well guys i some schoolin on the big 4500 carbs...i hear the 2 circutand 3 circut stuff and have no idea of what they are...i am looking to pick 1 up soon for my 451 motor i got a few weeks back...and would like to know whats the best 1 to go with ...
451,-1 heads,713 lift roller,looking to put a 2 1/8 header on it..let me know if you need anymore info..lol

www.bigsperformance.com or call 1-715-835-3726 and ask for Jesse!!!!

Is this a trans brake or no trans brake application? I was told by Holley that the three circuit carbs are for trans brake cars,not for foot brake cars I have both and I had to change the intermediate bleeds on the three circuit carb. to make it work good in my car foot braking it. That was the reason I called Holley tech. to ask for there help on getting that carb to work better on my car, I was suprised when they told me that was the wrong carb .Like all things, if you want to make it work you can AndyF had a swinging deal in the race parts on a Holley ultra Dominator for sale, not sure if it is still available They do work well, I have always pick up ET and MPH when switching from a 4150 carb to a 1050 CFM or bigger Dominator carb.

thanks mike and cab .. the car is going to be foot brake also cab...

i tried the 1050 dom 2 circ and 3 circut on my roadrunner foot brakin and could see no dif,but they were OTB no mods.mabey with some tuning there would have been a diff.

I have always heard and believed that the 3 circuit carbs were for transbrake cars. And my personal experience has been that if you need the 3rd circuit, then there is no suitable substitute for it.

But if you don't need it, then it will cause issues. Not the least of the issues is a 3 circuit's tendency to load the engine up when returning to the pits and when staging.

It would be nice if you could test one or the other sometime. Or you can have one of the pros put you one together. (expensive!)

As a foot braker you will most likely want the 2 circuit.

The extra intermediate circuit on the 3 circuit carbs is there to help during accleration, but it is a super sensitive circuit. The dump tube design can really flood the engine with fuel at part throttle.

I've been using 3 circuit carbs now for a while in the dyno room but we lean the intermediate circuit out a bunch. Sometimes we reduce the jet area by up to 80% from the stock setting.

I'd probably recommend a 2 circuit Dominator for most guys. Nothing wrong with the 3 circuit design, but if you aren't set up with a wide band in the car, you can easily get lost trying to tune it.

i used the 1050 2 circut on my 528 ci. and run it both ways,foot and brake. works perfect either way. got a good deal on it also.

Wow...I always thought the 3 circuit was better for street driving Our's is a 1200cfm, 3 cct from Pro Systems set up for my combo. It had good AFR's as delivered, needed only a little more pump shot when we added a spacer this year. (Took us 'till the end of the season to realise it though )
Sorry to Hi-jack but you learn something every day.

Any good books out there that explain how a dominator works/modify

Street driving is probably not a good fit for a 3 circuit Dominator. A lot of street driving happens at part throttle and the intermediate circuit is really sensitive to part throttle operation.

Most of the three circuit carbs run super rich at part throttle. 10:1 AF is common or even richer.

If your carb was built for street driving then the carb builder might have just leaned the intermediate circuit way down. Most of the Holley carbs will be super rich at part throttle right out of the box. They aren't designed for freeway driving.

Well FWIW I have been using three circuit carbs on everything we do for a few years with no issue. Yes the intermediate circuit will need some tweaking for sure but having a more tuneable piece is what I want. Just my

Dwayne Porter years ago had a thread about tuning these on the street. I was having "Part Throttle Blue" with my 8896 3 circuit carb too.
I ended up drilling the main body Under the metering blocks and tapping the hole counter sinking it and added a common Holley jet. One could use air bleed jets too.
Worked slick as snot.

Yes, that is a good trick for the older carbs which do not have billet metering blocks.

The newer carbs come with billet metering blocks which are drilled and tapped for jets in both the intermediate circuit as well as the idle circuit.

call prosystems. best carb i ever had. gave them all my specs, carb was spot on out of the box. only change i had to make was to open up the idle air bleeds a few sizes. picked up 2/10ths. on cold start up, idles on it's own after 10secs. 440sb, street/strip, best et 9.61. 10.5 mpg. stay safe, seeya.

Not to hijack, but while we're schoolin' on dommi's what about the secondary linkage...progressive/soft progressive? Still interested in the 3 or 2 circuit differences. Bring it all on!