2 circuit versus 3 circuit Dominators

Posted By: markz528

2 circuit versus 3 circuit Dominators - 10/02/13 11:58 PM

How much of an advantage do 3 circuit Dominators have over 2 circuit Dominators is a drag car? The car in question is my Coronet that makes around 800 hp and runs 9.60's.

Posted By: AndyF

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 12:17 AM

Subject that has been debated over the years. The 3 circuit should be better but they sometimes require a ton of tuning to get the intermediate circuit working correctly in the car. The intermediate circuit is very sensitive to part throttle (super rich at part throttle) so it depends on how you leave the line. If you hold the engine at part throttle against the brake then a three circuit probably won't work for you.

Best deal is to call a carb shop and discuss it. I went back to a two circuit 1250 on my 514 engine. The guys at BLP told me the two circuit is adequate up to about 900 hp and then you need the third circuit, but it really depends on the application.

Posted By: markz528

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 12:45 AM

That makes a lot of sense. I have a 3 circuit now that I believe is not set up right. My buddy has a 1050 Dominator 2 circuit for sale from a roundy round car (too big for them) at a reasonable price and I was wondering if I should try it. Sounds like it may be a good idea. I'm sure I could borrow it without committing to buy it.

Currently I'm leaving on the brake at 3500 rpm with the pedal to the floor. I have been leaving around 4500 rpm in the past.

Posted By: sixpackgut

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 02:01 AM

I thought the 3 circuit helped cars on the brake with pedal to the floor because air isn't moving fast enough past the boosters

Posted By: AndyF

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 03:21 AM

If you can borrow the 2 circuit then give it a try. If it is setup up close for your combination it might just work.

You can also make some changes to your 3 circuit. It is best to have a wide band to set up a 3 circuit but you can do it old school also. One easy thing to try is to remove the intermediate air bleeds and see how it runs. Holley left the air bleeds out on some 3 circuit carbs. You can also reduce the jet size on the intermediate circuit just to see how it works. Every 3 circuit that I've ever worked on was dead rich in the intermediate circuit and needed to be leaned out a ton.

Posted By: Cab_Burge

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 04:18 AM

Quote:

If you can borrow the 2 circuit then give it a try. If it is setup up close for your combination it might just work.

You can also make some changes to your 3 circuit. It is best to have a wide band to set up a 3 circuit but you can do it old school also. One easy thing to try is to remove the intermediate air bleeds and see how it runs. Holley left the air bleeds out on some 3 circuit carbs. You can also reduce the jet size on the intermediate circuit just to see how it works. Every 3 circuit that I've ever worked on was dead rich in the intermediate circuit and needed to be leaned out a ton.

Posted By: markz528

Re: 2 circuit versus 3 circuit Dominators - 10/03/13 12:20 PM

Quote:

If you can borrow the 2 circuit then give it a try. If it is setup up close for your combination it might just work.

You can also make some changes to your 3 circuit. It is best to have a wide band to set up a 3 circuit but you can do it old school also. One easy thing to try is to remove the intermediate air bleeds and see how it runs. Holley left the air bleeds out on some 3 circuit carbs. You can also reduce the jet size on the intermediate circuit just to see how it works. Every 3 circuit that I've ever worked on was dead rich in the intermediate circuit and needed to be leaned out a ton.

That is exactly what I was thinking. In the process of installing the new Racepak data logger so I will have air fuel ratio monitoring next time out.

With the 80 intermediate air bleeds in the carb now I think I am WAY rich and that is why the car works so much better on the launch as the weather gets cooler.

Posted By: 82ramIndy493

Re: 2 circuit versus 3 circuit Dominators - 10/04/13 01:59 AM

Call Jesse at Bigs Performance. He can do the conversion from 3 to 2 cuircuit. He just did mine last year and I am satisfied with it and didn't see any loss of time with it. He can tell you if it will help or hurt you.