Two 750s and C12 Gas

[Ken0069]

OK so I got my engine running last weekend with two 4150HP Holleys that are "out of the box" carbs. I pulled some idle data and a couple of run ups part throttle on the Tbrake and it's sounding/showing it's rich at part throttle but there really wasn't enough time for the pump shot to clear out. It's got .075s in the IABs right now and I'm thinking of upping that about .010 or so should drive around data at the track show it's rich there.

Question is, how much IAB could one consider as "normal" for a dual 750 gas setup and or how much would be considered too much?

Next question is right now it's got .036s in the MABs and if changes are likely needed, which way would it likely go?

Reason I ask is because I'd like to pre drill some bleeds before I go to the track and I'd like to have some in the right direction.

We were planning to test this weekend but it looks like rain for sure tomorrow and possibly Sunday too. This coming Wednesday is looking good at Roxboro so we'll probably go there.

I've still got to do something to the hood as the front carbie doesn't have enough clearance. It's looking more like it will be some kind of carb mounted scoop sticking up thru the cowl hood much like what Jerdog has on his Camaro.

Dayum I hate working fiberglass!

[jmarkaudio]

Well, I have not run dual carbs, but from Tuners dual Dominator post the IAB and IJ will both be smaller than for a single carb. 8 idle circuits vs 4 means more fuel. Also keep the t-slots as tight as possible, around .005 showing probably for the same reason, with closed blades at a given idle speed you will have the same vacuum pulling from more sources. If I had to guess on the MAB's I'd drill .033 and .030 to take with you.

[Slowpoke]

I'd have some .022's to .026's on hand. If you go with .022's you can open them up at the track 1 step at a time, easy enough. Basically if you are too small it's just going to slowly go rich as you go down the track, which is a safer place to be tuning from.

[Scott Smith]

Your leaving the factory emulsion alone? That's why the MAB is so big to compensate for all the emulsion. I believe its .028 x 3.