Ford-FE 484 header diameter and length. no shock towers.

[HRTATK1]

Hello All,
I have a Shelby Aluminum 484 with Keith Craft CNC stage II edelbrock 6008 heads and edelbrock victor efi 4500 intake. I was wondering if anyone has suggestions on primary header tube diameter and length as well as the collector diameter and length.
This is a Hydraulic roller motor with FAST XFI 2.0 with ITC. This is going in 67 Fairlane 500 with C4 auto and gear vendors coupled to a 9' 3.70:1 35sp Detroit locker rearend.
When on Dyno with the Wilson 4150 throttle body and large dyno headers, the engine made 553HP @ 5600 and 555TQ @ 4900. I expected the HP to be over 600 for this build. I am hoping with the upgraded intake and throttle body as well as good flowing headers, I can get to 620HP or so. Duration on cam @0.050 was 242/248.
Exhaust valve size is 1.75".. Please let me know if you have any suggestions or need any more info. This is a 4.255 bore, 4.25" stroke motor at ~10.6:1 compression.
Thanks, Josh

[jerry clayton]

My rule of thumb for street header size is minimum of 1/4 inch over the exhaust valve size-----in your case would be 2 inches minimum------------

[HRTATK1]

Hello Jerry,
Thanks for the info. Do you know how long my primary tube should be?
Josh

[jerry clayton]

In that car-you said no shock towers????????? with that size engine, and that stroke, the tuning of the primary tubes won't be as important as just getting the exhaust out of the cylinder/head and away from the motor--------your first bend or two will be criticle as well as how you merge the tubes to the collector-probably more than the primary tube lengths-having said that---I usually look at seeing if I can alternate tube lengths according to firing order to end up with two combos of primaries about 3 or 4 inches different simply so as not to tune in the engine at a particular rpm but broaden out the tune rpm?????????????? If you look at some of my old records--it musta worked!!!!!!!!!!

[HRTATK1]

Thanks. No shock towers is correct. I installed Heidts super ride II IFS and their Triangulated 4 link in the back.
Ok, I will try to figure the best way to alternate tube length. I would definitely agree it has worked for you!!.

[jerry clayton]

I had a 66 Comet 390gt and a 68 torino cobra jet----those schock towers were nasty-----------------


I see you are from Litchfield----------I grew up at Scottville, Il-hung out at Carlinville a lot( drive in movie)
was Litchfield where we played grade school basketball in a barn????????

[Rrumbler]

https://www.google.com/?gws_rd=ssl#q...e+displacement

Lots of info and reading, many different angles and ideas. Enjoy.

.

[HRTATK1]

Thanks for the links. I have been looking at some of those. I also like to know what works best from experience.

Jerry, Small world. I did live in Litchfield, but went to Carlinville from 8th grade on and then Blackburn.
I have been working on this Fairlane since about 4th grade. I originally started on the one I used to ride in as a kid with my dad but then determined it was cost prohibitive and then purchased another that was in better condition to restore.
I also have a 50 F1 flat head v8 and a 49 f4 that I placed on an f150 frame with a 351C-4v.