434 Header Size
 

Hi Guys, I am wanting to build a new set of headers for my 434 sbc and need some advice on what size I should go too.

Engine details are as follows:-

1000cfm Pro Systems 4150,
Edelbrock 2.9csa Intake manifold port matched,
Dart 18* Heads, 2.15 intake 1.6 exhaust, flow 355 @ .700 intake and 253 @ .700 exhaust
T @ D Shaft Rockers 1.6 intake and 1.55 Exhaust
Dart Little M block 4.155 bore, 9.010 deck height
JE Forged pistons part # 213107
Eagle 6" H Beam Rods ARP L19 Bolts
Eagle 4" 4340 crankshaft
Howard's roller camshaft part # 111233-10 Duration @ .050 278 intake 286 exhaust, lift at cam .450 intake .426 exhaust

Current Header is 1 7/8 primary 3 1/2 collector, car weighs 3140 lb with me in it, best 1/8th mile ET of 6.195 @ 110.4.

Thanks Dean

Both Hooker and Lemons told me 2 1/8" any thing smaller than 2" would restrict the heads. My heads are Bodix 10 RPSP with 2.150 valves and .734 lift cam useing 1.6 rockers about the same duration as your cam. I got very lucky and came across a set of Lemons 2" to 2 1/8" step headers with 4" collector which had an initial purchase price of $1350.00 with egt bungs. I got them for less than $500.00 unused, but again i was lucky and they just happened to have been made for a 1980 Malibu just like mine. my car weighs 3250lbs, but i will have to run a motor plate in the front and remove the stock motor mounts to clear the headers.

Zip.

my headers are 2" on my alcohol injected 434 with Brodix11X heads,works great!

The new headers for the 582 I will be getting from The Fab Shop will be 2 1/4 inch tubes. A lot of it will depend on your bends. Can you make a smooth bend using a size tube from flange to collector? If so, you would be able to run a smaller tube. If the bends will be hard, then you are more then likely going to have to step the header. I would suggest you give Tim at Fab Shop a call. Even if you build your own, I am sure he will point you in the right direction. 317-294-4323

X2 give Fab Shop a call, I've spoke with him a few time didnt buy anything (yet) but he was worth talking to.

Thanks for the replies, I am going to go with 2" for 8" then steped to 2 1/8 for 24" into a 4" merge.

My 461 SB2 Head engine will have 2" to 2 1/8" step, same as I ran on the 447 last year. As long as the header doesn't cover the port I'd run 1 7/8" on yours although you won't see much difference in a 2".