Pro Systems Dominator woes

[michaelbarry]

Long time reader, first time poster here. I have a Pro Systems Dominator that has got me at my wits end and i'm hoping someone can be of assistance. This will be long, just hang with me. A few details... 532 BBF, C4 trans, 2700 lbs on the starting line, footbrake bracket racer. The carb has had an issue since new (almost 3 years ago now) with launching it anywhere below 2400-2500 rpm but I finagled with it a bit, got frustrated and gave up on it and would just be sure to not launch below 2500 rpm and all was well. Fast forward to this spring, I freshened the engine, changed the intake and added a vacuum pump over the winter. The thing absolutely will not launch without falling on its face and if I don't lift the throttle, it will completely die. I can launch as you normally would, it will fall on its face, lift my foot quickly then roll back into the throttle and all is well on down the track. I swapped my old Holley 1150 back on and it's right as rain. That being said, I've ran the Holley most of this year but I'd like to get the Pro Systems working as it was considerably faster than the Holley when it was somewhat working before. I've thoroughly inspected the metering blocks and main body, ensured all passages are clear, tried everything from 32-50 on squirter size, stock main air bleeds were at .032, I went down to .027 thinking it should increase signal to the boosters and bring them in sooner but no dice. I even swapped the metering blocks over to the old Holley main body that I have and that setup runs great so I feel that it has to be an issue relating to the main body. I've also sent the carb back to Pro Systems, got it back, bolted it on and same deal. Not sure what happened with the color but here's a video of it..watch the throttle linkage as you listen and you can get an idea of what's going on..any help is MUCH appreciated.

https://youtu.be/7ZTLDX32m5Y

[banjo]

Where are the float levels set? Try raising them up and see if it changes.

[michaelbarry]

I've had them everywhere. They're currently right about 5/8 of the glass on the side of the bowls so they're already pretty high.

[banjo]

How much tslot do you have exposed?

[michaelbarry]

How much tslot do you have exposed?

To get it to idle where I'd like for it to, 1200 rpm in neutral, 1000-1050 in gear, the blades are just covering the end of the transition slot. I've tried it with the blades opened a bit, roughly .020 open on the transition slots..no difference.

[banjo]

Does the main body have tslot restrictions?

What idle jets and bleeds does it have?

[michaelbarry]

Does the main body have tslot restrictions?

What idle jets and bleeds does it have?

The t-slot orifice in the main body is roughly .092, I cannot remember the idle feed restrictor size but the idle air bleeds are .048

[Tom68]

Looks like it needs more accel pump volume.

[michaelbarry]

Looks like it needs more accel pump volume.

That's the first impression for sure..has 50cc pumps on both ends, have tried different cam shapes, pump bolt adjusted from barely touching to pre-loading the pump (.030 or so from bottoming the pump out at full throttle).

[banjo]

Is it a cast holley body? To me it seems like it's the tslot is too short. How do the tslots on this carb, compare with your old carb.

[1972ho]

Have you tried more ignition timing are less to see if that helps.But that big block ford idle sound crisp and healthy ?

[michaelbarry]

Is it a cast holley body? To me it seems like it's the tslot is too short. How do the tslots on this carb, compare with your old carb.

It is a cast Holley body. I haven't actually measured the difference in length of t-slots between the old main body and new main body. But they appear to be close to the same in length without measuring.

[banjo]

I say length, but it's more location, and if they are too high, you have to lengthen it.

[abc]

It's still too lean. Do what you have to, add more accel. pump volume.

[michaelbarry]

Have you tried more ignition timing are less to see if that helps.But that big block ford idle sound crisp and healthy ?

I have not. Distributor is locked out at 32*..that's where MPH peaks at on the track. It doesn't makes much sense that it'd be an ignition problem being that the old main body acts right, however the thought has crossed my mind that it could be ignition related because the old main body is "tighter" and requires more effort on the pedal thus taking slightly more time to go WOT when slamming the pedal down. I don't buy that idea though, as this issue existed at the start of the year with this carb and I've ran all year with my old carb and no ignition issues whatsoever have showed up so I can't believe if there was an issue that it wouldn't have gotten worse in that time.