Posted By: 440 trucknduster
4150 750 double pumper ,no adjustments? - 09/16/08 11:34 PM
hi all, got a 60 over 440 with a holley double pumper with four corner idle.
i have no adjustment on the idle screws? can screw them all the way in and nothing happins? jets are 84 up front, 73 in the rear,the car is running rich,real rich?
any ideas on what is wrong? please help
Posted By: NITROUSN
Re: 4150 750 double pumper ,no adjustments? - 09/16/08 11:36 PM
Power valves bad, vacuum leak, plugged air bleeds, plugged passages.
Posted By: 440 trucknduster
Re: 4150 750 double pumper ,no adjustments? - 09/16/08 11:41 PM
thnaks, i have put a 2 and half power valve in it and new base plate gaskets ,havent opened the carb its self,
is there a way to clear out the cloged air bleeds?or cloged passages? with out taking it aparts? its practically brand new??
Posted By: Pacnorthcuda
Re: 4150 750 double pumper ,no adjustments? - 09/16/08 11:44 PM
Are you able to back off the idle set screw until motor dies? If not, and if the butterflys stop closing at some point when the screw is backed off then the idle-stop set screw (real small in the throttle body) may be adjusted to far open keeping the butterflys in the main fuel feed circuit. ????
Posted By: AndyF
Re: 4150 750 double pumper ,no adjustments? - 09/16/08 11:56 PM
If the idle mixture screws don't do anything then you aren't running on the idle circuit. Get it back on the idle circuit and your mixture screws will start working again.
Posted By: 440 trucknduster
Re: 4150 750 double pumper ,no adjustments? - 09/17/08 12:01 AM
ok,how would i get it back on to it
Posted By: Cudajon
Re: 4150 750 double pumper ,no adjustments? - 09/17/08 12:02 AM
Happens a lot on Holleys. Close down the throttle plate, If it becomes hard to start then play with the idle screws...Also what NITROUSN said (check those first).
Posted By: JimG
Re: 4150 750 double pumper ,no adjustments? - 09/17/08 01:19 AM
AndyF and CudaJohn are correct.
If you don't have a vacuum leak or or a problem with the carb, I'm guessing you've cranked open the curb idle screw to get the idle RPM you want.
Take tha carb off and flip it over. Look at the primary throttle plates. The 2 transition slots are, well, they're slots that are ~ .200 - .250 long. As each throttle plate opens, it uncovers more of the slot, as they close, they cover more of the slot.
I'm guessing that to get the idle RPM you want, you've got too much of the slot uncovered. When the throttle plates are closed to curb idle, you should only see enough of the transition slot that it looks like a square. If you're seeing a rectangle, that's too much.
The cure is to drill small holes in the throttle plates so you can close the curb idle to get the proper plate/slot relationship.
Jim
Posted By: doctor_mopar
Re: 4150 750 double pumper ,no adjustments? - 09/17/08 11:28 AM
It is also possible that if your ignition timing is not advanced far enough , you may be having to open the throttle too much with your trying to get a high enough idle speed, and thus the carb is not in the position for the idle circuit to work. Check your timing ! You may need 10 to 15 degrees advance at idle speed. I doubt that you need to drill the throttle blades ! First, If it is real rich, you may have a needle and seat with debris holding it open or too high fuel pressure. You need to set float levels with it running see if fuel is at bottom of sight holes !
Posted By: CJK440
Re: 4150 750 double pumper ,no adjustments? - 09/17/08 12:02 PM
You can give the secondary throtte stop screw a crank in leiu of drilling holes.
I'd start by backing out the idle mixture screws 3 turns each. Fire up the car and back out the idle stop screw to try to get the car to the idle RPM you want then get back to us.
Check base timing while you are at it. Make sure the vacuum advance is disconnected and plugged.
