Motorsports Village

Two Circuit Holley Dominator Conversion
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Author:  Administrator [ Tue Feb 05, 2008 9:28 am ]
Post subject:  Two Circuit Holley Dominator Conversion

This thread will deal with the process of converting a 3 circuit Holley Dominator carb to a 2 circuit carb.  There is another thread on this that lists the procedure required to get help. Please read this post BEFORE you go posting questions on the board! ... f=6&t=9717

There are several reasons for doing this that are outlined by a post started by PSweeney located here. ... php?t=3283

This thread will only deal with the carb mods and no other discussion will be allowed.  Any post that is not on topic will be deleted or edited so make sure any questions or comments you have are about the 2 circuit Dominator carb mod only!

Author:  Ken0069 [ Tue Feb 05, 2008 9:45 am ]
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There are three members here that have done this mod.  Slowpoke, Scott Smith and I have done it.  It’s not hard but it does require some attention to detail.  The main thing is that if there’s a question in your mind about what you are doing, STOP and read over these posts again to see if that question can be answered!  If that doesn't answer it, then do a search in this section to see if you can find an answer. If not, then post a question on the broad!  

The first and most important step is to “map” the carb before you start, ie, gauge ALL the relevant holes and such so you know where you are starting from. Once “Mapping” is done (and make sure to write it down!), there is a list of items that you will need to complete this process in another thread that you can see here in the second post down the page. ... f=6&t=9717

While we can help with certain things, we can’t give each of you a specific tuneup that will work well right off the bat.  As you will see from reading through this and other threads, usually no two engines will be exactly alike. What you will get though is a starting point that is usually reasonably close that you can work from.

I’ll try to get some photos of my carb in the next few days to post here and help identify areas that need to be modified.  

So, let’s get started!

Author:  PSweeney [ Tue Feb 05, 2008 11:51 am ]
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Ken, in the interest of uniform terminology and to cut time sourcing the bits (and failing) in the UK etc, I've placed an order on McMaster for the bits Scott mentioned. Their site and range of products is fantastic. I'll be a little behind you guys till the kit is with me but please carry on with the thread.

First question I think worth posing is, what is the Holley Pt No for a suitable Holley 4150 metering block ?

Author:  Ken0069 [ Tue Feb 05, 2008 1:03 pm ]
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Phil the metering blocks I used from my junk box were #33102 but mainwell plug position and type is most important.  Seems there are two different plugs.  One type has the mainwell plug solid and flush with the top of the block while the other uses a cup plug that is down the mainwell hole a bit.  The ones with the primary mainwell cup plug down the hole are a good choice and that's what I have. Make sure that whatever you use has idle screws in'em though.   ;-)

Right block.


Wrong block.


Author:  PSweeney [ Tue Feb 05, 2008 5:07 pm ]
Post subject: 

thanks Ken, well doing a little digging, the 3310-2 you used is listed as a 4160 750cfm VS ? ... isting.pdf

Author:  Scott Smith [ Tue Feb 05, 2008 5:17 pm ]
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If your not on a tight budget I would recommend the billet blocks. They are available from several vendors like BLP, AED, and APD.
And they look really purty.  :-$

Author:  oobob [ Tue Feb 05, 2008 6:51 pm ]
Post subject: 

I have an 1150 that i've thought about converting, the main body already has t-slot jets and 12 hole billet boosters also have some 2 circuit billet blocks laying here, the billet blocks have 4 threaded elmulsion holes and the inner 2 plugs in the top are recessed cup type about 9/16" down into the block, the idle jet holes are not tapped.
Will these work?
Scott could you post some pics. of your completed bolaws 2 circuit blocks?


Author:  Ken0069 [ Tue Feb 05, 2008 7:21 pm ]
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It's not absolutely necessary to drill and tap the idle jet holes unless they are TOO large to begin with.  Mine weren't so there was no drill and tap there.

Emulsion/air bleeds.  In mine, I only have one open in each channel, not counting the kill bleed in the crosswell.  The others were plugged with lead shot.  I'll have to take the metering block out to see which one I left open as I don't remember now.  Ya have to be careful with emulsion.  Too much of a good thing isn't good at all.  Too many sources for air to get into the metering system will result in those air bubbles combining and causing the fuel to start "slugging" at the boosters like air from a garden hose!

Author:  Scott Smith [ Tue Feb 05, 2008 9:42 pm ]
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Ken on mine tuner had one emulsion hole above float level and one below.

On the idle jet, it needs to be moved from the top to the bottom.

I don't have a picture of the completed 2 circuit block because I was too impatient to get it running.

Author:  Beretta [ Wed Feb 06, 2008 7:00 am ]
Post subject: 

If I was to order Billit  metering blocks for my 8896 what part # should I order for race gas??? I have ordered from Quick fuel in the past so here's there link...

Author:  oobob [ Wed Feb 06, 2008 7:04 am ]
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Scott, I looked thru all 185 photos which include some nice stuff i might add. Photo #158 shows a main body with the billet boosters like mine, is this the carb you converted to a 2 circuit ?
On another site you had stated  the idle, part throttle and going up on the converter was crisp & clean, Have you gotten a chance to see where your wide open AFR is yet ?


Author:  Scott Smith [ Wed Feb 06, 2008 7:22 am ]
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Beretta wrote:
If I was to order Billit  metering blocks for my 8896 what part # should I order for race gas??? I have ordered from Quick fuel in the past so here's there link...

In BLP it's a 5124

Just so you know that part number is a machined billet block period.
You need to tell them if you want the brass plugs for the main well, Idle screws, gaskets etc.

Author:  Beretta [ Wed Feb 06, 2008 7:26 am ]
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Thats  3 circut?? Can all the jets/bleeds  be gotten from them??

Author:  Beretta [ Wed Feb 06, 2008 7:27 am ]
Post subject: 

what's the visual difference between the two?

Author:  oobob [ Wed Feb 06, 2008 7:49 am ]
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Barry, The quickfuel 34-5 are the ones i have and hope will work, if you plug part of them off anyway it shouldn't make much difference. I'm  hoping to only have to tap for idle jets, drill the booster feeds and plug a couple emulsion holes.
That would probably be too easy though   #-o


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