1-3/4 or 1-7/8 for a 383

[JimmyD]

OK, the details. 383 "Skip White" Long block, NKB 200 heads, Air gap intake and 750 cfm carb. Est. 450 hp. What size headers ?, and any brands recomended ? Just a nice strong street cruiser engine.
Thanks ahead of time to all you G-body Guru's.

 

[Built6spdMCSS]

1 3/4" Primary.

 

[bracketchev1221]

1 3/4 is big enough. Just make sure you get good port coverage. For what you’re doing 1 5/8” is fine but with most aluminum heads the headers don’t give enough to seal the edges of the port and you get gasket leaks

 

[64nailhead]

1 7/8 will flow more and make more HP if, repeat IF, your motor and heads need it. But I doubt they do for a 450HP setup.

A set of 1 1/2 will be more responsive at low rpm’s, but barely noticeable AFAIC. And a smaller tube will have more of an issue that bracketchev1221 was describing with port coverage.

 

[JimmyD]

Thank's "64nailhead", I'm thinking 1-3/4" for what I'm looking for will be good, "bracketchev1221" Thank's for the head's up, I hav'nt seen these NKB-200 heads yet, but "565bbchevy" gave a ok on one of his builds, and Hey, "Built6spdMCSS" Short and to the point, I'm not an LS guy, 'BUT' More power to you. Thank's everybody. This is the "Place" for G-body. Period. Now, 1-3/4" headers for an elky, '81 kinda sorta '85 is'h, lol.

 

[Built6spdMCSS]

No problem, here to help. I have 1 7/8" on my Cammed 6.0l setup but it moves some air in that Engine.

 

[bracketchev1221]

I found out the hard way with a set of. Afr 195 heads. I was being honest that a 1 5/8” header was good enough for my combo, everybody likes bragging about race car parts. So I got the small headers and put them in with the recommended header gasket. The header only caught the gasket by 1/16” in some places. So I had to use the 1 1/2” gasket to prevent leaks

 

[mikester]

I have 1 3/4 Shoenfelds on my 406. They fit well but cant be used with AC. I have heat only. I also had to send them out to get coated.

 

[Kamloops cutlass]

I used 1 3/4” x 3” hooker super comps on my 425+hp 383 they were WAY better than the headman headers I had on it previously .

 

[86Prix]

My advice on headers is always get ceramic coated and if ultimate performance isn't your goal mid lengths tend to fit better, tighter, and are more friendly on speed bumps! Also set a budget and no need to spend $1000 either. There are lots of great street car headers out there that are just fine 99% of the time just avoid the cheap eBay Chinese junk. I bought great open box and "test fit only" used headers from eBay and Craigslist for all 3 of our cars for a fraction of their new price. M2C