header tube size questions

I've dropped my little 466 off at the dyno shop and having a hard time finding a set of headers to run it with. My headers are Schoenfeld 2 1/8" uprights and need down turned ones. I have access to a set of 1 7/8" tube headers, but would rather get something cloeser to my tube size for a better comparison. I think I have a solution to the dyno delima that will get me by this weekend, but it got me thinking about tube sizes and what's really the best for my application. Here's the specs on my motor for reference:

D1 block bored .030, hardblock filled to bottom of water holes, zero decked for rotating assembly
SCAT h-beam rods
SPR forged flat top pistons with 2 valve notches
Helfire moly rings file fit for the 250 shot of NOS that the truck will see
Freelander ported and worked D0VE-C heads
Lem worked Comp solid roller cam 110lsa 268/277 @ .050 750/760 lift
Comp solid roller lifters
Crower SS roller rockers
Jomar stud Girdle
FRPP 4500 Victor intake
Holley 1150 Dominator
MSD dizzy fed from MSD 7al-2 ignition box
Schoenfield 2 1/8" upright headers
ARP head studs
ARP main studs
ARP 2000 rod bolts
Canton windage screen
Ford 370 truck 10qt oil pan with baffles added in.


I'm wanting to build a set of chassis exit headers. Thinking of starting with a BBC weld up kit (because cost is less than a BBF weld up set!), changing the flange obviously to a bbf flange, laying them back slightly to clear the spring towers and possibly stepping from 2" up to the 2 1/8" with 4" collectors. Keep in mind this is an offroad only mud truck and I'm looking for all out wot power. So would they be too large or should I just go 2" all the way?

2" with that combo IMO

IMO this is a case where my header adapters would really pay off. We've used them when we dyno and it allows us to use a multitude of BB Chevy headers that are in the inventory of the Kentucky Krew and our friends. Everything from straight 2" headers to stepped 2.375" headers.

For example I own three sets of headers that we've used at various times on Kristina Lawyer's A-460 headed engine, and as we all know the A-460 heads use a BB Chevy bolt pattern. With the header adapters, when Bobby's P-51 headed engine was on the dyno, we tried a straight set of 2.125" Chevy bolt pattern headers,,, then a set of Fab-Shop 2.125' stepped to 2.250" Chevy bolt pattern headers,,,then a straight set of 2.250" Dyno-Tech headers,,, and finally a set of straight 2.250" Fab-Shop headers. Bobby's P-51 headed 557 engine ended up making 942 Hp and we used the Fab-Shop straight 2.250" headers on his dragster. Likewise, we used the header adapters when Randy Moore's P-51 headed 562 engine was on the dyno.

Uncle Charlie

Thanks Charlie! Dave Freelander said the exact same thing to me yesterday about your adapter plates. My goal is to eventually step up to a set of A heads when the money is there, so I was runing that through my mind about just building the new headers with the bbc flange and getting your adapters to use until the next stage is done. Can you PM me a cost on a set of plates?

Hey Karl i got you covered if you need headers for the dyno session i got two sets of 2''-3-1/2'' pm sent.

Kjett I just did what you are talking about last year on my mud truck I used a BBC kit from Stahl and used Charlies adapter plates.What I found during this process is you cannot go around the coil spring cups/buckets with these kits you have to lower the cup/bucket where the top is alomost level with the frame. I managed to get mine in by lowering the cup/buckets 3 inches and buying about $200 worth of extra bends and doing a lot of cutting and welding to get them in there. Mine are 2.25 headers and 2.125 would be easier but still gonna have to lower the springs.

Karl, I tried the same kit from Stahl on my truck and it would've taken a lot of effort to make them work on the 80's frames too. I was real happy when Maddog finally came out with some headers for these trucks. I don't know if you would be able to use them or not or the price, but Hedman makes a set of 2" headers for the 70's F150's. BTW Charlies adapters are great, especially when going to the larger diameter pipes. They make it a lot easier to install the bolts and the pipes aren't all pinched down at the flange. Definately a must do IMHO. I don't know if the Maddogs like I have would fit, but I still have mine up for sale at a reasonable price and they do have the BBC pattern flange on them.

Bryan,

Thanks for the offer! PM sent back to ya!

I originally went with the 2 1/8" tubes with the plan to eventually build something bigger than a 466. What is the point at which to make the jump from 2" to 2 1/8" to 2 1/4"? Or is it all a matter of testing/tuning/trying out?

kjett wrote:Thanks Charlie! Dave Freelander said the exact same thing to me yesterday about your adapter plates. My goal is to eventually step up to a set of A heads when the money is there, so I was runing that through my mind about just building the new headers with the bbc flange and getting your adapters to use until the next stage is done. Can you PM me a cost on a set of plates?

kjett,

The adapter plates are $225 plus shipping.

Thanks,

Charlie