HOLLEY POWER VALVE TUNING- Everything You Need To Tune Your Power Valve | Holley Carb Secrets |

Holley Power Valve and How to tune power valve along with so much more info. I've got my carb ls dialed in and I thought I'd show you how to set up one of the most viable items on your carb. On my carbureted ls I installed a vacuum gauge and an AFR gauge and went to town. Theres very little info when it comes to a holley carb and much less when you get into the PVCR, IAB, IFR etc. Tuning a holley carb is easy, once you know how all the systems operate. Hopefully this helps someone in the future looking to modify their holley 600 650 750 vacuum secondary or double pumper. Trying to catch up to the driveway engineer so lend me your power!

[mikecondoluci]

IVE BEEN TURNING WRENCHES FOR 50YRS, I GOTTA GIVE YA 2 THUMBS UP CAUSE THATS ALL I GOT, GREAT VIDEO

[markcarter]

Great video. Yes once the power valve is tuned your engine will be a ton more driver friendly

[novakenss]

Nice explanation of power valve function. I never use the rebuild kit 6.5 valve. I have 7.5, 8.5's for my SBC since my normal idle vacuum is at least 18 in hg. Right now I'm using the 7.5 and there's no bog on the way into the primary main jets. In winter I may use the 8.5. My 650 Holley is an old model from the 90's but it's never blown a power valve. thanks for the video info.

[whiskeylima]

You could possibly be right, 570-600 cfm maybe be better for your application. Dual planes usually allow you to go down on jet sizing, not sure which intake you are using but they provide a stronger signal. Holley has a carb sizing chart based on displacement and volumetric efficiency of the heads. Cylinders 7&8 tend to run leaner on LS engines so you maybe able to dial some timing out depending on your ignition controller. Your headed in the right direction with your videos. I run a primary metering block with adjustable PVRC jets on my turbo application, will work on NA motors too. Keep at the informative videos.

[sheepdog.]

You're the man, appreciate your videos...

[whiskeylima]

Great video. Single AFR reading are an average. Total fueling or total fuel area should be balanced. Primary jet + power valve = secondary jet. Hence the common jet spread. If not fueling distribution will be off but the AFR gauge will have you thinking everything is OK. Jet area charts will help to know total fueling.

[monicacorrea]

For me, it was imposible to ignore that happy face on your hand!! 🤣

[toddresmen]

Great info. I bought a Quick Fuel SS 750 AN and didn't pay too much attention to the power valve. I think i compensated for the valve opening too soon and dialed back my main jets to compensate. now the quality carb is acting wonky and just don't know where to go with adjusting. I have a 6.5 PV and about 11 inches of vacum at idle. Im going to set the jets back to factory and use the vacuum gauge like you said otherwise i feel i'm just guessing. I have an airfuel gauge already so this should get me there! Thanks for the info and keep up the good instruction!

[stevecooper]

This really makes sense to me now.Thanks nightwrencher.

[randyjohnson]

I like your vidioes they are very imformative! I drag race and for the guys that are running a tall camshaft with lots of lift and duration you will have very little manifold vaccum at idle so low that you can not keep the engine running even by turning out the idle screws to richen the mixture, the fix is to use a 4.5 or less power valve to let more fuel into the idle circute so the engine will run! than adjust the idle jets and the curb idle. pull a few spark plugs and look at the color they tell the story of what is going on in the combustion chamber if they are black and wet you are running pig rich jet down 4 sizes and go from there untill you get a nice tan color. If you think your carborator is to big you can drop down six to seven sizes on the main jets to make the engine run good and lean, keep checking the spark plugsthis will save you from buying a new carburetor. there are a few good sparkplug reading vids out on utube check them out! hope this helps.

[theelcamino]

Thank you for these videos. my mighty demon 850 comes with a 4.5 PV. At lite cruise, it’s grumpy. It seems it needs one closer to manifold vacuum. I wish you had a driving video to show how you figure it out with a afr gauge and vacuum gauge. I bought drill able fuel bleeds and Air bleeds and a dual wide band gauge. You are right it’s hard to find info. It’s miserable and I want to make it correct.

[frankdatank]

Wow, excellent explanation of the power valve I have two carb tune books and it could not tell me the powe valve was the circuit after the primary jets!!! Good work!!! How about vacuum secondaries would these take the place of the primary pv since they also work under load through vacuum decrease, I had to delete my primary pv on my quick fuel 580HR, has exact metering plates as holley?

[jakedunne]

Great video. Questions though lol! I have a 454 chevy motor . Was built for a blower setup . Motor has a huge cam has 8.1 compression and runs 8 inches of vacuum at idle . I just had some work done on the car becaise of tuning issues at a local shop and the shop put a 2.5 powervalve in. Now the car stalls under load if im not constantly giving it gas . Do you know what it could be, or possibly a fix?

[tjbeck]

Where did you get that set of drill bits? I'm having trouble finding a good set like that for jets. Thanks

[baims]

What’s a good size to run on a Holley 500 ran on a 602 GM crate engine used for circle track racing ? 6.5? What’s a good accelerator pump size to use thanks ? I feel it’s a bit lean haven’t looked to see what a in it

Crate engine is turned at 6100 rpm. 460/490 lift cam.

[menoaz]

Looking at the vacuum gauge, when do I know when the power valve is opening up?.

[Dazza.]

I run a 570 street avenger and I’m going lean (up to 18 AFR)as the vacuum secondaries are opening with a 6.5 power valve and a black spring. I will try an 8.5 power valve and see if that helps.

[MattsRageFitGarage]

Good information. I've got several 600 cfm Holley carbs and they all seem to have wildly different PVCR sizes. I sold one of them so I can't measure but it ran really rich when the power valve opened under light to mid acceleration (10.5-11 AFR) so it's safe to assume that one was large. I have an 1850-5 Holley that has .042" PVCR and just acquired an 80145 Holley which is just a deluxe 1850 in center hung 4150 2 corner idle configuration, basically and it has .052" pvcr. I really want know what engine Holley thought a 600 cfm vac secondary electric choke was gonna run well with using 68/70 jets and a .052" PVCR because I have a pretty healthy running Ford 390 that sucks gas like it's already long gone out of style running 67/69 jets at 14.1 average cruise afr with the .042" PVCR that gets drowned down to 10.5-11 when the pvcr opens up LOL time to drill and tap that metering block tomorrow and reduce the size a little.

[arcorob]

I think you solved my problem. Trying to figure if my power valve or my accelerator pump needs to go UP> I have a 347, mild cam, pull 12-12.5 vacuum in gear idle. AFR reads about 12-5 to 13.5 idling. Cruise ( 14-14.5 at steady cruise) and if I hit the gas 1 inch I get a momentary lean stumble (AFR reads in the 16-17 range momentary before drops down and she goes like hell. I am afraid that persistent lean is going to damage my engine. My stock Holley power valve is a 6.5. The pump nozzle is a 31. Would you recommend I UP both or one at a time? should I go 7.5 or 8 on the power valve ? What about the nozzle? Thanks in advance...this is driving me nuts because the engine idle and runs AWESOME except for that split second stumble

[Granite]

Definitely going to ditch the rebuild kit power valve now 😅