87Stallion

When Im driving in any gear and lightly mash the gas I get a slight stumble and then she goes. But If I floor it I dont notice it.

Im running a 650 DP. I thought I might need a bigger squirter on the primary so I went from a 28 to a 32 (all I had) and its still there. I dont have any squirters smaller than a 28. Could this be a rich stumble?

67mustang302

Which pump cams are you using? Did you try a pump cam in the front or on both ends that has a more aggressive profile? It might just need a bit more pump shot with less throttle, try to find a pump cam that delivers the same total volume, but gives more of it with initial tip in.

87Stallion

I am using the pink cams on the primary and secondary. I do have the cam kit. I just dont have the chart showing volume #'s for each cam.

67mustang302

The pink cam has the most total volume delivery, but the weakest profile. Buy the cam kit(well, 2 is better so you have 1 of each of the same cam for front and rear if you need it). Try going to orange front and pink rear...if the problem gets better then go to orange front and rear and see where it's at. Also, what holes are your current cams in?

87Stallion

I was going to try the brown in the front. I have them both in hole 1. I will try the orange one in the front and see what happens.

67mustang302

NOOOOOO!!!!!!!! Don't use the brown cam!!!!

That's the 50cc Dominator pump cam(and there's also a yellow 50cc cam). You most likely have the 30cc pumps....so if you use the brown cam it will probably tear the pump diaphragm.

If the pink cams are in hole 1 position 1 then they won't give any more at part throttle, so try just the orange cam in hole 2 position 2 up front and see if it helps.

Edit: Also, what is your linkage at? Progressive, super progressive or 1:1? If it's not at 1:1 get a link kit and change it to 1:1 and see how it drives.

87Stallion

Yeah I realized that when I got to looking at it closer. I did put the orange cam in but wasnt able to test drive it due to crappy weather. I just have whatever linkage came with the carb new. I looked up the 1:1 kit on Holley's site. I will order it. Does it make a big difference???

67mustang302

It can. Most guys that go to 1:1 end up with a better running car at part throttle. It lets you use both accelerator pumps at the same time on part throttle accel, which gives more tuning flexibility. It also has you running off all 4 barrels instead of the front 2, so you get better fuel distribution to each cylinder. It also makes the car more sensitive to throttle movement, since the same amount of throttle gives 2x as much airflow, so it gives you more kick for a given throttle motion(that's more of a perception issue though).

87Stallion

Ok I put the orange cam in hole 2 and took her for a drive. That made a hell of a difference. The bog is 99% gone. I am going to order the 1:1 kit. Thx for all your help 67.........

67mustang302

Is the WOT response still good? The pink cams in hole 1 deliver like 3.1cc per shot(hole 2 is 3.6cc I think) iirc, and the orange in position 2 is like 2.8cc.

This is some general info to keep in mind. Position 2 delivers more total fuel volume than position 1, but position 1 delivers more fuel on initial throttle tip in but less total volume. So hole 1 is typically favored for street cars that need good pump response at part throttle, whereas hole 2 is favored when you need a bit more total volume.

By going 1:1 on the linkage you can use BOTH pumps at part throttle accel instead of just the front pump. That way it's easier to get the part throttle pump shot you need and still get the right total volume.