[quote="roadkill2"
"A Used Holley Carburetor is somebody else's mistake that they can't fix, so they sold it to you!"
95% of the time!
And I'd bet that goes pretty much for any other Carb off a race car . .[/quote]

Carbs are quite simple, and when they are calibrated and sized correctly they work as they were designed. It's when they are plundered by those that think they understand them that it becomes an issue. A fair amount of time the problem isn't even the carb, and even if it is most of the time it's not too tough to fix. A used Holley is a gem to someone that takes the time to understand it. Same goes for a Demon, nothing a little massaging won't fix.

Holleys are pretty simple pieces, but you just have to look for hammer marks, saw cuts, grind marks and all those little things that indicate that someone up the ownership line understood other ways of making one work . . then it's time for Burial rather than "massaging" . .

And true, carbs don't (often) wear out. Usually a carb gets blamed for something else that went wrong all of a sudden. Most of the time it's a 'Lectrical Gremlin . .

On a Holley, that's just about all that can "Wear" out, save for an occasional Needle and Seat . . or a disintegrating pump diaphragm . . Anything else is either contributable to dirt or human . .

I'm wanting to upgrade to a Dominator and I really like the looks of the new Holley Gen-3 Dominators! I know there are many good carbs on the market now days and ton of people who can upgrade and customize carbs. I also plan to go with an Edelbrock 2970 intake that has the cloverleaf plenum and I plan to clean-up the runners and plenum myself and use one of the HVH Cloverleaf Super-Sucker spacers.

When you buy any new carb, it's your's to do whatever you want to do with it. A used one? You don't really know.

But,if your carb's jetted right, and is working as designed, you seldom EVER have to mess with it. If your Jetting is right for where you live, then it'll work fine anywhere else. The more air, and the denser, the more fuel it will pull through the systems, so you shouldn't have to mess with anything except the idle circuit tuning . . If you do, then you have something else wrong with your tuning combination!

But again, that's only what all my past mentors have had to say about a Carburetor . . In the last 4 years, now, all my experience has been with the SV-1, so I'm no Holley Expert!

2-circuit
 

I think if you like the looks of the new gen 3, then that's what I would go for. If you have money to purchase it, then be prepared to spend a little more to have it customized if it needs it by someone that specializes in throttle stop carbs for the Super classes.

As part of my hobby of racing, I have been building engines, rear ends and carbs for years to support my cash flow needs for the racing. I buy good used brand name carbs, rebuild, do minor upgrades and then find racers who want them over new carbs because of price.

I have had about every brand of customized carb and a bunch of throttle stop carbs. It seems the throttle stop carbs all have a common theme, intermediate circuit leaning or elimination. I assume this is to accommodate the time on the stop and coming off the stop. They all seem to work great as bracket race carbs too. There may be more than just changing the intermediate air jet to make a good throttle stop carb.

I prefer to get 3 circuit carbs and then lean out the intermediate circuit, and perhaps have to richen the main jetting. 3 circuits also seem to have better resale value as most people don't realize a 3 circuit can be rich on the fuel curve.

In your case, the 2 circuit may be a good choice for throttle stop racing as mentioned in an above post by someone who knows a lot more than I do on this subject.

If you want to see the most exotic throttle stop carb, look on DaVinci's site at the SPIDER 1050 and 1250. He completely eliminated the intermediate circuit and them added HARLEY motorcycle custom jet pods above the main boosters to bring in the new intermediate circuit after the main circuit was already in, above 5000 RPM. It has jets in the pods to tune it for the throttle stop. I had one and it worked great. But it had external fuel hoses that I was a little uneasy about. Not sure if he makes them anymore. And they were $1895 new.

What carb are you currently running? If your stuck on the Gen 3 look, go with the 80902 2 circuit 1050.

I’m currently running a 1000 CFM, 4150 Race Demon (not sure it actually flows the rated 1000 CFM), which was built just before Barry Grant when out-of-business (maybe 2010). Additionally, I’m not running a throttle-stop, primarily foot-braking it and running it wide-open!

I’ve seen several posts with suggestions for different carbs (person preferences), however, I haven’t seen any compelling “technical criteria” exactly when you should run a 2-circuit, or 3-circuit carb.

2 circuit
 

Guys, correct me if I am wrong.

Originally the annular discharge, 3 circuit dominator like 9375 was designed as a tunnel ram 2X4 carb combination. 3rd circuit was to help cover up the flat spot on a tunnel ram with their big plenum volumes.

Then someone,(anybody know who?), found out the annular discharge boosters were better for some single 4 applications and the 3rd circuit just came along for the ride. Now all Dominators are Annular discharge but you get the choice of 2 or 3 circuit.

Don't really need the 3rd circuit on any BBC unless tunnel ram? Maybe still needed on SBC?