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Two Circuit Holley Dominator Conversion
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Author:  jmarkaudio [ Sat Jul 23, 2011 9:55 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

As long as the transition slot exposure is at around .020, I usually find the transition circuit is real close if the idle mixture screws end up between 1 and 1 1/2 turns out. When adjusting the idle jet and idle bleed you are setting them primarily for the operation of the transition circuit. Since the engine requires less fuel at idle you use the mixture screws to lean it further. On a transbrake equipped car it's not as critical if it's on the lean side on the transition circuit as long as it comes up clean, a street car or footbrake car you can be a little on the lean side with the transition circuit but not enough to surge or cause a stumble. I set idle with the least amount of turns for highest RPM and vacuum, don't worry about AFR. If you have a street car and are worried about mileage you might get away turning them in a little from there, again make sure it doesn't cause an off idle stumble. You won't be under enough load to hurt anything being a tad lean at lower speeds below the stall point of the converter. Remember to set everything to work at normal operating temps.

Author:  damned67 [ Sat Nov 05, 2011 4:28 am ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Hi All,
I'm finally setting a baseline tune on my 8896 Dominator with QF 34-105 metering blocks.
I've lengthened the t-slots, and installed t-slot jets/restrictors.
And I'm setting the metering blocks up with this baseline:

Start with a .040 IFR. Restrict the transition circuit to .0595 by installing drilled 10-32 set screws in the main body.
Enlarge the angle channel that feeds the main boosters to .159. Set the power valve channel restriction at .089.
Put .026" main air bleeds in it, and .078" idle air bleeds.
86 main jets in the front with a 6.5 power valve, and 93 in the rear without a power valve.

Now, before I go any further I just want to clarify that I remove the jet from the normal idle jet location, and tap and jet the lower location highlighted in the attached pic?

I know it seems pretty clear from Scott Smiths images earlier in this thread, but I just want to double check before I go making a mess of my pretty red metering blocks.
Oh, I should also add, for what it's worth, that my metering blocks are the version with 3 E holes per channel/side.

Cheers!
Image

Author:  Ken0069 [ Sat Nov 05, 2011 6:07 am ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

On the QF 34-105 metering blocks with only 3 E holes, I started out with a plug (blank setscrew) in #2 and #1 and #3 were open. At some point I switched the plug to #3 from #2 and that made a slight improvement in the AFR down track. Since all engines are different I'd go with 1 & 3 open to begin with and if you're recording AFRs you can play with those to see if you can make it better.

Oh, in case you haven't run across this in this thread, it wouldn't hurt to seal those brass plugs that are in top of both the mainwell and idlewell with epoxy. You don't have to pull them out, just fill them to where the epoxy will seal them off. It's been reported that they leak? I can't say that mine did but I sealed them anyway just to be sure.

Author:  shrinker [ Sat Nov 05, 2011 8:36 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Ken0069 wrote:
I'm sure that shrinker or jmarkaudio will answer on what problems not moving those is suppose to create.
The scientific tests of the location of the jet uses the terminology of the jet being submerged or not submerged. The results of a pure scientific test of the flow coefficient of submerging the jet compared to the jet being above the fuel level are that the submerged jet has a more consistent coefficient curve with less erratic behavior. The reason is that one of the factors of the flow coefficient through a orifice is the head available (head is the term used to describe the level of a liquid above an outlet). When you place the jet below the head of fluid the energy available for flow is greatest. When the jet is above the level, the energy available in the actual hole of the jet is less. This is simply because in the non submerged jet location the jet is located where there has to be a reduction of pressure in order to lift the fuel up to the jet. In simple words, you have to suck the fuel up to the height of the jet so therefor the jet must be in a reduced pressure zone. Reducing the pressure reduces the energy available so the jet has to function with reduced energy. WHENEVER you reduce the energy available to a certain system you increase the effect of inaccuracies and tolerances of manufacture etc. So a submerged jet has more accurate function than a jet located above the fuel level.

Now for how it is in a carby like a Holley. The IFR jet is located after the main jet so the pressure at the IFR location is not related to the fuel level in the bowl, its in fact related to the head in the main well. And you all now know how the head in the main well changes when you start fiddling with the emulsion and main jet sizes etc. So the real thing that affects the accuracy of the IFR in a non submerged system is the main well head. Because the main well level varies more than what the level in the bowl does the final result is that the submerged IFR is the better choice. However if your tuning techniques result in a larger main jet or a different main well head than other peoples techniques the jetting performance may have no difference during some conditions between the 2 ideas. When your thinking about this issue, its not a simple single factor problem, its an interaction issue.

Author:  themadreefer [ Mon Jan 09, 2012 2:38 pm ]
Post subject:  Re:

getting ready to make the 2 circuit conversion on my dominator. i have read this thread i know at least 100 times, hell maybe more.

just unsure what needs to be done with the the transfer slot feed on throttle body(in picture below). is this what is refered to as transfer slot jet? if so, am i to drill, tap and install adjustable bleed screw here,as my throttle body does not have a brass insert as pictured below?

thanks

Scott Smith wrote:
Had a chance to shoot some pictures.
Sure is hard to get them to turn out. I'm going to have to commender my wifes new camera.  =;

Transfer Slot jet or Transfer Slot Restricter.


http://bumracing.com/albums/SB2/TSJ2_001.sized.jpg

Author:  jmarkaudio [ Mon Jan 09, 2012 7:11 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Those are threaded in the picture and yes those are the t-slot jets. The early bodies will take an 8-32 brass set screw, the HP's take a 10-32.

Author:  Ken0069 [ Mon Jan 09, 2012 9:31 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Can't remember exactly what I used on my old style Dominator without looking but I believe it was a 10x32? If you do try to use an 8x32 make sure that the hole you put in that set screw isn't larger than the allen wrench used to put it in. I know that this can be a problem with some IABs as well so they are most always 10x32.

Author:  Tater [ Fri Jan 27, 2012 9:25 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Awesome Thread! I've probably read it about 20 times so far and it's starting to sink-in....lol
Newbie ?....
For a pre HP Dominator mainbody which will need the 8-32 brass set screws for the t-slot restriction. I found the brass set screws on McMaster-Carr. What length brass set screws are you guys using for the main bodies and the metering bodies for the idle feeds in the lower part of them? I'll be using a set of the Quick Fuel Tech 34-105's.

Thanks Tater

Author:  Beretta [ Fri Jan 27, 2012 9:57 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

6,8,10 32 1/4 long......

Author:  Ken0069 [ Fri Jan 27, 2012 10:10 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Tater wrote:
Awesome Thread! I've probably read it about 20 times so far and it's starting to sink-in....lol
Newbie ?....
For a pre HP Dominator mainbody which will need the 8-32 brass set screws for the t-slot restriction. I found the brass set screws on McMaster-Carr. What length brass set screws are you guys using for the main bodies and the metering bodies for the idle feeds in the lower part of them? I'll be using a set of the Quick Fuel Tech 34-105's.

Thanks Tater


8x32??? You better check the metering orifice size cuz I'm not sure you can drill an 8x32 out that large without cutting the allen wrench flats out?? :-k that and how large is the existing hole as some of those had a pressed in jet in that location. If memory serves, most of us used 10x32s in the TSJ locations. :-k But I could be wrong. ;-)

Author:  jmarkaudio [ Fri Jan 27, 2012 10:18 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

The 8-32 will go .063 or smaller with no issue. The one below and my 1150 both are 8-32.

Author:  Tater [ Fri Jan 27, 2012 10:51 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Beretta wrote:
6,8,10 32 1/4 long......

Thanks Man! Just trying to get all the ducks in a row before I go ordering stuff and discover when I get it that it won't work is all. I appreciate all your help thus far in this project of mine!!.... ;-)

Tater

Author:  Tater [ Fri Jan 27, 2012 11:05 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

Ken/Mark, I can't TY enough for this site! I've been reading and learning alot the past couple weeks along with taking down alot of notes. The more and more I read.....I can really relate to the function/calibration of the different circuits the more I want to try the set of early 750 Dommies compared to the run of mill pair of 450's that I have on the shelf for the next combo.

Where do you guys usually get the #61 - 80 drill bit sets? I did the E-Bay thing and came acrossed a few low $ sets.
I didn't see any micro drill bit sets on McMaster-Carr in the #61 - 80.

Tater

Author:  Ken0069 [ Fri Jan 27, 2012 11:19 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

I got mine from fleabay and I bought about 4 sets when I got them as you'll probably break a few before you get the "feel" for using them. If memory serves, I didn't pay but like 6 or so dollars a set for them.

Author:  jmarkaudio [ Fri Jan 27, 2012 11:22 pm ]
Post subject:  Re: Two Circuit Holley Dominator Conversion

8907A17, 31055A64, 2948A33, 2763A56, 8856A57, all from McMaster Carr starting at about $35 a set. You can get cheaper sets, I've found them at the local Ace hardware store in the welding section for about $13.

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