*Part 1* Converting a Holley Carburetor from a 2 circuit idle mixture to a 4 circuit

[@adamballinger1358]

Great video , I love how you explain the modifications , most videos on this tell you to buy a new throttle plate and new rear metering block . You show the way true hot rodders do it .

[@holleycarbshowtosadvice40y90]

Thanks

[@catpaw96]

Thanks for part 1 I have 2 4150S that I need to convert to 4 circuit idle for e85 can't wait for part 2

[@holleycarbshowtosadvice40y90]

Part 2 and 3 are on my youtube.

[@cavaleiro95]

Can you do a video on what’s the difference between a 2 and 3 circuit 1050 Holley carburetor? This would be strictly for a race engine

[@holleycarbshowtosadvice40y90]

Don't have a three circuit 1050 dominator right now, I'll try to dig one up.

[@SAM-eg7jg]

Had the base plate off of a 950 conversion double pumper/4 corner idle i had done years ago. 3310 780 main body to 850 base with the part number 12R-4507B and have also found it as Holley # 112-119. The idle passage has not been separated as shown in this video, does this need to be done..? I have also found some 850 aftermarket base plates with no passage at all, I am assuming these can also be used. Thanks so much for your videos i am eating this information with a large fork..!!

[@holleycarbshowtosadvice40y90]

Yes the plates came several ways some didn't have the idle track and some had a metal peg drilled and driven into the passage to separate them, but they need to be separated so that every idle mixture screw works independently of the other. The 12R-4507b, I believe is a engineering number. Keep thinking out of the box. Let me know if I can help you anytime with some information, I can tell you like to modify these holleys and I can tell you know what your doing, good luck!

[@NewEngland462]

I just converted a 4150 double pumper to a vac secondary 4 corner idle. Wasnt to bad

[@holleycarbshowtosadvice40y90]

What did you use off the double pumper?

[@fildela3651]

Hi and thank you ! Does this mean factory Holley carbs with 4 corner idle screws have separated idle channel cast in base plate, at the same place you put JB epoxy ?

[@holleycarbshowtosadvice40y90]

Most four corner holley carbs have a round pin drilled and driven into the same passage we epoxy., Which separates the idle passage.

[@clashofclams19]

What would happen if you put another primary metering block on the back?

[@holleycarbshowtosadvice40y90]

Thats part of converting from a 2 circuit to a 4 circuit idle system. I have a video that covers the complete modification.

[@trailerparkcryptoking5213]

👍

[@holleycarbshowtosadvice40y90]

Thanks

[@bobstephens8851]

Will a 4 corner idle base plate work with an older Holley with 2 idle circuit? I'm asking because I bought a 4777 650 Holley that has a broken base plate and I have a newer plate that's off of a 4 corner carb.

[@holleycarbshowtosadvice40y90]

Bob it should work if the plate is a stock holley 4 circuit plate ,some after market plates are different only difference in the 2 circuit and 4 circuit plates is the little bit of fuel it shares from the primaries to the secondaries , when you look at the 4 corner plate the machined idle track from the primary to the secondaries will have a pin driven into the idle track to block the fuel from the primaries to the secondaries, there are two pins , one on each side of the idle track, if you remove the pins it will be a stock 2 circuit idle system , hope this helps.

[@bobstephens8851]

@@holleycarbshowtosadvice40y90 Thanks for replying. The 4 idle plate is from a 750 Street HP and I might try removing the pins if they can be put back in. Don't want to make it a permanent 2 idle. Love your Vids by the way.

[@kurtellis435]

Hey Randy I really enjoy watching ur videos!! Can u do some video upgrades to a Holley 4412 please?

[@holleycarbshowtosadvice40y90]

I'll have to look through my carbs to see if I have one.

[@jeffpierpont4581]

Hello, On a 4150 750 HP carb four corner adjustment should the secondary plates be completely shut or have transfer slot be square. I have a problem trying to adjust the mixture screws and noticed twice that fuel is behind the secondary power valve plug. I'm not sure where this fuel is coming from. Any suggestions.

[@holleycarbshowtosadvice40y90]

Secondary transfer slot on a 4779 is not exposed at idle , primary side is square, secondaries close them then set them to 1/2 to 3/4 turn in , you have to balance the primary and secondary , you have the transfer slot exposed on the primary side and none on secondary side, which makes the primary side a little richer. Hope this helps. P/S with a four corner idle circuit never run secondaries closed.

[@sheaman220]

I stumbled on this video sifting through the comments of a facebook post. If you are able to get it to idle well with the standard set up why go through the effort?

[@holleycarbshowtosadvice40y90]

If your talking about converting to a 4 circuit this mod is more about racing, for all out drag racing, if your talking about something else explain.

[@MEC1955]

Will this work on the 4224 660 ct squirter carbs?

[@holleycarbshowtosadvice40y90]

I have never converted a 660 center squirter , but I believe that might be difficult , will probably have to epoxy secondary side of the body and idle holes may not be there , so its probably going to be tough , if you have a metering plate you will need a metering block and a longer set of bowl screws, and epoxy , I don't know if I would do it because 660s are hard to find,if you decide to do it be real careful. If you decide to convert it and run in to trouble let me know and we will talk.