Hopefully someone can help me out here, I desperately need a pair of exh. manifolds for a SBC, they must have a 2.5" outlet. Supposedly these were used on some early corvette applications, and some Hi-Po 327's. i have a '69 camaro Pace Car RS/SS, since it was NOM, we built an alum. head 383 for it. Only problem is the owner definately does NOT want headers, and I don't want to choke the eng. off any more than I have to. Anybody?? I have some good parts to trade, or can buy them outright. I have seen them for sale, but I can't sell off any kids to pay for someone's pride!! The one's I've seen were $250.00-300.00 , and that is way too much. I would be willing to pay about half of that for a decent set.

 

Take a pair of stock manifolds and have them Extrude Honed to smooth them out and open them up to a larger diameter. There are racing shops that port stock manifolds too, but they are pricey as well.

 

thanks, I can hand port mine if necessary, but I was saving that as a last resort. I want to start from the bigger manifold, and open that up as much as possible. The engine dyno'd at 460hp/480ft.lbs so I need all of the airflow through the manifolds that I can get. It really needs a good set of headers, but that is not an option.

 

I can't recall any original manifolds from the 67-69 Camaros that had a 2-1/2" outlet. I've seen articles and tests done on manifolds ported by Brezynski Racing that flowed within 10 hp of headers so that's pretty impressive for a stock look.

 

that is very impressive, do you know if they started with the standard 1.750" or whatever they are straight back manifolds?

 

Here's the link, I spelled their name wrong.

http://www.castheads.com/exhaust/exhaust.htm

They've been modifying stock intakes, heads and exhaust manifolds for racing classes that have to run stock components.

 

Thanks Jeff, I'll check it out.
Ed

 

The 2.5 inch exhaust manifolds found on early Corvettes is a very rare and expensive piece. They are the ram horn type and will not work in a Camaro.

 

I've seen a bezillion sets of stock SBC exhaust logs and 2.25" is as big as they go. Unless you're talking about some really rare factory piece, which I wouldn't know about. But anything you're likely to be able to buy for reasonable money...... sorry, no dice.

I even checked my Gen II LT-1 exhaust manifolds and they're still just 2.25, but using a later style gasketless flange.

 

Thanks for the input. I'm aware of the ram-horn problem. The ones I'm looking for are still a log style manifold, and I believe were offered on early to mid 60's full size SS cars with the high HP 327