DVG73

I am starting to put my engine together and the headers are the next thing on the agenda. I am building a 383 and have read differing opinions on the size of the header tubes to use. I am using an eagle rotating assembly with flat tops, XE274 cam, vortec heads, and a bootleg RPM Airgap intake with either a 650 or 750 Holley (help here to on which one to use). I plan on using 2.5" exhaust pipes

Whatcha think?

Corey_68

I'd go w/ the 1 3/4 tubes for a 383. For a 327-350 I stay with 1 5/8 for the torque, but with 383ci you can sacrifice a little to gain more top end.

:cheers:

Shark Racer

Lingenfelter reccommends 1 5/8" up to 400 hp for a 350. 400 and over, he recommends 1 3/4".

He recommends 1 3/4" all around for a 383.

-Steve

dath

I'll be running 1 5/8" with my 383, but that is partially because I already have them. I may end up changing them in the future if it seems too stopped up for the ~465HP I should be laying down. I played with desktop dyno a bit and it didn't make a huge difference, but it did make some difference. Of course when I hit the nitrous, well, I may be way too stopped up, we'll just have to see:D

Jack71

I'll be running 1 5/8 with my 406. I'm building for power from idle up to 5500 though, so torque is key for me. I modeled both in DD2000 and it didn't make that much of a difference for me.

The Money Pit

My 406 will turn 6500+rpms easy with 1 5/8" primary tubes.I had them on the 355 and kept them for the 406. Check out my website on the buildup page there's a link to a magazine article that dynoed both small/large tube headers on the same 406.You wouldn't believe it but the small tubes were the better choice.

DVG73

Thanks for the responses. I have a set of 1 5/8 from the other engine, I may go ahead and keep them just to save some $$$ so I can buy more parts.

flynhi

I tried to build for torque so my 383 has large runner tpi and headers with 1 5/8" primaries into a 4-2-1 collector. Seems to work: dyno is a little over 500 ft lbs.

The Dude

:withstupid:
Same situation over here.

1969Vette383

Always save money for the intent of buying more parts :thumbs: I'm rebuilding my 350 and I'm going with Hooker Comp. Headers; I believe these are 1 5/8. I can't wait to have my car on the road with headers, never driven a car with them on :D
Headers->2.5" exhaust->Spin Tech mufflers->18" long x 3" diameter tips... mmmmm RUMBLE RUMBLE

DVG73

1969vette350,

Drive with them Open around the block once it's a kick, but once is all you'll get as the cops will be after you when the neighbors complain.

74-Roadster

Sounds like you're coming along nicely Doug! We need to see pics of the chassis. :yesnod: