Indy 360-1 Header Tube size

Looking to get a set of custom headers built for my 71 Plymouth duster. Would like to know some recommendations on header tube size and length. The car as tube k-member with rack and pinion so i have plenty of room.

Some of the engine specs.(Small block)
360-1 Indy heads CNC
3.79 stroke, 4.060 bore 394 ci
14:1 comp
1050 domnator carb
roller cam ??????
weight just guessing 3000-3100lbs.

Should I builg 1 7/8-2 inch steps.
2-2 1/8 steps
or straight 2 inch.

Any suggestions or advice would be appreicited. thanks.

c.i. are little less then my 449. Ryan used the 1 7/8" into 2" Step header with 3.5" collector, i have not try any other size yet, will be cool to find extra hp/trq.i want to try a3 step w/2 inch to 2 1/8 to 2 1/4 with a 4 inch merge colector, just don't know how tight is going to be on my 65...

It would be easier to make suggestion if you had an RPM range but, since
the engine is under 400" and guessing peak power at 7300.........

1.875" x 25.5" w/3.5" x 15" collector

OR

1.875" x 13" stepped to 2.0" x 13" w/3.5" x 15" collector

I can give you specs for 3-step too.

I think the engine will peak out at around 7500-7600. Thanks for the information.

Warren, nice to see your still plugging away at it. Hope to see you out soon. BTW, straight 1 7/8" gets my vote b/c of the powerslide.

I think the flanges that Indy sells are for a 1-7/8 tube. Thats what Ryan told me over the phone. I am building 1-7/8 X 2 X 2-1/8 with a merged collector with a 2-1/2" pinch back up to 3-1/2" secondary exhaust. My Primaries will be super long since I make them to fit the car.

6400 RPM 501 Cubic Inch Indy 360-1 245CNC 48Deg Hyd Roller cam.

501".. Ron.....Why such a small, small block? LOL!!!

Quote:

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501".. Ron.....Why such a small, small block? LOL!!!

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I want to be able to rebuild it once or twice.

My vote is 1-7/8 all the way as said above. Smaller tubes will NEVER hurt you as much as some people think and if you have a powerglide the Tq would be better. The shortest tube should be 34" on an automatic car. Equal length is overrated. I don't even try.