Holley Blue pump and regulator.

Maybe. I went pretty fast on motor with a stock fuel pump. I think Lou has too.

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Official Cookie and Mater Tormentor.

Hey Zilla,
Is your carb a #4776 1850 double pumper?
What exactly are "annualar" venturies and do they come on all holley 600 double pumpers new and old? I am looking at a couple on E-bay and want to make sure I have my head screwed on

A #4776 is a 600cfm double pumper
A #1850 is a 600cfm vacuum secondary

There are several different types of Holley boosters. An annular booster has several small fuel feed holes arranged in a circle in the middle of the booster, most other boosters have one large discharge port. The theory is the smaller holes help atomize the fuel. It seems to help in WOT conditions but at a cost of part throttle power do to the anular booster needing more signal strength than whats available to flow fuel. Motor combo, usually a race type is best, plays a big part in how well an annular booster performs.

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Slant Cecil

I like mine too...









Here's a comparison of the stock booster as taken out of the 600, and the installed annular venturi combo(upper left corner)... This decreases the total CFM flowable on the carb (this 600 is closer to 570...), but as compared to the stock Holley 390 on the street it had better response, fuel metering seemed to be better, and since my car would like to have a bit more carb than 390, it seemed to have a bit more power since it could breathe at WOT (but had to use a stiffer spring so the secondaries didn't just "flop" open and give me a nice "lean out/too rich" condition)

These boosters only work on the bigger bore throttle bodies, I tryed to have a 450 cfm Holley made with annular primaries and they don't fit (the carb was the right size, for my car, but the boosters don't fit as the bore holes are too restrictive. That carb now has a set of annular "drop leg/down leg" boosters that are less restrictive than the normal booster...I'll probably run that carb next summer when I have more time to dial in the fuel and timing...


FYI,

-D.Idiot

So, the annualar venturies are not stock units? Where do you get them and how much?

Holley might sell them, but I don't know zip about 4-barrels.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

The Holley annular booster produces the best (strongest) metering signal and provides the best atomization of all the factory Holley boosters. Unless you are doing the work yourself they are not very economical to have installed in a carb that had different boosters. You also have to be prepared to do extensive fuel curve work to have it work well.

The Holley 4010/4011 series carbs have annular boosters so I have both a square bore 4010 series 750 cfm and a spread bore 4011 series 650 cfm. I also have a tricked up Q-Jet as they have good primary boosters and adjustable secondaries. Except for an initial hesitation (long intake runners/not enough pump shot we suspect) the Q-Jet was working pretty well on my friend Bob's 2.7L Corvair so I figure it will work on my slant. I just have to make an adapter for my Clifford intake since I only have a 2bbl adapter.

Certain Barry Grant Demon carbs have annular boosters. The 525 Road Demon and Road Demon Jr do on the primary side and the 575 Speed Demons are also listed as having annular boosters. There are others, but most are too big for a slant. The Barry Grant removable sleeve 2bbls meant for circle track look interesting. You can change the venturi sleeves, boosters, and play with the 5-emulsion hole billet metering blocks 'till the cows come home, but at $523 from Jeg's I'm not that interested. You can get a 625CFM 2bbl (equivalent to a 440cfm 4bbl) however.

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Joshua

Ok, I was looking in the carb pile at work and found an old motorcrap Holley 650 or something and it had the annualar venturies on the primary side and regular ones on the secondary side. I have never done much work with Holley carbs. And they have so many after market parts and names I am going to have to get privy with all the lingo. Thank you for all the help and understanding.

The most experienced carb guy I know said the Holleys that were used on medium/heavy duty trucks with governors came with annular boosters in the primaries. That could be what you've got. I wonder if they also came with 2 stage power valves? Anyhow, the primaries are what really count most of the time so that could be a good carb to work with. For me I'm going to try my worked over Q-Jet and if that doesn't fly I'll try my 4011 series Holley 650 spread bore or see about getting my 400 AFB or 390 Holley back.

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Joshua

I think you are right about it being a truck carb I some what remember it coming off a 5 ton chev. The base is gone but I think it had a governor on it, so it is just for parts. Now that I know what annualar venturies are and how good they work I will snag it and hoard it for myself.