I just installed a 650cfm DP Quick Fuel carb the other day. I've been having some tuning issues. Whenever I get into the throttle say 1/3-3/4 throttle it bogs/sputters and wants to shut off. If I cruise around lightly or nail the gas it runs good. My timing is set 20 initial, 36 total. Vac is 13-14 at idle and 8-9 in gear. My PV is a 4.5, squirters are 31's, blue pump cam on front, orange in the back. Jets are 72/80 and my floats are set right. I thought it might by my power valve at first, but in gear it has 8-9 so a 4.5 pv would be the right size. Where should I go from here?

 

It only sputters when you get into the gas like normal driving? Have you checked your plugs to determine whether its rich or lean? It sounds like part throttle mixture may be lean. That can be caused by a few things.

Main jets too lean.

Low float level causing the mains to come on too late.

Improper acc pump adjustment. Do your squirters work immediately when you just touch the throttle?

 

It definitly sounds lean. When you floor it your opening up the secondaries which are taking up some of the slack and trowing more fuel in there. I bet it's still lean at WOT. Was this a new or used carb? Has it been sitting around for a while by chance?

I would also think your car should pull more vacuum than it does,depending on the cam. Low vacuum makes it hard for the engine to respond well at low rpm's. Try adjusting the mixture screws on the carb. See where they are first by turning them in till they lightly seat,counting the turns. Open them back up and add one more turn and see if anything changes. Double check the initial timing to.
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I almost forgot....DUH! Make sure the accellerator pump actually sprays when the throttle is opened.

 

Have you access to a wide band O2 sensor? Best investment for my carbed 350 I've ever made. I've solved all my tuning issues. Drivability, 1/4 mile, mileage.

 

It's new used carb. If it sat around it wasn't long, it looks brand new. My is probably a mid-range cam (XE268). I've never had more vac than 13-14 at idle. I know for sure my floats are set right, I can look through the sight plugs and its about 1/4 -1/2 way up the glass while running. I'm going to try changing pump cams again when I get a chance. The squirters shoot as soon as the throttle moves so I know they are adjusted right. The carb is a four corner idle so it's a little pain to adjust but not too bad. It almost looked like I was running out of fuel on my front squirter but it could have been the pump cam profile. I'll relook at the chart Holley has and choose another one. I haven't checked my plugs since I bolted it on, I pull a couple whenever I get a chance to look at it.

I pulled a 700DP Holley off it before. It has 32 squirters, 6.5PV, 66/72 jets.

 

When choosing pump cams here is a good chart to go by

http://www.460ford.com/viewtopic.php?t=355