[GTO-relic]

quote:
"Barry Grant started that inflated cfm number crap years ago. Well Barry is gone, Holley owns his company and his carbs, and the cow is out of the barn. "

whoever posted this, you need to do some research.

BG Demon carbs were wet flowed at 1.5" HG/20.4" water. The corresponding DRY FLOW number would actually be approx. 7.6% more than what BG rated them at, compared to a Holley, because Holley DRY FLOWS their carbs for rating. BG also gained 6% discharge coefficient for the patented scalloped air entry on the Race Demon carbs at that time, compared to a Road Demon/Street Demon with a choke horn on it. the BG owned Demon Carb. company put their test specs in writing, it's on page 44 of the Demon Carburetor manual.

so, right off the bat with an "old" vintage BG-era Demon, you can add 7.6% to their stated flow rating, and also get a 6% better discharge coefficient for then-patented scalloped entry, compared to a POS Holley w/choke that now costs $1 per cfm new. This is why used Demon carbs are flying off Ebay and Craigslist lately like hotcakes for $250-$400 each, and new Holleys are sitting with no bidders or buyers at $500-$800+. The fact that many new Holleys have Chinese, Mexican, etc. parts, and the ones still made in USA have very poor finishing QC, isn't helping matters any- Holley is now a holding company owned by people who don't even like cars, they just want ROI, and aren't even Americans, and would like all our cars crushed, and for us to go electric across the board. wake up. the NWO corporate money grabbers are in our hot rod kitchen. they now own it.

so...BG wasn't flowing carbs at 28" water, and inflating numbers. He was wet flowing at 1.5"HG/20.4"water and advertising REAL numbers. He even used fluids in the flow tests, with same specific gravity as the fuels that would be used in the car. Take any vintage Demon, multiply it's rating by 1.076 right off the bat, that's what it dry flows compared to a Holley. If it's a Race Demon, you're getting another 6% discharge coefficient for the scalloped entry, compared to anything with a choke horn still on it, even if the choke plate is removed. The scalloped entry also equalizes the front and rear barrels, as a stock Holley primaries are restricted by the clunky 1950's design choke horn.

what he DID do, was bore out the venturis of the carbs, over what Holley offered, right off the reel. BG "750" had a 1.40" venturi. Holley 750 was 1-3/8" venturis, approx. 1.375"

so...a vintage BG 750 was bored out .025" on all 4 barrels, with the standard 1-11/16" throttle plates. His "750" scalloped entry Race Demon carb, wet flowed, actually flowed around 807cfm dry flowed, that's more than a Holley 800 DP 4780, or 780 3310, which were rated by Holley using DRY FLOW.

The vintage 825 Race Demon, had 1.42" venturis, i.e. bored out another .020" over the 750 Race Demon venturi size- but it used an 850 Holley 1-3/4" throttle baseplate. Yet he only rated it at 825 cfm. Holley puts an 850 baseplate on their 750 main body, and calls it a 950. So who was inflating the numbers here ? Again, add 7.6% to the BG 825 for a dry flow number, it's actually an 888cfm carb, if compared to a Holley. Holley fudged way over that number, to 950 in their advertising, for the same baseplate/venturi combination.

BG used this approach right across the board on all their carbs. I have one of his old Holley reworks with the BG stickers on the bowls, from his pre-Demon era. All 4 barrels are bored out .025" over the stock Holley 750 size, to 1.400" - and the top is completely scalloped like a modern Holley HP. Actually Holley COPIED the BG reworked carbs to make their new HP's. Prior to that, Holley HP carbs just had the choke horn milled level with the air cleaner mounting ring. There was still a remnant of the choke horn protruding on early Holley HP carbs. BG also managed to get from 975-1025 cfm from the Holley 850 1-3/4" baseplate -- 1-9/16" venturi combination (1.562"). There was a Demon 950 with 1-3/4" throttles, 1.500" venturi, and a Demon 1050cfm carb, with 1-3/4" baseplate, and 1.59" venturi. That was a stock Holley 850 venturi opened up .030"

He did it with wider selection of venturi sizes, up/down from what Holley offered, and the superior scalloped air entry, better boosters, and higher discharge coefficient.

BG came right out and said, race motors will produce a depression of 6" water at WOT, and testing at any pressure higher than that is a moot point. Well that's only about .45" HG. However, flow testing at a higher pressure is required, to simulate all conditions the carb will see on the engine.