trouble with dominators

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chevy art
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trouble with dominators

Post by chevy art » Tue Jun 05, 2018 8:30 pm

one friend has a 502 bb ford with aluminum heads and makes power to aprox 65oo and other friend has a 383 sbc with big alum heads abd big solid roller and can probably go to 7500-8000 rpms. both had the 1050s sent out to some guru and the carbs camd back as follows m 502 carb is 92 square now with no power valve and the 383 carb if 90 square with no power valves. i believe factore specs are 88 jets front and rear and 4,5 PV in front and rear. both of these carbs turn the plugs in both engines black and sooty and gas just flows driving around and even over 4000 rpms. both engines are plumbed for niitrous the 383 has individual nitrous line to each cylinder runner on intake and a plate is on the 502 ford. dont know what else the carb guy did to these carbs. as far as i am concerned each carb should have been within 1 jet size to run great right out of the box without the juice. any ideas what could be going wrong with these carbs other than the fact that they are probably too big for each engine. thanks for help art

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Re: trouble with dominators

Post by NormS » Tue Jun 05, 2018 8:48 pm

Art, Which model(s) of Dominators do you have? It could be that the calibration that the modifier put into these carbs, was intentionally rich, in an attempt to keep the engines alive when using the nitrous. Of course , the nitrous systems should be self sufficient with the fuel that is injected simultaneously with the nitrous, and should not require any changes in carb calibration.
I'm assuming that your fuel pressure, float levels, and idle mixture were adjusted after you put the carbs on. Is that correct?
It appears that at least the low speed circuits are very rich. This can be caused by high float levels, idle mixture set too rich, and butterflies too far open at idle.
Last edited by NormS on Tue Jun 05, 2018 8:52 pm, edited 1 time in total.
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Re: trouble with dominators

Post by cgarb » Tue Jun 05, 2018 8:52 pm

So a BBF and a SBC should have the same carb set up? I think not...even still sounds like there are problems elsewhere. If they have gas pouring in just idling and driving around sounds like needle and seat problems to me. Either dirt or fuel pressure pushing past the seat...can be caused by many things, too much fuel pressure, a bad float, floats not set properly...ect. I would have them call the carb company back and tell them what's going on and see what they suggest. If they are a decent company they should work with them to get their problems taken care of.

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Re: trouble with dominators

Post by superpursuit » Tue Jun 05, 2018 10:26 pm

It's power valves and power valve channel restrictors that control fuel for WOT. Main jets are supposed to be for high speed cruising. Only drag racers use jets for WOT mixture as they are the only ones not using part throttle. So when these cars are cruising [from your post it sounds like they are street cars] they actually have WOT mixtures which is far too rich for cruising or part throttle. Whoever set up these carbs should have been told what the intended use was. I hope this helps.

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Re: trouble with dominators

Post by Walter R. Malik » Tue Jun 05, 2018 10:28 pm

chevy art wrote:
Tue Jun 05, 2018 8:30 pm
one friend has a 502 bb ford with aluminum heads and makes power to aprox 65oo and other friend has a 383 sbc with big alum heads abd big solid roller and can probably go to 7500-8000 rpms. both had the 1050s sent out to some guru and the carbs camd back as follows m 502 carb is 92 square now with no power valve and the 383 carb if 90 square with no power valves. i believe factore specs are 88 jets front and rear and 4,5 PV in front and rear. both of these carbs turn the plugs in both engines black and sooty and gas just flows driving around and even over 4000 rpms. both engines are plumbed for niitrous the 383 has individual nitrous line to each cylinder runner on intake and a plate is on the 502 ford. dont know what else the carb guy did to these carbs. as far as i am concerned each carb should have been within 1 jet size to run great right out of the box without the juice. any ideas what could be going wrong with these carbs other than the fact that they are probably too big for each engine. thanks for help art
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Re: trouble with dominators

Post by cjperformance » Tue Jun 05, 2018 11:06 pm

I see some fuel washed bores coming up ! If these engines are expected to cruise around between WOT runs then (short of a lot of rework) fit a power valve to at least the primaries (or if 1:1 throttle pri and sec) and rejet to suit or these engines WILL be damaged.
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Re: trouble with dominators

Post by chevy art » Tue Jun 05, 2018 11:20 pm

thanks guys these are both drag cars, but driven on the street to cruises., and you cant have the best of both worlds. these carbs were both set up for nitrous, so street driving is probably a big no-no. i agree with our member who said something is really wrong with the setups for cruising,but probably for track only racing with the juice. i still dont understand the part where there are no power valves in either carb and this is probably one of the problems. i always myself use the correct power vale in my race carb(front only) and correct size according to vacuum is used, this is for just navigating in the pits without loading up. both these carb have PVs removed but they are not 8 jets sizes bigger to take the place of the PVs. this is the part i dont understand. i would think these carbs would be lean without upsizing the jets. any more suggestions thanks art in NY

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Re: trouble with dominators

Post by cgarb » Tue Jun 05, 2018 11:36 pm

With no power valve they should be jetted square...ex. 86 front 86 rear...how are these set up?

Nevermind that, I just saw they are square...that's how they should be with no PV. I've ran race carbs with no PV without issue before. At idle, the PV is closed anyway, the idle circuit is what the car is running on so that shouldn't be an issue except for part throttle driving. You could always try adding the powervalve and jetting down 8 in the front and see what that does. Wouldn't hurt a thing.

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Re: trouble with dominators

Post by andyf » Wed Jun 06, 2018 12:14 am

As long as the carb guy didn't drill out any passages the carbs should be able to be fixed. If it was me I'd put a PV in the front and pull a bunch of jet out. If the carbs have billet metering blocks then they can be dialed in pretty close using just a screwdriver and a wide band.
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Re: trouble with dominators

Post by chevy art » Wed Jun 06, 2018 12:36 am

hey cgarb they are square, but the jet sizes are way down, definitely not up 6-8 sizes due to the power valve removal. should be lean, not rich, the way they are now. thanks atr

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Re: trouble with dominators

Post by cjperformance » Wed Jun 06, 2018 6:12 am

chevy art wrote:
Wed Jun 06, 2018 12:36 am
hey cgarb they are square, but the jet sizes are way down, definitely not up 6-8 sizes due to the power valve removal. should be lean, not rich, the way they are now. thanks atr
Possibly check for air bleed or emulsion changes.
Craig.

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Re: trouble with dominators

Post by Walter R. Malik » Wed Jun 06, 2018 12:03 pm

You never did say whether or not these were 3 circuit or 2 circuit Dominator carbs. That alone will make a huge difference.
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Re: trouble with dominators

Post by mag2555 » Wed Jun 06, 2018 12:24 pm

First off are these 2 circuit or 3 circuit 1050 models?

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Re: trouble with dominators

Post by chevy art » Wed Jun 06, 2018 6:48 pm

i dont know if they are 2 or 3 circuit dominators. i will have to as my friend what the holley part number is and that would be the best way for you guys to help us . thanks talk soon im use to doing my own 4150 (old school) holleys. all this new stuff is way over my head. really appreciate the time you guys put in to help me and my friends art in NY

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Re: trouble with dominators

Post by mag2555 » Thu Jun 07, 2018 6:17 am

What's the carb number stamping on them?

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