hey guys i am looking for some info on manifolds for a 454bbc i dont want to put the long tubes on, i dont like what i was reading about. i read about 2002 avalanche 8.1 manifolds (said it was like a shorty header style) but never saw any pics. my donor motor came from a 92 3500hd and those i am hoping will fit or 88-98 shorty headers. and also do any of you know if the stock tbi manifold/tbi fits under the stock hood? other wise a good combination you like for under 5500rpm (performer rpm & 750cfm carb undecided.
and please dont say search i have been looking for months and the bbc link havent been fixed in 2yrs
thanks

 

shorty headers. Most(not all) manifolds are somewhat restrictive. A good set of shorty headers will do a better job.

 

We have a couple of great threads on this, but those manifolds you have won't both fit. One might. There are no shorties that fit correctly. Stock manifolds aren't so restrictive, but they don't help with scavenging. scavenging is why the Hookers will help a stock 454. Stock manifolds become a restriction by 400 HP, but below that, it's just the scavenging. And that falls down if the mufflers aren't good enough. Dorman makes some reproduction BBC exhaust manifolds that are known to fit, but require some firewall hammering on the passenger side. http://www.summitracing.com/parts/RNB-674-159/ is for the driver side, http://www.summitracing.com/parts/RNB-674-161/ is the passenger side.