Ok, first off, my combo is a little different then what's typically listed here; 1967 W200, 440, hydraulic bellhousing / NP435. The 440 is a stock bottom end 68 block with a set of nicely ported 915's with 2.14 / 1.81 (or maybe 1.88, can't recall) valves; Comp cams .495 lift 236/236 duration and a Holley 750 DP. This truck is used for competition sled pulling, but also sees alot of street driving.
Currently my headers are a set of big block Hedmans mated to a set of small block hedmans. Sounds extreme, but the hydraulic bellhousing has it's own crossmember so every header in the book hits it and I had to do what it took to get the collector low enough.
I'm going to build a set of headers myself and just looking for a good source of parts. I've got a mig, but no tig so I'd like to find a set of flanges with the stubs already welded. The tube routing will be easy as there's lots of clearance.
Not sure on tube size, I've been thinking 1 7/8" but wondered if 2" wouldn't be a better choice. I'll be tearing the motor down this winter and seeing how things are holding up, I'd like to avoid a piston change so I won't be gaining any more compression, but I am considering changing cams. We're limited to pump fuel and need to pull 14" of vacuum so cam selection is also governed. Currently I'm pulling about 15" of vacuum.
So, any advice on flanges, primary size and collector size? thanks in advance
