compromise of what you want to do.
 
Make sure to install the flange before welding the parts together because there's no way to get it on there after welding!! Once you install this down pipe section on the car you know how much to trim and at what angle to cut the donut so that it clears everything under the car.



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This was the first one I made for my car (below) so it looks a little different. I found that it's easier to install if made the way i made them in the first pics....better fit.



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Professor Fate said:
And I said F.A.S.T. cars, not fast cars. It's a race series. Look it up since you're not familiar with it. I'm outta here, this is too far off the OP's topic.
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I know what it is i watch it all the time yes Dave Dudek is one of my Facebook friends.
 
thesiren74 said:
I know what it is i watch it all the time yes Dave Dudek is one of my Facebook friends.
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Goody. Fine, you win, you are the horsepower god. All hail. I wish I had Facebook friends, all I know are real people. Goodbye.
 
Treblig said:
Make sure to install the flange before welding the parts together because there's no way to get it on there after welding!! Once you install this down pipe section on the car you know how much to trim and at what angle to cut the donut so that it clears everything under the car.

This was the first one I made for my car (below) so it looks a little different. I found that it's easier to install if made the way i made them in the first pics....better fit.
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That doesn't look too bad to make. Start with a 120* section, cut a wedge from the flared section, then cut be careful to install the flange section or weld in a bolt or something before closing it up. Your pictures are priceless in this adventure. Really, thank you very much. It all seems very doable now.
 
thesiren74 said:
I guess i touched a nerve lol
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Dude, seriously. Go shitpost someplace else. This thread is about solving a common issue with early A body exhaust manifolds for street cars. Nobody cares about what nascar is up to or your opinions on whether headers are better than manifolds. Sort of amazed that you can't differentiate race cars from street cars or understand that different applications require different solutions.
 
Early A were facing straight back, It's strange that they made the 340's face forward! but I had them on my '65 at one time too. Too bad I couldn't remember how it was routed under there but I do remember that I had to have manual steering..? 318's were somewhere in the middle maybe a bit back. Good luck, show us what you come up with. And tell that hack exhaust shop to expand their minds, maybe they will grow some customers. I had an exhaust shop hard weld a transverse mounted motor exhaust manifold to the entire pipe to the rear hangers. It was a matter of days before the weld cracked as the motor rocks a bit front to back under acceleration. Pro, I dont think so.
 
I’m glad I bought one of Treblig’s donuts several years ago! Had it installed with TTI downpipes and non hi-po 340 exhaust manifolds just after I did my 4bbl upgrade. Installed a min starter at the same time. Not at problem since.
 
H22A4 said:
I’m glad I bought one of Treblig’s donuts several years ago! Had it installed with TTI downpipes and non hi-po 340 exhaust manifolds just after I did my 4bbl upgrade. Installed a min starter at the same time. Not at problem since.
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Now there's a smart man!!!! :thumbsup:LOL
 
R3dplanet said:
That doesn't look too bad to make. Start with a 120* section, cut a wedge from the flared section, then cut be careful to install the flange section or weld in a bolt or something before closing it up. Your pictures are priceless in this adventure. Really, thank you very much. It all seems very doable now.
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It's not that hard if you have the exhaust manifold installed in the car and the car on a lift. Then it's easy to piece it together and make sure it clears all the other things around the engine on the driver's side before the final "bolt in". You tack everything in place then take it out and finish weld. I had to develop a universal down pipe that could be installed on any A body, it worked out well and I sold many, many of them.
 
R3dplanet said:
Dude, seriously. Go shitpost someplace else. This thread is about solving a common issue with early A body exhaust manifolds for street cars. Nobody cares about what nascar is up to or your opinions on whether headers are better than manifolds. Sort of amazed that you can't differentiate race cars from street cars or understand that different applications require different solutions.
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Working on my dads 64 valiant with a 360 that was in my duster, manifolds killed that thing!
 
Hey gang. Just a quick follow up. The new exhaust pipes are installed along with an "H" pipe aft of the transmission. It sounds great. A bit less tinny, but otherwise unchanged. None of the skull-pounding reverb I've had with other exhaust systems. I hardly notice any change in power at all for the driving I do. I'm totally pleased. The exhaust guy really complained a lot about making the driver's side bend. He refused to look at Treblig's notes posted above and was surly about the whole thing, but he was able to squeeze it all together. Victory! No more exhaust leaks!
 
340 manifolds with 120 degree (donut) vs 273 manifolds (facing rear). Don't think you could even measure the difference.
 
R3dplanet said:
That doesn't look too bad to make. Start with a 120* section, cut a wedge from the flared section, then cut be careful to install the flange section or weld in a bolt or something before closing it up. Your pictures are priceless in this adventure. Really, thank you very much. It all seems very doable now.
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If you have your car on a lift and all the pieces that you need then it's not too bad because you can piece it together on the engine and assemble all the pieces avoiding the steering, torsion bars, starter etc. I had to figure out how to make a 120 degree down pipe that was universal. It had to fit every A body without having a car on a lift to fit all the pieces together. Glad everything worked out for you and that you happy with your car!!!:thumbsup:
 
It looks like a 340 angle to me, but it has the bellmouth end so its probably the close 318 manifold model. Those are from Accurate and ask what manifold castings you are running as the 318 is a donut gasket (probably what's in pic) and the 340 is more of a less forgiving angle flange gasket as well as the altered angle.
(see option box below) -A-Body 318-340 and 360 Head pipes (P
 
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R3dplanet said:
Hey, I've ditched my headers and installed some 1971-1972 exhaust manifolds on my '65 Barracuda with a 360.

The passenger side is casting number 3618623 and fits fine. The center dumps looks reasonably straight forward to access in order to make a head pipe. The driver side casting is 3614368-2 and also fits fine, barely missing the steering column, but it's in there. The dump points slightly forward so it needs a head pipe or adapter with a pretty sharp 180 bend.

Thanks,
Red
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I have TTI headers on my 65 Barracuda now, but ran 340 manifolds for many years - first a pair of 72 manifolds, then later a pair of 68-70 hi-po manifolds.

On the passenger side with a 71-later center dump A body 340 manifold, a factory Duster 340 exhaust pipe will fit as is except you'll need to add an inch or so to the pipe after the first bend to the rear before it drops down.

On the driver's side, I have a 4 speed so there was no pipe clearance between the torsion bar and the motor. Instead, I ran the exhaust almost straight down and ran it between the torsion bar and the driver's side frame rail. There's one spot there where there's room for a 2 1/4 inch pipe to go through without rattling. From there, just run it back to the muffler. Sounds funky, but I never had a problem with it.
 
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