What Manifolds for a Mild 318 Build?

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Haney

Haney

www.carsonandironmt.com
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I am currently working on my 72 Dart that is my daily driver. It is currently getting a brake, suspension, wheel/tire upgrade. My main goal with this car is to have a great driving classic car that has a good balance between handeling, ride, power and MPG.

After all my suspenion mods, I want to put dual exhaust on the car. Before I do that I need to decide on what manifolds/headers to use.

As stated above, this will not be a street stip car, but a daily driver. It is currently a bone stock 72 318, factory 2bbl, factory 1972 318 manifolds and single exhaust. It is a 904 with a 2.76 rear. The rear will be changed during my mods to a 8 3/4 rear with 3.23 gears.

Plans for the motor will be a new cam, probalby a 340 type grind or a XE256 or XE362 or equavalent, EDDY performer intake and a 600 Holley style Carb with Vac. Sec.

So, my question. What exhaust system confiquration would you use to achieve my goals? I would like to see 300 hp (flywheel) and get decent MPG reliable daily driver that sounds good. I like the idea of manifolds over headers? Is it necessary to upgrade to 340 manifolds? If so, which ones to meet my goals? Early or later......

Thanks for your opnions, comments and thoughts....
 
Run the same size or larger pipe than your manifold/header collector.

The best intake IMO for your combo is the eddy perf RPM.
 
Agreed on keeping the 318 exhaust manifolds and pipe size there after or to the next size up. I'd re think the cam and take a peak at the Comp Cam line up. They have a line of cams designed for use with exhaust manifolds.
 
Stock iron manifolds with 2.25" dual exhaust will be just fine. Next upgrade would be magnums, then 68-71 340 manifolds or garden variety headers. From 72 on all A-body V8 manifolds were basically the same, so any later manifolds are about the same as what you have now.
 
I'll be running 68-70 340 exhaust manifolds with 2.25 exhaust on my 70 Dart with a warmed up 318.
 
Haney said:
The XE cams mentioned above are Comp Cams...
Click to expand...

Yea, we knew that. ;)

Check out the other line as well. It has more exhaust duration by a good margin due to the restrictive manifolds.
 
Haney, I think Rumble is thinking of the Dual energy line.

Our build are pretty similar. Mine is going to be a stock 318 long block, 340 TQ carb, Intake and exhaust manifolds, Pypes 2.5" x pipe exhaust. For a cam Im going with a Comp Cams HE268 because its being donated LOL. Its pretty close to the intake side of the XE256. Transmission is going to be a 904, Trans Go TF2 and a Turbo Action 11" conveter, Gears will be 323s
 
C130 Chief said:
I think the Thumpr line has a pretty split pattern.
Click to expand...

I'm sold on the Tumper line. Just built a big block with the middle of the road thumper cam with a mild set of heads on it and a 750 carb. It went 505 hp and 545 ft lbs. SOunds great too
 
Does your car have power steering? If so, the drivers side will limit some of your choices on manifolds. If you do not have power steering, then there are some 360 manifolds that have bigger ports that can add a little flow. These are fairly easy to get and are low cost
 
I have power steering..... Looks as for my build, I will be leaving very liittle on the table by using my current manifolds.....
 
Your originals can be upgraded by using a dremel to remove rough casting and flash in the ports, and slightly enlarging the entrance of the ports to be sure the exhaust manifold will overlap the head port. Also, extrude honing can help your manifolds perform...
 
Dont bother cleaning them up. I know a few guys that spent timing trying to port then and spent money on extrude honing them only to run the same numbers after. Not worth the investment
 
Haven't tried them in an A-body yet, but 95-96 magnum manifolds are about 2.25 outlet, and seem to fit real nice in my big ol C-body. Mopar tested flow of the early magnum manifolds, which were 1.875 outlet, and found them to flow nearly equal to the 68-70 340 pieces.

My engine is a 318, .030 over, 9.5 CR, 284/.484 cam, iron TQ intake, eddy 1405 carb, and a stock 68 340 air cleaner. Exhaust is 2.25 from the manifolds to straight thru glass packs under the rear seat, then 2 inch tailpipes with some factory tips. Cackles like mad, and doesn't run bad for a small engine in a heavy-*** 4 door Polara.
 
If interested, I have a set of 92 Dakota manifolds with 2-1/8" outlets. They were wire brushed and heat painted. Bought these for a mild 318 build in my black 66 Cuda, they would not clear the steering shaft. Later model A bodies have more room. PM me an E-mail for pics.
 
The cheapest junk headers will be a improvement in power and MPG over any a body 318 manifold
 
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