Dominator tuning questions
#1802300
04/13/15 11:48 AM
04/13/15 11:48 AM
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Joined: Mar 2008
Posts: 202 Barboursville, VA
belvedere383
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Barboursville, VA
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I recently changed the camshaft and the carb on my engine (496 low deck, 12-1 compression, indy R2 camshaft)
It is hard to start, you have to hold the throttle wide open, as well as it won't idle at anything under 2000 or it trys to bog down and eventually dies. It absolutely wont idle in gear.
It has an out of the box 1050 ultra dominator with 3 circuit metering. I believe it has 5.5 pv front and back with 78 primary jets and 84 secondarys. Fuel pressure is 6.5-7 psi.
It rev very crisp after idle fwiw.
Any help would be appreciated as this is my first experience with a 3 circuit style carb.
65' Belvedere
496'' Stroker Indy Heads
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Re: Dominator tuning questions
[Re: ajcasini]
#1802316
04/13/15 12:26 PM
04/13/15 12:26 PM
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Joined: Mar 2008
Posts: 202 Barboursville, VA
belvedere383
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The idle mixture screws are all 1 1/2 turns now. So I will proceed to check for vacuum leaks and block those power valves off.
Thanks
65' Belvedere
496'' Stroker Indy Heads
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Re: Dominator tuning questions
[Re: BradH]
#1802365
04/13/15 01:33 PM
04/13/15 01:33 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
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I Live Here
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Surprised Dom hasn't jumped in on this thread, yet. Dom doesn't care to make 3 circuit carbs work and convert em all to 2 with excellent results including 2 8 second cars. Aj will hook ya up as he's helped me bunches.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Dominator tuning questions
[Re: Thumperdart]
#1802432
04/13/15 02:54 PM
04/13/15 02:54 PM
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Joined: Mar 2008
Posts: 202 Barboursville, VA
belvedere383
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning?
65' Belvedere
496'' Stroker Indy Heads
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Re: Dominator tuning questions
[Re: belvedere383]
#1802451
04/13/15 03:31 PM
04/13/15 03:31 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
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I Live Here
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? It's deeper than that but yes that's one of the reasons for me personally.................And what Mark said.
Last edited by Thumperdart; 04/14/15 03:15 PM.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Dominator tuning questions
[Re: belvedere383]
#1802550
04/13/15 06:27 PM
04/13/15 06:27 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
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I Win
Joined: Jan 2003
Posts: 32,394
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? it just aids the guys who can't tune a 3 circuit..
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Re: Dominator tuning questions
[Re: Quicktree]
#1802554
04/13/15 06:31 PM
04/13/15 06:31 PM
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Joined: Mar 2008
Posts: 202 Barboursville, VA
belvedere383
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I am thinking that there is too little vacuum at idle and it is allowing the PV to open while idling, but I could be wrong i'm gonna switch to the block offs and check how that works along with going over the whole engine for vacuum leaks.
Also this carb is brand new out of the box, I put it on when I switched the cam.
Last edited by belvedere383; 04/13/15 06:32 PM.
65' Belvedere
496'' Stroker Indy Heads
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Re: Dominator tuning questions
[Re: Quicktree]
#1802567
04/13/15 06:46 PM
04/13/15 06:46 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
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I Live Here
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? it just aids the guys who can't tune a 3 circuit.. Too funny right there and thankxx 4 your support........
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Dominator tuning questions
[Re: Thumperdart]
#1802569
04/13/15 06:49 PM
04/13/15 06:49 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? it just aids the guys who can't tune a 3 circuit.. Too funny right there and thankxx 4 your support........ hell I read it backwards anyway. lol
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Re: Dominator tuning questions
[Re: belvedere383]
#1802575
04/13/15 06:55 PM
04/13/15 06:55 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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I am thinking that there is too little vacuum at idle and it is allowing the PV to open while idling, but I could be wrong i'm gonna switch to the block offs and check how that works along with going over the whole engine for vacuum leaks.
Also this carb is brand new out of the box, I put it on when I switched the cam. Like was said already.. plug the PV till you get it running right then put in the PV and reduce the pri jetting 7 sizes.. make sure your timing is set first
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Re: Dominator tuning questions
[Re: belvedere383]
#1802590
04/13/15 07:22 PM
04/13/15 07:22 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
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I Win
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? don't you mean from a 3 to a 2?
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Re: Dominator tuning questions
[Re: AndyF]
#1802754
04/13/15 10:26 PM
04/13/15 10:26 PM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
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master
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A shed in England
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Dominators are easy to provide idle bypass air. You can drill and tap holes on the top of the carb that will let air into the manifold via some small jets. The new gen 3 Dominators have something similar
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Dominator tuning questions
[Re: Quicktree]
#1802870
04/13/15 11:39 PM
04/13/15 11:39 PM
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Joined: Dec 2014
Posts: 304 Florida
Mark Whitener
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Are the gains from switching from a 2 circuit to a 3 circuit strictly ease of tuning? it just aids the guys who can't tune a 3 circuit.. Has nothing to do with being able to tune it. Has to do with a couple different issues with the factory style 3 circuit metering blocks. One is the inability to lower the idle feed restriction. Early 3 circuit Dominators had the idle feed tube pinched at the bottom, this was your idle feed restrictor. However it made tuning it impossible without pulling the tubes. Later Dominators use an open tube and made the restriction at the top, above fuel level. This is not as stable for fuel delivery as discussed in the link below. Next is the obstruction the idle feed tube becomes when either higher HP or combination of higher HP and oxygenated fuels are used, you can reach a point where adding more main jet has no effect. Some companies throw a bunch of intermediate fuel to compensate, that is a bad way to do it. You get more liquid fuel, and it will usually negatively impact distribution. You can open up the main wells, but that means pulling the tubes out. And last is the need to even have intermediate fuel. If you tune it correctly the need for intermediate fuel goes away for most applications. It's like having dirt hauled in to fill a hole you don't have. You end up with more fuel than you need and that can foul plugs. I use two types of metering blocks, BLP 5124 2 circuit or 5120 3 circuit wide body blocks for gas. I will almost always plug the intermediate circuit on the wide body blocks, I use them sometimes because I can control the size of the kill bleed. For methanol I use a methanol version of the wide body block, and will use a little from the intermediate circuit only to supplement the mains if needed. http://racingfuelsystems.myfunforum.org/viewtopic.php?f=25&t=18
Last edited by Mark Whitener; 04/13/15 11:41 PM.
Mark Whitener [url=www.racingfuelsystems.com[/url]
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