I'm still in the construction stage of my 51 Henry J gasser style bracket car. I'm going to use the pump gas friendly 440 from my cuda streetcar and I'm going to have to fabricate some headers for it. I was given 2 sets of A body fenderwell headers to cut up and modify to fit which should be an interesting project, but both sets of headers are very large tube, one set is 2.25" and the other is 2.125". I understand that there is an optimum size for any given application and that these are much larger than would be optimal for my iron headed street motor. The 440 presently makes an estimated 450-475 hp and pushed my 3400 lb 71 cuda to consistent low 12s with a crower hyd. cam, holley street dom intake w/750 vac sec holley, 1.75" hooker comp headers, home ported 906 heads with 2.14/1.81 valves and 3500 stall converter. In the HJ I will be switching to a single 4 tunnel ram w/ 850DP and solid cam yet to be chosen, with a 5.13 rear gear with 32 inch slicks, all else will be left as is for the present time. My question is how much power will the oversize header tubes cost me and will there be any other problems associated. Would I be far better off to modify the smaller headers, or would the difference be no big deal in a bracket car? I'm estimating the HJ will weigh about 2200-2400 lbs and hoping this combo will get me into the 10s.

The first motor I built and dyno tested (pump gas 426 C.I. cross ram M.W. 9.4 to 1 comp) started the dyno tests with a set of Hooker A body headers, 2.0 inch primarys, 42 inches long and 3.5 collectors around 12 inches long. The dyno operator made a set of dyno headers, 2.25 diameter primary pipes around 25 inches long with a four inch colletor around 10 inches long after the transistions, that stupid motor made more power and torque from 2500 RPM and up with the bigger pipes Fooled me a bunch Use the ones that you like the most

i haVe been 8.40's at 159- 160 at 3500lbs.....how much hp is that?? and i use 2" Proparts header. I cant see you needing more than a 2" header.

If you plan on a big motor in the future, you can go 2.125 up to about 850+ hp and 2.25 above that. You can also build step headers, which will give you more tube to work with.
I run 2.125 x 30 x 4 inch headers on my 528. IMHO build for the future. And don't forget to leave room for different deck heights, and exhaust port locations.

"i haVe been 8.40's at 159- 160 at 3500lbs.....how much hp is that?? and i use 2" Proparts header. I cant see you needing more than a 2" header. "
We also have been 8.62/161 @3660 lbs. with 2- 2-1/8 step headers with a 1.31 short time!
Mike

I'm running 2" Proparts on my 500" low deck but I'm dying to try a set of those 2 1/8" TTI step headers.

Thanks, future plans would include an aluminum head stroker, and hopefully not have to build another set of headers. The hopes for this car is to have a light fast fun car that doesn't break parts, and use as much as I can of stuff I've already got. The 440 will likely find its way back into the cuda eventually and I'll probably buid a B stroker. Its the first dedicated race-only car I've built, but I've had a few street/strip cars that have always run hard because I've used well thought out combinations, so I wanted to make sure the big tubes wouldn't cause problems for an otherwise great running engine. I like the step header idea, as said it frees up some more tubing. How far from the port flange should the step be? And does anyone have suggestions for a solid cam for this combo? CR is 10:1, and I'll probably use a set of DC 1.5:1 adjustable rockers I have collecting dust. I'm just keeping my fingers crossed that my "tape measure and chalk marks on the floor" suspension engineering will launch straight. Its got a 36 Dodge 'wavy tube' front axle, 4 bar, cross steering with hemi-cuda steering box, Aston Martin disc brakes etc, but that's another post...

I'd love to see more of the paint job on that Henry J!

I wonder if cylinder pressure during combustion has anything to do with header size?

For D-Brad, a better look at the paint. What rear gears should I use with this acid flashback color combo?

Dave your combo is so mild, So Im going to say your header primarys as listed, fit in the WAY too big catagory. The biggest Id build would be a 2" and make them long like 36"

There are header primary charts and calculaters out there, and Im going to say your build as stated will fall in the 1.3/4 to 1.7/8 range.

Your car is super light, so a 2" header wont hurt you to much.

If your not all about "Top performance" and want the "Cool factor" I say build yourself the 2.1/8 stepped into the 2.1/4. Your car itself has a Major Cool Factor allready!! Keep with the theme, IMO mike