I am looking at building a stroked 400 SBC for my '86 Firebird and was wondering if I needed special headers for the 400 or would 350 headers bolt right up? With the larger motor am I going to have exhaust space problems under the hood? I am going to use the Motown SBC 220 street heads, in case that makes a difference. Any help would be appreciated.

 

i dont know about those heads but a sbc 400 is the same size on the outside as a 350,305, etc.
they even can use the same heads, and same manifolds.
what crank are you going to use for this "stroked" 400.?
i think you need to do a littlle more "looking".

 

I think you are going to need 1 3/4" headers to use a 427 to its potential. I would suggest the Hooker long tubes. And for the cost, I would get them coated. They aren't cheap to keep buying over and over again.

 

You can buy kits to stroke a 400 for around $1,000, they are aftermarket obviously because there isn't a bigger small block crank you can use. As for getting them coated, you're absolutely right. They're going to be coated inside and out, now that I know the 350 headers can work on a 427. I'll look into the 1 3/4". Should I run a 3" inch dual exhaust all the way or would a 2.5-2.75" work just as well?

 

For that kind of engine I would even suggest running 1 7/8 headers with dual 3 inch pipes. That sounds like one beast of an engine you're building and it will need all the breathing it can get.

 

I'll second the 3" pipes idea. Its going to be a tight fit under there, but I think you could use everybit of dual 3".

 

I only plan on making around 500 HP, isn't a 1 7/8" a little excessive? I didn't realize my Firebird would be a tight fit with the 3" dual exhaust. (I'm rather dissapointed to hear that.) Thanks for all of the help.

 

A buddy of mine runs a 427 SBC that puts out 725 hp & he runs the Hooker 1-3/4" longtubes. It hasn't keep him from running 9 second 1/4's. His exhaust is dual 3-1/2" pipes with Borla race mufflers & dumps.

 

If you don't want to do the duals you could go to www.mufflex-performance.com and get a bigger catback system like a 3.5" or 4" system.

 

500hp would be easy with the 427, but parts for a 383 would be cheaper, and could make the same power at a reasonably low rpm. Not wanting to start a war here, but I would be running a 427 to some high numbers if I were building one.

 

I can break the 500+ barrier so much easier with a 427 and I'm looking at making around 550 HP. The 427 bottom end is only about $300 more than a 383 kit and everything else costs the same. I appreciate the input though. Besides a 427 SBC just sounds so much cooler than a 383 SBC.

 

Bigger bore = bigger valves.
Better bore to stroke ratio.
I'd go with the 427 too.

 

I would have thought the 427 would cost a lot more than that compared to a 383. If thats all it runs, I would take the 427 any day.

 

I was pleasantly surprised also. THe only thing more expensive than a 383 is the initial stroke kit and like I said that's only a few hundred more; and everything else works with either a 400+ or 350+ SBC....