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Posted by Chriscase [76.212.168.173] on Friday, November 20, 2009 at 15:22:00 :
In Reply to: Re: I did build a couple jigs.... posted by Dave Horvath [12.130.9.139] on Friday, November 20, 2009 at 10:54:14 :
The B&B that came with the truck made two inches of vacuum at full speed, full throttle. Ought to be about 1/2", as it is now. Hmmm, I ought to look that up in a fan catalog, see how much the flow rate improved.
The 2bbl is probably over kill, being enough for a high revving V-8 with nearly twice the displacement. One of the larger one bbls should be adequate, but are harder to find in the junk yards. I think the Rochester Mono-jet would do, from a GM 6cyl, or the Holley from a /6? 1bbl would be easier to hook up the linkage too, I don't think my web site show the 2 bbl and the monkey motions I had to build to hook to the stock FFPW linkage.
To show you the poor flow of the 230 flat head, I found a site with a calculator for header pipes. 230 cid, times 3800rpm, should have seven foot long tubes of less than an inch in diameter. That is if you hope to get an equal length, tuned system that would actually pull intake charge out the exhaust, and then ram it back in. Supposedly something like 5-10% of the charge. Supposedly. Ideally. Yeah, sure. Well, maybe at 9,000 rpm... Anyway, smooth flow with the venturi effect in the collector of one pulse suckin the exhaust out of the other tubes is where the main improvement lies.