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Gone but never forgetten
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Ok, so I'm rebuilding the used Holley 750 DP that I got for my '69. It's a model 4150 (list no. 4779-2).

I cannot find where I put the instructions that came with the rebuilt kit, so I need help from you guys.

First, what height do I set the floats to? I know to adjust them once it's on the car, but I need to where to set them initially (I have the gauge that came with the rebuild kit).

Second, are the mixture screw seats replaceable? I don't see anything in the kit that looks small enough to be the seats, so I'm assuming you just leave them (there's about a gazillion other parts in the kit, though, for every model of Holley ever built *LOL*).

The biggest question, though, is about the power valve. This is what was in it (click on any pic for a larger version):
http://mach1.classic-mustang.net/misc/pwr_valve_plug1s.jpg http://mach1.classic-mustang.net/misc/pwr_valve_plug2s.jpg

Here's what's in the rebuild kit:
http://mach1.classic-mustang.net/misc/power_valve1s.jpghttp://mach1.classic-mustang.net/misc/power_valve2s.jpg

Is the one that was in there just a plug put in by the guy I bought it from? Should I put the one from the rebuild kit in instead? I've heard about people putting plugs in so as not to blow the power valves on backfire (and heard these plugs are not the way to go).

Or am I just thoroughly confused?

The last question, is what power valve do I have? The kit came with 2 identical ones (4160's use 2?). Stamped on the valve is a G, a 6, and 2 5's ... is it a 5, because there's more of that than the other 2 markings? *LOL*

TIA
 

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initial float setting, hold the float bowl upside down adjust the needle so that the top of the float is parallel with the bowl measurement is roughly a 1/4"
the stock power valve in the primary was a #65.
if he had a plug in the primary it probably ran like poop.
stock jetting 70 primary 80 secondary
 

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John there should be a little cork o-ring so to speak (for your mixture screw)that pushs into the metering block & your mixture screw pushs into that & screws into your metering block sealing it,i can,t understand why anyone would blank off the power valve on the primary side,the #,s stamped on the valve are a manufacturing code month "g"july,year"6" 06,size"25"2.5,the only one your concerned with is the size,they range from 2.5 to 12.5,a "65" stamped is 6.5,toss the blank one & intall the 6.5,the 6.5 means when your vacuum drops below 6.5 inchs the valve opens & lets additional fuel flow.
 

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John,

The plug goes into the secondary metering block for a double pumper and the actual powervalve goes into the primary metering block.

People only use a plug in the primary metering block for dragracing. The powervalve gives you your part throttle throttle response. It allows fuel to enter the engine right after the carb comes off the idle circuit and before the actual primary jets completely take over. It is a transitional circuit and you don't want do do away with it.

The real quick way to adjust the floats is to turn the bowl upside down and make the the float parallel with the top of the float bowl........

Gary
 

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I dont think that series of 750 had two power valves. Those kits are universal for the DP series and the 850 does use two so there's the extra valve for that. However they are not the same, the primary should be the 6.5, if you block the valve then the jet size on the primary will need to be increased, sometimes as much as 10 numbers so that you don't get a lean condition when you jump on the throttle as you will no longer have any enrichment from the power valve. I would definitely use it, and to be honest I have never had one blow out from a backfire, if you have enough backfires to do that then you have a problem elsewhere, obviously, usually I see them fail from sitting for extended periods and the gas in the carb gets stale and the power valves and accelerator pumps harden.
 
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