Power valve

When we got our power plant it came with a 750 Quik Fuel carb with 4.5 power valves in it . It met an unfortunate end in an event with the rear bumper of another car that was running second arguing over real estate for the lead that decided to climb the fence . So I Bought a Willy and it has 6.5s in it . I know, I know, I should just call Willy, but right now I am typing and he aint. So the Motor pulls 10 inch vacume (barely) and has a lil sputter just off the corner a few yards out and runs rich as heck idling in the shed with it turned to the lean side also . Need new PV i'm sure . Whats the best choice 4.5 or 6.5 ?

There is a lot of elements that go into the answer. But from my experience sounds like its dumping to much fuel then cleans out. PV should have no effect when carb is on idle circuits, as it only helps transition to jet. one may look at emulsion configuration and compare.

4.5's is what I run. Always have terrible luck with 6.5's.

On your rich idle- look at the top of the carb.There a 4 small jets very close to the accelerator pump squirters,these are the high speed bleeds.The 4 on the outside of these are the idle bleeds, going bigger will lean the idle.

Ok let me clarify a little to all , as my hunt and peck typing don't always clearly communicate what my brain is transmitting lol. The PV's that I have are old (both 4.5 and 6.5s 5 plus years old )and I can't suck them shut by mouth even after lube and working them . No rude comments please ! The Willy yes had a stumble at one point but we were adjusting it wrong ( I think ) stumble is gone now with new adjustments. Its running rich in the shed at idle because the PV's are stuck open ( I'm pretty sure )Yes or No ? Love my Willy carb to date tho so I'm not running it down by any means ! Its the best chit I have tried so far

if you are sure power valve is bad replace it. if it is large camed motor and dosent produce lots of vac go with a 4.5 . while u have it off, set the throttle plates on back to plates to wear they divide the small hole in the venture. I always do both as is good starting point. put carb back on. that's a four corner idle carb. books say turn all the way in on idle screws and back out two full turns, I always go 1 1\2. good starting point. Fire car up and bring up to temp. either use a vac gauge or tack to adjust idle fuel mixture. at this point look down in carb to see if fuel bleeding over. if so check float level. set idle as desired. I have seen people adj rear throttle plates and will move plates from desired location causing car to run rich and idle high making it blubber. then clean out at wot. also to the post above, as part of weekly routine always take carb cleaner and plastic tube and clean air bleeds out real good every week. Good luck hope this helps....

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Originally Posted by rgrmotorsports

if you are sure power valve is bad replace it. if it is large camed motor and dosent produce lots of vac go with a 4.5 . while u have it off, set the throttle plates on back to plates to wear they divide the small hole in the venture. I always do both as is good starting point. put carb back on. that's a four corner idle carb. books say turn all the way in on idle screws and back out two full turns, I always go 1 1\2. good starting point. Fire car up and bring up to temp. either use a vac gauge or tack to adjust idle fuel mixture. at this point look down in carb to see if fuel bleeding over. if so check float level. set idle as desired. I have seen people adj rear throttle plates and will move plates from desired location causing car to run rich and idle high making it blubber. then clean out at wot. also to the post above, as part of weekly routine always take carb cleaner and plastic tube and clean air bleeds out real good every week. Good luck hope this helps....

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Ok thanks . The rear plates were being used for Idle per original carb spec but have changed that to normal with the fronts . Ran fine during the test date .

Great hope I all works out for you. If you don't mind post after your race and give update if it was better. Have great week end of racing....

It will be a few weeks yet before we run . We got a lot going on right now .