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Discussion Starter · #1 ·
Hey guys. I have a mild 350 sbc in my street rod. Really do not know the specs on the motor. But it is no street demon for sure, just a simple cruiser. I installed a 750 double pumper on it, basically because it looks really cool. It came with #74 jets. Had a hesitation when feathering the pedal. so I dropped it down to a 66. Way better but still not enough. dropped it down again to a 64. Even better but again not enough. decided to use a 60 but the store was out of them and only had #56. Does anyone think that that would be too small? Not a big deal to change them out but I really do not have much time these days. Would like to be done with this issue.
 

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You need to be careful. Those are big steps and if it gets to lean you will burn the tops off the pistons
 

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replace the power valve if its a used carb,use 69s in the front as a starter.
Is the carb new or off something else?
 

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Discussion Starter · #5 ·
The carb is actually brand new. I have no idea about the power valve but the float site window looks to be about 2/3 or so.
 

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lower the float so that it just barely trickles out the hole when you shake the car.Make sure fuel pressure is 5# or less.dont change Pv. your float level is way too high
 

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Thats not a try it thing,,,its how you set up the carb. It should have come with basic directions and tune up specs? post a video when shes runnin good
 

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More for Less Racer
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Hesitation when moving the throttle open is a accelerator pump adjustment change, pump cam change, or pump nozzle change, not a jet change.....you are already in dangerously lean jetting territory with the 10 sizes smaller #64 jet.

750 Holley should never need more than 4 steps leaner or 6 steps richer jetting, unless it is a blow-through turbo or supercharged application.

Make sure float level is correct first.
 

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For starters that 750 is really too big for a mild street motor. A 600 is a much better way to go.
Anyway...............check the accelerator pump adjustment. It should anywhere between .015-.020...............it has to be set a WOT(wide open throttle) Get a Holley book or just look it up online on the how to.
 
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