High Flow Power Valve?

[Anonymous]

Anyone know the differences between a high flow Holley power valve and a standard?

 

[wsa111]

Holley's high flow power valves are used in the 2300 & other series, only on large engines which need a tremendious amount of fuel on the power circuit. The high flow power valve is not needed in a six cylinder application. Hope that explanation is satisfactory. william

 

[Anonymous]

Holley's high flow power valves are used in the 2300 & other series, only on large engines which need a tremendious amount of fuel on the power circuit. The high flow power valve is not needed in a six cylinder application. Hope that explanation is satisfactory. william

Thanks William,

I am tuning the carb with the aid of narrow band A/F and vacuum meters. At cruise the A/F is fluctuating between lean and stoic. When the power valve opens it does go rich, but only to the 2cd of the six rich led's.

To get more fuel at WOT I need to either increase the jet size or go to a high flow power valve. My understanding of the standard PV is that it begins to open at 1.5" before it's rating, and is fully open at that rating, the vacuum gauge confirms this. Wondering if the high flow has the same characteristic and how much more fuel it does flow.

Don

 

[CZLN6]

Howdy All:

Don, You may need to increase the size of the power valve channel restriction. The PV rating deteremines when the PV opens. The PV channel restrictions determine the amount of fuel passing.

The PV channel restrictions are the two small holes on the tapered shoulder of the PV opening. Assess what size you have by inserting the chuck end of small indexed drill bits into the hole. Increase the diameter in very small amounts. A .001" increase in diameter makes a bigger difference in areas, and that's what will increase flow.

I'd be curious what you end up with. I'm contemplating replacing my Autolite 1.08 with a #4412 Holley 2300. I'm running a modified 250, and live at 5,000ft elevations, so jetting, PV rating and PVCR are all critical to a clean running engine.

Adios, David

Adios, David

 

[Anonymous]

That is a good suggestion, I'll try the 62 jets first to see if it'll spend more time in stoic at cruise without going rich then tweak the PV as necessary.

Thanks
Don

 

[wsa111]

Don, The stock jet size on your carb is a 61, With a six cylinder you should be probably going leaner than richer?? Those holleys are jetted for 8 cylinder usage & normally require de-jetting. I would try a 59 jet & check for a air fuel ratio of 12.5 at full power, you rarly have to increase the size of the power valve channel restrictions. william

 

[godheadcustoms]

Don, what brand of A/F meter are you running? Some(most) of the narrow band meters are notoriously inaccurate. They will pretty much always cycle back and forth to some degree, the problem is they can't react fast enough to the changing enviroment of the engine. A wide band O2 sensor and meter will give much more precise results albeit at a much higher price. I used to be a tech at a fuel injection reman company and was always amazed at how far off some of the aftermarket meters were compared to our lab meters. Not trying to discourage you, just throwing out some info. Your carb may be more precise than your meter...
I would get it as close as possible, then have it dyno tuned with a wide band sensor for fine tuning. Just my 2 cents.

 

[Anonymous]

Gauge is by Autometer coupled with their O2 sensor.

 

[Anonymous]

Running rich at idle, no problem,that's about the 5th bar but only 2cd at WOT

 

[wsa111]

Don, just thinking out loud here. You said your idle mixture was rich. try this, set your idle speed to the desired setting but 25 rpm's above that setting, then turn the mixture setting clockwise to produce a 25 rpm drop in idle speed between the 2 idle mixture screws. This will help your fuel mileage & it will put your idle a/fuel ratio probable above 13 to 1 in air fuel mixture. this is a lean drop method of setting idle mixture.If you have a quality air fuel meter calibrated in say 13.50 to 12.00 air fuel ratio this is what you want. The guage maybe ok if you khow the air fuel reading i sugested. After using a professional air fuel meter for years you get a feel what is right & what is wrong. The only correct way is find a local chasiss dyno facility which has the proper equipment to give you a cruise a/f ratio reading as well as a power reading at full throttle. for god sake do not enlarge the power valve restrictions without getting a reliable full throttle reading from a professional guage reading.
With a holley if you can get a cruise ratio of 13.75 & a power reading of 12.50 to 12.00 be satisified. You can try the trial & error deal by leaning the main jets till you get a surge when cruising, then go 1 jet size richer. From past experience unless you run a big block ford or chevy, you will be leaning out the main jet size. Good luck william

 

[godheadcustoms]

Well...the autometer gauge is the one that most people are running and also one of the least accurate for tuning purposes. I really like autometer for most everything, but their A/F meter just isn't up to their standards IMO. Do you have any good tuner shops with a chassis dyno somewhat close?