S10xGN

iTrader: (11)

Hey All,

I'm needing to pick a carb for my swap. Right now, it's a stock '03 Corvette 350 HP motor with 1 3/4" longtubes, Victor JR manifold and MSD-6010 box (I'll prolly switch cams to something a bit more radical before running it in this form). The car is a Maverick with a 3.50:1 locker, 200R4 trans and PI Vig 3600 stall single disc L/U. Should weigh around 2800.

My thoughts are a 750 Holley with mechanical secondaries. I'm having trouble finding one with annular boosters (which I think will be better on the street) that won't kill my wallet. What are your thoughts?

Russ

sbmalibu

check out a 750 4150 race series carb hly-0-9379 from summit racing. Its a annular discharge 750 with no choke assembly. I have the 830 version on my car now and like it a lot though i think its a little big for my 355 small block

chris-m

i'm on a demon 750cfm mech secondary carb, worked well.

Shawn MacAnanny

iTrader: (12)

I have a holley HP750 vacuum secondaries. 72 primaries, 76 secondaries, 6.5 power valve, and im installing a 50cc acclerater pump to get rid of the off idle stumble.

cowfarmer

I also have the Holley HP750 vacuum secondary 0-82750

SMAX

iTrader: (11)

I am running a speed demon 750 mechanical secondary and it is very crisp. If you go with a holley I would look at the 750hp and in the demons I would look at the 750 speed demon because they are better suited for a street strip car than the mighty demons.

forcd ind

iTrader: (7)

i wouldnt think you need an. boosters, downleg should work fine-one thing i had to do to mine, was to go with a really agressive pump cam, (i think i used the green one) it needed a bigger off idle shot, it sure didnt feel like a fuel prob., dumb luck led me to the problem-i wonder if others found they needed more pump off idle
mine is an lq4, z06 cam, d1sc procharger-even w/o the supercharger hooked up, same problem-i figured the vic jr intake needed a better signal
i think a 750 would do you fine

S10xGN

iTrader: (11)

Love the look of the Demon's but have heard rumors of dubious quality control as of late. They do make exactly what I was initially looking for though (132-5402020GC)... I like the milling of the choke horn, I'd never need a choke in my (Gulf Coast) location and the step up to a Mighty Demon is less than $50.00. I looked at both the Holleys, still can't find one with a milled choke and annular boosters. The '9379 looks OK, but the tech sheet says it will not work with an auto OD trans (even though the pic shows the correct linkage). Go figure! I had planned on fabbing something up anyways.

How exactly are the annular's different than the downlegs as far as street driving? I would think the transition from idle to mains would be a bit better with the annular's? Are the QC issues anything that can't be overcome by a thorough inspection before use?

Thanks!

Russ

SMAX

iTrader: (11)

There were instances where metal shavings were found in the fuel bowls, but it isn't that difficult to pull the bowls off to inspect. If you go with a might demon I would go with a 650. You are running a stock engine and the mighty demons are for engines with 240* duration cams or larger.

ws6t3rror

iTrader: (3)

Aed 750 ho series, or call them up and ask what they think.

I have lately been using *****'s though since he is local to me and I can get him to personally dyno tune the stuff. But he will put a hurting on your wallet to the tune of $800+ for a carb.

The aed stuff doesnt cost much over a nice stock demon or holley and runs one hell of a lot better. When I was using them I would rarely even have to make a jet change, beautiful fuel curve.

rojs234

iTrader: (5)

Click on the thumbnail below to enlarge it and you can see the difference between a 750 downleg and a 750 with annular boosters BG#5423020GC. I got the dyno sheet from the Aug. 2005 issue of Car Craft. The engine was a LS1 with GM ported heads, GM single plane intake and Crane 222x234 cam. Low and mid-range was impressive, which I would think would be an advantage on a street car or a drag car with auto trans. BG also makes a Speed Demon with the annular boosters #1402020, I think. I would call Holley and ask WHY?? the #09379 wouldn't work on auto trans car. I have about the same drivetrain set-up as you except Vig 3000 and 4.10 gears. I also am going with an annular booster carb as soon as I can afford it. I think it will really help with my L92 heads and the huge plenum on the GM single plane.

Shawn MacAnanny

iTrader: (12)

So i know this is gonna sound dumb but what is an anular booster? I mean how does it differ from a downleg? I'm semi new to carbs and just rebuilt my 2nd one haha. I'm always looking for that extra few hp.

lowdeuce

I would check into Pro Sytems Carbs. You will spend the same amount of money on a custom carb as you will on a Holley HP carb.

Jared

rojs234

iTrader: (5)

You can't be any worse than I am. But, since I'm not smart enough to explain it, even though I understand it, I don't think BG would mind if I put it pretty much in their words. " Finally, there is the annular booster, which is slightly larger in diameter than the downleg and employs a series of small discharge holes drilled into the inside circumference of the booster to improve fuel atomization. This annular design accomplishes several things. At lower engine speeds, slow air speed creates a weak signal ,which reduces the amount of fuel moving through the booster. An annular discharge boosters multiple holes offer many points for the fuel to enter the venturi as opposed to a single discharge point. At lower air speeds this offers measurable advantages, especially when combined with the annulars better signal strength. This is important for situations where large-volume carburetors are used in conjunction with a long-duration camshaft. With a weak manifold-vacuum signal at idle, annular-discharge boosters can greatly improve throttle response and drivability." Whew!! What he said !!!

S10xGN

iTrader: (11)

Thanks for the graph. So you're running a 200R4? What carb are you running now and what type of TV cable did you end up with? I've pretty well decided to go with the BG5402020GC carb, and I already have the Lokar cable setup. The BG looks like it has the underslung linkage to operate the TV cable, but then again, so did the Holley...

Russ

Qwiknotch

I would buy an HP750 right out of the box and just jet it for what you need.

Oscar Will

In my humble opinion, for the street I'd use a vac. secondary carb. I never saw much of an advantage using mechanical secondaries when street driven. But then, I'm old.

S10xGN

iTrader: (11)

Just got a super deal on one from a member here, has the downleg boosters, but for the price...

Russ

rojs234

iTrader: (5)

You're welcome. I wish I could have included the whole article. I think it would have definately convinced you that the BG carb you picked is probably the right choice. I think the Holley #0-9379 would have also been a good choice. I am running an Edelbrock #1407 750 right now because I happened to have one. To be honest, it works quite well, especially with street tires. It is kind'a lazy when you first stab it (from a roll) which helps the tires start to get a hold, but when the secondaries start to open, it's sit down, shut up and hang on!! With any kind of tire that would hold, even a drag radial, the double pumper you chose would be much better. The BG or Holley would be much easier to tune the accelerator pump system, which, in my opinion is a necessity on a large plenum single plane intake. To your other question, yes I do run a 200R4, and I like it very much. The tranny is slightly smaller in size which was a benefit in my case and in my opinion the gear ratios are much better suited, especially if you are running lower gears, in my case 4.10's. It also has a higher overdrive ratio, which puts you back in good shape on the highway. I am running the Lokar stainless TV cable with a small piece of linkage from Bowtie Overdrives that lets you adjust the travel so you get full travel on the TV valve. THIS IS SOMETHING THAT HAS TO BE RIGHT!!! There are several sponsors on here that probably have similar products. There are also several other members on here that run 200R4's that can tell you more about them than I can. Good luck on the Maverick. It should be a killer on the street or strip. One more thing. If you can't find the linkage you need from a sponsor, Bowtie Overdrives has a linkage kit made specifically for the Demon carburetors.

bada

HP 750 no doubt. Vacuum secondaries for the street. I have run the HP mechanical secondaries & the vacuum secondaries back to back at the track. And could only see around .005 difference in ET. The vacuum is much better on the street. I have also tried the demon carbs, and did not care for them much. I have had very good luck with the HP.