Motorsports Village

Holley Dominator Two Circuit Conversion Help Procedure
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Author:  Administrator [ Thu Nov 08, 2012 11:11 am ]
Post subject:  Holley Dominator Two Circuit Conversion Help Procedure

If you are planning to do a 2 circuit conversion and you think you will need help, then there's a bunch of stuff you need to do and understand BEFORE you start posting questions.

Keep in mind that this is all to help everyone learn as NONE of us are above that. We are here to help you if you need it. We may not always have the same answers but our goal is always to make your carb perform the best it can for your engine.

The List:

1 A carburetor can only perform as well as the engine it is bolted on. If your engine is junk, then all the carb work in the world won't fix that. We will need for you to do a compression check on your engine and post those numbers when/if you get to item #8 and also make sure that valve lash is set properly and that the spark plugs, wires etc. are in good condition. It is also highly recommended that you have a vacuum gauge installed as well!

2 Read the 2 circuit conversion thread through at least twice.

3 Read the Tuning A Dominator Transfer Slot thread through at least twice.

4 Purchase the necessary tools and parts to complete the conversion. If you need info on where and what to buy, there is a post below this one with pictures and links to vendors some here have used in the past. There is also some info on this in the 2 circuit conversion thread.

5 Do all the necessary drilling and tapping needed for the conversion.

6 Make sure your transfer slot exposure is correct if possible. Too much? Then ask for help after you complete the rest of the list. Please note that Dominator t-slots have varied a significant amount over the years and as a result, idle jet (IJ), idle air bleed (IAB) and t-slot jet (TSJ) tuneup may also vary significantly from the "base line tuneup" between different Dominator bodies even when run on the same engine.

7 BASE LINE TUNEUP! The following tuneup sould get your engine running. Please note that it is VERY IMPORTANT to get the idle and part throttle part right BEFORE you go chasing the main jet (MJ) and main air bleed (MAB) size. Note also that it's best to plug the power valve restrictor (PVCR) holes with a blank set screws and use the same size jet in all 4 locations. Once best power is made with the MJ square, then a power valve can be installed and you can work the MJ size back to the power level you had with NO PV.

Main Jet (MJ)=#96 Square
Idle Jet (IJ)=.039
T Slot Jet (TSJ)=.055
Acc Pump Shooters=.035
Power Valve Channel Restrictors (PVCR)=.053
Idle Air Bleed (IAB)=.065
Main Air Bleed (MAB)=.028
Emulsion Bleed (EB)=.028 in positions 1 & 3 counting from the top

8 Assemble the carb using the "base line tuneup", set the float levels and try to run the engine noting the results. Please understand that the "base line tuneup" is just that and every engine may want something a little different. The main thing is that you learn what stuff does and how to apply it to your engine combination.

9 With your initial post in the Fuel Systems section please include the engine combo on which this carb was run and the results of your compression check you did. In this post, please include AFR info also if it's available.

10 Use the forum "Search" function to try to answer questions you may have prior to asking in a post. We've found that many start posting and wind up asking the same questions that have been asked before.

Author:  nomad [ Thu Nov 08, 2012 8:57 pm ]
Post subject:  Re: Holley Dominator Two Circuit Conversion Help Procedure

Here are some examples of the tools needed and methods of drilling air correctors and emulsion jets.
Drills. These can be purchased on Ebay or other places online. My favorite place online to buy stuf is McMaster Carr. They have everything. But most importantly they will have the set screws needed for drilling.
The set screws to order are: Brass set screws with cup points. They need to be 3/16" long. Order them in 6-32 (emulsions and idle jets), 8- 32 (powervalve channel restrictions) , and 10-32 ( air correctors).


Pin gauges for sizing bleeds and jets being drilled or existing items. These items came from Ebay. These are minus sets and there are $60 invested in both. The small set is .013 - .060. The large set is .061 - .250.



Drilling bleeds. Chuck the blank bleed in the drill, the drill bit in the pin vise, and drill slowly. Use a lube such as WD-40 to keep bits sharp


A place to put finished bleeds and jets. I just use a small sticky label to write the size on and stick it to the lid. I got my boxes at CVS but, I've seen them at Walgreen's and K-Mart.


Taps. These are also found at McMaster Carr You'll need them in the same sizes as the set screws. Most taps generally available are tapered starter taps. You can do all your holes with these. My preference, however, is to start a couple of turns with a starter tap and then finish to the desired depth with a bottoming tap. And use WD-40 or 3 in 1 oil when tapping to avoid loading the tap with material.
Read the following threads again. ... f=6&t=3742 ... f=6&t=3811

Author:  nomad [ Sun Nov 18, 2012 9:31 pm ]
Post subject:  Re: Holley Dominator Two Circuit Conversion Help Procedure

When it comes to aluminum billet metering blocks most racers I know prefer the BLP, AED, Proform, or QFT brands. They seem to work the best for our needs. They all pretty much have the same mainwell dimensions. They'll also have some differences in emulsion placement and/or the types of emulsion jets required. Not a big deal. Avoid the offshore stuff.

Most of the work is done in the billet blocks. All you have to do with them, really, is open the mainwell exits, lower the idle restrictions, and plug in your calibration (tune up). Do the billet option if at all possible.

If money is a problem. And if you're a racer money always is. You can modify the 2 circuit OE stock castings from Holley. It's a lot of work and the zinc is a horrible sticky metal when it comes time to tap it. Use lots of lube. Do not buy NEW Holley cast blocks. The overall savings just isn't there.

This first picture is of an older stock Holley metering block. Notice the two center (mainwell) plugs are lower than the others (idle well). Not all stock metering blocks have the mainwell plugs so low in the well. Some are flush at the top like the idle well plugs and they are cupped plugs too, like a mineature freeze plug. For what we are doing here either style is just fine. This is an example of a GOOD stock Holley metering block.


NOTE: There are some metering blocks with flat plugs flush with the top of the casting. Sometimes, these contain emulsion tubes that are very hard to see looking down the crosswell or exit channel. They cannot be seen by looking in the jet hole either. If you have some of these metering blocks it's better just to move on to another stock Holley set or the billet blocks that were mentioned up the page.

Again, the block below is the WRONG type/style Holley block and should NOT be used!


This next photo shows where the idle feed restriction (or IJ) is in the older 2 circuit metering blocks. Just where it is supposed to be. The pencil is pointing to the brass restriction. If the restriction is smaller than the size you need, good. You can just drill to the larger size you do need. Just be very careful. It's easy to snag the little insert and pull it right out. Then you will have to drill and tap.


The pencil is now pointing to the location of the emulsion jets. There are two per side. Even though they appear to be wide open they are not. When they drilled, the factory stopped just short of breaking through to the main well. Then the appropriate size hole was drilled in the bottom, which served as the emulsion jet. Sometimes these were .026 or .028 in size. Check them with your plug gauges. You did buy a set of those didn't you? If yours are sized at .028, fine. If they are .026, that's fine too, go with that. They can be enlarged later if needed. As a note, these emulsion holes can be tapped for a 4-40 set screw. These will work just as well as the expected emulsion jet sizes will work in a 4-40 set screw.


The pencil is pointing to the kill bleed. In most cases it is located in the mainwell exit. Sometimes, it is located farther up in the emulsion air channel beyond the curve. If that's where yours are located don't sweat it. It's okay.


These are the power valve channel restrictions (PVCR). If these are larger than .070 or so drill and tap for an 8-32 set screw. When you begin to tune for a power valve it's likely you'll end up in the .060ish range.Then plug it with blank 8-32 set screws and install a power valve plug when assembling your carb. PV tuning will come later. If these holes are smaller than .070, leave them. Just install the power valve plug.


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