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Old 03-01-2009, 01:48 PM   #1
Michael Mayben
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Default Holley Power Valve Thread

All Holley carbs used in ihc applications incorporate some form of enrichment system when the throttle plate angle is changed from a "cruise" position (high manifold vacuum), to a "more power" position (lower manifold vacuum). As the throttle plate angle is increased.

Early Holley designs have a circuit referred to as the "economizer" system. And we've jawwed about that stuff quite a bit in these threads:

http://www.forums.IHPartsAmerica.com...placement.html

And:

http://www.forums.IHPartsAmerica.com...ley-issue.html

The Holley 22xx series mixers have a very similar system, also called a power valve...but those items are actuated by a vacuum-sensitive "piston" that opens and closes the power valve in a "toggle switch" manner. The 22xx carbs have their own issues regarding that system, mainly in the area involving the actuation piston.

The Holley modular carbs all incorporate a replaceable power valve, components available in many different "values" and can be easily changed out for fine tuning any Holley modular mixer once the overall dial-in of the carb itself has been achieved during performance tuning. Likewise, fine tuning of the power valve actuation point May also affect both overall fuel mileage (especially in hd towing use) and "cruise" emissions levels.

Attached is a page from the current Holley catalog that explains in simple form how a power valve for a modular carb May be selected during the tuning phase. This catalog is available for download on the Holley website.
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Old 03-01-2009, 01:54 PM   #2
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Default Re: Holley Power Valve Thread

In this thread, I gave an example of how a mityvac hand vacuum pump with accessory kit May be used around the shop:

http://www.forums.IHPartsAmerica.com...ac-thread.html

Let's elaborate on the use of the mityvac in testing a modular power valve.

This shot shows the current mityvac design which incorporates a much nicer vacuum gauge (high resolution) when compared to the earlier models. The scale on this gauge reads easily in 1"hg increments and 1/2"hg values can be easily eyeballed.

Also I've mounted the "suction cup" adapter that comes with the kit called out in the mityvac thread...the perfect tool for testing a power valve!!!
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Old 03-01-2009, 02:09 PM   #3
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Default Re: Holley Power Valve Thread

Here is a new Holley "single stage" power valve, right out of the package...current high flow design referred to as a "picture window" style based upon the use of the large rectangular openings through which liquid fuel my flow unimpeded.

Notice that the valve is in it's "relaxed" state as no vacuum is applied to the diaphragm. The valve poppet is all the way to the right in the pic, held in that position by the calibrated spring. That is the position that the valve achieves when ever the throttle plate angled is increased resulting in a drop in manifold vacuum. Another term for that position would be "wide open throttle" (or wot).

When that valve is installed in the carb and the engine is started, manifold vacuum is highest. Manifold vacuum is supplied to the diaphragm on the manifold vacuum side and the valve poppet is pulled closed, and remains closed at all times until manifold vacuum drops to the setpoint for the power valve itself.

That means the carb is supplying an air/fuel ratio based upon all internal system/circuit calibrations designed into the carburetor with the engine at idle and up through tip-in and into cruise mode as long as the throttle plate angle is increased very slowly and manifold vacuum is not allowed to drop. The overall "mixture" ratio is being metered through the idle and tip-in circuits with calibrated fuel flow through both main jets, even at curb idle speed.

When accelerating away from a dead stop in a "normal" fashion such as a residential street system with a speed limit of 30mph, manifold vacuum would remain highest if being observed on a vacuum gauge visible to the driver.

If...a full throttle "launch" is affected (or similar when a slope angle increase is experienced in an off road situation), or in towing...a significant increase in load is experienced by the engine, then manifold vacuum drops, the power valve immediately reacts by opening, resulting in an equivalent "enrichment" of the air/fuel ratio equivalent to six>eight steps in main jet orifice diameter/flow rate. And this type power valve (single stage does react somewhat like a toggle switch, either "off or "on".
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Last edited by Michael Mayben; 03-01-2009 at 02:17 PM..
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Old 03-01-2009, 02:29 PM   #4
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Default Re: Holley Power Valve Thread

Here we see the #45 power valve has gradually had vacuum applied with small pulls on the mityvac until just the point of the poppet valve seating fully May be seen.

To test a valve of any unknown setpoint...simply repeat this test several times and observe carefully the action of the valve poppet. If the power valve is in serviceable condition, the reading you see will be very repeatable.

In this case, the vacuum gauge reads approximately 4.5"hg and will hold that reading for several minutes/hours!

If the power valve is "blown", then it will not actuate at all when the mityvac test is applied. Replace the power valve with a known good unit at that point.

If the power valve has been in service for some time, the e10 fuel May have affected it's impregnated diaphragm material causing it to become extremely stiff and non-responsive. Stale/deteriorated fuel residue that is present in carbs that are not operated onna regular basis will exhibit the same issue, and is worsened if any moisture has been present in the fuel delivery system which settles out in the power valve "wet" wide.

So...to test a power valve...there is no need for any type of specialty tester as marketed by a few of the performance carburetor vendors. A mityvac with an adapter set is all that's needed.

And...if the carb is on the bench for overhaul/service, ya can use the mityvac to apply vacuum to the actuator port on the throttle body to test the entire system if you tightly hold the metering body against the main body with a new gasket. To do that, ya simply remove the fuel bowl and watch the power valve poppet when applying vacuum.
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Old 03-03-2010, 11:06 PM   #5
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Default Re: Holley Power Valve Thread

The latest fwb klusterscru involves an original IH app model 2300 carb list #6391. Often when an original 2300 carb is discussed on this or similar forums the list #2977 is usually associated with it, sometimes incorrectly. What some folks forget, myself included is that there were a great many variations of the 2300 model carb found on IH light vehicles from 1965 up through 1974 on emissions-exempt rigs, the 2977 and 6391 being two common examples.

This particular mixer had been remanned multiple times as evidenced by round q/c stickers on the top surface of the airhorn and a square sticker covering the id numbers on the front of the horn. Johnboy acquired this'n from another local binder owner. It had been on this guy's 345 for awhile before he went TBI. Anyway, we stuck this on the 304 in john's '77 sii to replace the original 2210 which was in a sorry state. I adjusted the thing as per my training from binder u and the engine seemed to idle alright with verified accel pump shot. Drivability of this rig turned out to be rather sketchy in certain situations, primarily right at tip in. The thing would regularly burp, fart, sneeze and fall flat on it's face. Sometimes the engine would die. Kinda dangerous. At sustained cruise it was decent, with perhaps just a hint of lean surge.

This past weekend, I made it my goal to try and work out some bugs, either via adjustment or by swapping on a freshly rebuilt 2300 which I know was dun guuder under prof. Mayben's supervision. Upon paying closer attention to idle quality, I detected a mild miss at curb idle. Try as I might, nothing I did made this miss go away. So I swapped on the fresh 2300, dialed in the adjustments, and noticed an immediate improvement in idle quality. The miss was completely gone. We took it for a test stroll around the neighborhood and the dam thing didn't so much as sniffle it's nose! We dun a guud job on that'n, mayben! We didn't really git tuh open 'er up, on an extended stretch, but I was very pleased with the marked improvement.

Why am I posting this in a power valve thread? Patience...I'm getting there. So tonight I decided to bust the problem 2300 down at least far enough to see if anything unusual jumped out at me. Obviously the thing is scruud somehow and needs a complete inspection/overhaul before it can be put back in service. I thought perhaps the accel pump diaphragm might be the wrong size. Nope, it was correct. So then I removed the fuel bowl. #51 jets...nothing weird there. Then I pulled the metering block and noticed the power valve had the number 13 stamped on it. Now I'm still fairly new at this shizz, but that jes don't seem raht at all. I suspect this valve played a major role in the shoddy performance. Am I on to something? I gotta git this'n fixed up guuder. I let johnboy and jerry swindle me outta that flawless 2300 in trade fer this clunker. Yoozjoolee I lyk tuh git kissed afore I git scruud that hard!
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Coal Trickle - '99 Dodge Ram SLT 2500 Q-Cab SWB 4x4 - 5.9L 24V CTD/NV4500/8800# GVWR/12K# winch
Hooty - '74 SII 4x4 - 392/TF727/D20/3.73 D44's/Spartan FA/Krac-lok RA/RC 4" SUA/34x11.5 TSLs/33g Fuel/8K# winch
Lemuel - '72 1210 LWB 4x4 CS - 304/TF727/NP205/RA D60 4.10 - "Pull Lemuel, pull!"
Mongo - '71 1210 LWB 2WD - 345/TF727/RA17 D60 4.10 Krac-lok - "Mongo love candy! Duh, huh, huh!"
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Old 03-04-2010, 07:50 AM   #6
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Default Re: Holley Power Valve Thread

If the only stamping you can see on the diaphragm retainer is the digits "13", then that tells me it's an aftermarket clone power valve. And if it has just either two or four small hole around the perimeter, it must be gasketed with that fiber washer that has three internal "lobes". And it's entirely possible that the diaphragm has stiffened from age and exposure to fuel, that's why we replace 'em.

The "picture window" power valve has superseded all other designs in ginyoowine Holley parts, that one must use the round od/id fiber washer found in the carb kits. The picture window version has either two or four large rectangular openings instead of the small holes in the earlier parts.

However, I really think that the problem with that carb (other than being nasty and needing total luv, is that the metering block is gunked up internally.

This pic shows what I mean, though you can't see down inside the wells where the real problem lies! I've removed the plugs in the main wells here, you can see the "white rust" down in the holes. That is blocking all the internal circuits in that block and is exactly why the carb was sent to me after numerous attempts to make it operate correctly after rebuild by a pro! Two of the four plugs in this one are brass cup plugs, easily removed. The other two are lead plugs that have to be carefully drilled out. I have replacement plugs of several types/sizes for doing this kinda stuff, all the 1904 main wells that Robert reconstructs for ihon have been surgically cleaned internally also, if ya don't do that, the carb performance will be shit!

I have a two part methodology for dealing with that which is normally always successful, I'll train ya next time you are here if ya bring the carb with ya. And it involves some tooling which ya probably don't have but is easy to obtain and stuff you will use over and over, not too much dinero for a dude with a j.o.b.!

This same thing is why so many of the 22xx rebuild attempts that folks attempt are not successful, even though the main wells are integral with the carb main bodies, those can usually be salvaged also.

White rust is a reaction of the zinc and aluminum material when exposed to moisture over time. Such as when a carb is allowed to sit in the rain inna boneyard, or not treated kindly in the shop! And now...the condition is much worse when I see any carb for rebuild due to the debilitating effects of the alcohol solution that we are forced to burn now called e10. Not only does the alcohol attract a mega-dose of atmospheric moisture, it is corrosive to the metals used throughout the fuel system.
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Old 03-04-2010, 03:47 PM   #7
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Default Re: Holley Power Valve Thread

I didn't witness any white rust on the easily visible surfaces. In fact the inside of the bowl and the wet side of the metering block both look good enuff tuh eat off of. I know that don't mean it ain't hyd'n out in sum deep, dark krevass. If I give you all the numbers, would you be able to tell if the Holley kit that we use would have all the proper gaskets for this thing, or do you really need to see it in person? There ain't no hurry on the pyl. I can easily bring it next time I come up. Now this has totally turned into a 2300 tech post. I really thought I'd found some high performance, circle track power valve that was enrichening things at the wrong dam time fer a traktur motor.
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Favorite hobby...Driving Salma Hayek in my Scout

Coal Trickle - '99 Dodge Ram SLT 2500 Q-Cab SWB 4x4 - 5.9L 24V CTD/NV4500/8800# GVWR/12K# winch
Hooty - '74 SII 4x4 - 392/TF727/D20/3.73 D44's/Spartan FA/Krac-lok RA/RC 4" SUA/34x11.5 TSLs/33g Fuel/8K# winch
Lemuel - '72 1210 LWB 4x4 CS - 304/TF727/NP205/RA D60 4.10 - "Pull Lemuel, pull!"
Mongo - '71 1210 LWB 2WD - 345/TF727/RA17 D60 4.10 Krac-lok - "Mongo love candy! Duh, huh, huh!"
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Old 03-04-2010, 09:59 PM   #8
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Default Re: Holley Power Valve Thread

Okay, here's some pics to illeestrayt wut I got goin' on here. Sailor jerry sez this thang iz real purdee! He wants to jes scab 'er back tuhgether and call it gud enuff fer gummint werk. The black residue on 003 is just trace gasket material from the old skule organic gasket. Scrub hard and she comes easy! in addition to the #13 on the power valve, I see a marking that looks like p8. Thar ain't no winderz on this'n, jes pin holz. It did have the special gasket. In image 010, you'll notice a fracture in the skinny vein. Looks like sum ham-fisted lumm-ox dun smakt it with a bfh or gripped it with sum grippeez whilst tryin' tuh separate it from the manny. I don't think it's anything but cosmetic. Cud I putty it with jb weld jes tuh keep the loose piece intact? Last but not least, image 011 shows the choke butterfly has a nice wow in it. No doubt that wuz a rednek attempt at freein' a stuck choke. Yep, papa mayben, this'n needs sum luvin'. Sorry jerry. She's outta kumishun fer awhile.
Attached Images
File Type: jpg 6391 001.jpg (86.3 KB, 713 views)
File Type: jpg 6391 002.jpg (65.8 KB, 678 views)
File Type: jpg 6391 003.jpg (81.6 KB, 1357 views)
File Type: jpg 6391 004.jpg (41.1 KB, 631 views)
File Type: jpg 6391 005.jpg (46.7 KB, 3079 views)
File Type: jpg 6391 007.jpg (80.8 KB, 621 views)
File Type: jpg 6391 008.jpg (60.3 KB, 539 views)
File Type: jpg 6391 009.jpg (78.4 KB, 1014 views)
File Type: jpg 6391 010.jpg (61.1 KB, 609 views)
File Type: jpg 6391 011.jpg (58.0 KB, 681 views)
__________________
Favorite hobby...Driving Salma Hayek in my Scout

Coal Trickle - '99 Dodge Ram SLT 2500 Q-Cab SWB 4x4 - 5.9L 24V CTD/NV4500/8800# GVWR/12K# winch
Hooty - '74 SII 4x4 - 392/TF727/D20/3.73 D44's/Spartan FA/Krac-lok RA/RC 4" SUA/34x11.5 TSLs/33g Fuel/8K# winch
Lemuel - '72 1210 LWB 4x4 CS - 304/TF727/NP205/RA D60 4.10 - "Pull Lemuel, pull!"
Mongo - '71 1210 LWB 2WD - 345/TF727/RA17 D60 4.10 Krac-lok - "Mongo love candy! Duh, huh, huh!"

Last edited by Scoutboy74; 03-10-2010 at 11:14 PM..
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Old 03-05-2010, 08:10 AM   #9
Michael Mayben
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Default Re: Holley Power Valve Thread

That is a "two stage" power valve. Holley makes those but they can't be id'd from number stampings on 'em like the single stage units can. Those are sometimes found in certain aftermarket kits and are similar to the real Holley version but not the same. I don't have a methodology top test 'em that is accurate, so I toss 'em. A replacement two stage pv has become exorbitantly expensive in the Holley line.

I do run one of those in my carb after much experimentation, it gives no measurable improvement in fuel mileage though it does correct the issue (actually does not correct, but masks) created when disabling egr without recurving the distributor.

We did one in Matt g,'s fresh 2300 a year ago, he claims mileage improved maybe 0.5mpg and he drives in a very anal fashion!

Those retail for about $38 now, compared to an average street price of $14 for a normal picture window pv.

Don't be concerned with the crack you see in the carb, that started out most likely as a flaw in the die cast zinc. That is a strengthening "web" in the main body and unless it penetrates through to an internal passage, it's inconsequential.

You are right, that carb looks much nicer than what I normally see! But I always disassemble the metering blocks now for rebuild as varnish will hide deep inside and prevent correct operation. Sometimes the ones that look real nice on the outside, are totally plugged internally!

The hly-37-1543 kit will work just fine for that carb.
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