Set & Tune Holley Carburetor Jets & Power Valves

How to select and install the right jets and power valves for your Holley carburetor. Includes information on jet extensions, when and where to to use power valve block offs, using vacuum readings to determine power valve opening point and more. An easy-to-understand video with steps you can do at home with hand tools.

[rodneyshute]

This video is killer helped me tune my swap
Meet double pumper to my 406sbc

[josephfriedrich]

Tearing down a hot rodded 600 that was mated to a bridge ported 12a. Trying to figure out why the po did what he did(jumped up a few jet sizes and installed a power valve plug) it runs right, so I didn't want to change anything, and after hearing your closing statement, it makes sense!

[wingchun]

Hello just found your channel love it love the lone wolf patch how to get one

[claytonstoolbox]

I hear you can put the 750dp main body on the 850dp base with a few modifications. Would you be familiar how to do that?

[huskynox]

It'd be nice to find one that explains the emulsion jet tuning in-depth, I can't find anything on the topic. It's be especially nice because a lot of the new Holley performance/race carbs are coming with the 5 hole blocks (Ultra XP, Track Warrior, etc.) but that amount of tuning isn't really necessary for a street car and just causes issues. It's difficult to find advise on what to do, or how to modify/jet those blocks for a street car. I've scoured the internet to find recommendations and have actually spoken to Holley tech's about it, no one seems to have much advise. I spoke to Holley just the other day about it, the tech didn't know much, but I did get some spec's for the different carbs (750/850 Ultra XP, Track Warrior) which seem to use the same 5 hole blocks, Holley was able to let me know that they install the same bleed jet stack in all of them, which didn't surprise me... The stack from bottom to top is .029, blank, .029, .029, .029. I was told by a guy that knows Holley's pretty well to go with this stack for the street - blank, .029, blank, .029, blank, so basically a 2 hole system. Going to say a 2-hole system, I would imagine will change the HSB's on the top also..? Thoughts? Recommendations..?

[JJ-jnue]

Wow, such great instruction and videos...thank you! Glad I found your channel Lone Wolf!! I am trying to figure out some tuning on a Holley 650 Double Pumper Ultra on a Ford roller 302 (actually 306). The motor has a Ford Motorsport E303 cam and is running about 10 to 11 Hg on vacuum...closer to 11 pretty consistently. I have a pretty good stumble (seems to be cutting out) as I accelerate, but when I punch it, the RPMs smooth it out. The carburetor has a 6.5 PV and I think 63 primary jets if the Holley site is correct. My idle mixture screws are maybe 1/2 from bottoming out to get the best vacuum, so I have to lean it out to get to the best vacuum. Anyway, I am guessing I need to drop my PV to 5.0ish...would I also need to adjust the jets down? I am near SLC, Utah, so 4200 above sea level. I am running an auto, 2500 stall TC and 3.55:1 gears.

[RockstarRanger]

With idle vacuum at 16in/hg I can't find a power valve rated at 13 or 14??? Do you mean divided by 1.5 or 2?

[stangbanger]

Anyone have an idea why my engine would stumble on after the ignition is cut off? Its a long rod 388 small block. .510 roller 210 lobe sep..base timing 14*.. it seems to get hot so quickly too.. Can't figure it out

[menoaz]

I have a supercharger question. My engine builder says I do not need to reference boost my carburetors and just put in 8.5 power valves and they will open down the track. This is for a race car application only have you seen this before? He says he has done it many times on the dyno with no issues.

[junkyardsearcher]

I am now more confused… I read somewhere that the power valve should be half of vacuum. So if vacuum is say 15-16 I believe that mine is 16-17 then you’re power valve should be half of vacuum… mine is currently 7.5
Am I wrong? Am I confusing the power valve with something else?

[junkyardsearcher]

I just noticed that you haven’t responded to anything in a year on this thread, I haven’t looked further, but I do hope that your health is okay.