emulsion tuning for dual quads? experts needed

[TheGreatPumpkin]

Part of that problem is that Voodoo hyd cam is a Baby cam for the dual quad engines.
The cam for the old Shelby dual quad engines was quite a bit bigger duration@.050". Solid lifter. about 244° @.050"
These deep breathin dual quad engines make more power but only if you let it eat... Cam choice and carb cfm choice. A 244° cam in these is just getting warmed up. The big cam likes the ton of idle timing and matches the idle air flow of 8 throttle plates at idle.

Do not be afraid to bias the throttle settings on the front/ back (pri) carbs. for effect.

The throttles definatily must be in its sweet spot at idle..
Too far closed is just as bad as too far open at idle.

try 900 rpm. VS 800 rpm idle speed too.

The diz (with a 10 deg adv curve should stay on the base initial (26 deg at idle) to about 1800 rpm off idle. Then start progressing the mech advance up as rpm rises.

Also remember with ported advance only the base idle throttle position is "ported" controlled. As soon as you step on yhe gas to drive it even a little bit. the vac advance becomes active. just like full manifold vac does.
From that point its the same same.
Most cammed cars work best on ported vac advance and the 10 degree mech advance curve that is more dynamicly stable and smooth.

ok got it. I'll get those dist bushings ordered tomorrow and try the ported deal. I've been told by so many people not to use ported, but this is not a stock setup so i'm pretty sure you're right, given your knowledge

[TheGreatPumpkin]

Also, Fbird, i know we talked about this before but i want some clarity, should I drill like a single 1/8" hole in the gasket for manifold heat crossover? Or one on each side?

Not today, but whenever the tune is all done

[HQM383]

Did you say you have increased iab to little effect?

I’d do the ignition timing Fbird is suggesting, trial ported vac adv and if still not where you want it drill and tap for transfer slot restrictions.

[TheGreatPumpkin]

So, here's the tune and the update. Went back to the stock 1850 metering blocks, with the only change being that I drilled and tapped for the IFRs

TB P: ~0.020 slot
TB S: ~0.380 depth
IFR P: 0.020
IFR S: 0.025
IAB P: 0.062
IAB S: 0.018
Jet P: #64
Jet S: #70
PVCR: 0.035
MAB P: 0.025
MAB S: 0.023
EB: 28/xx/28/xx
PV: 10.5
Nozzle: 0.025
Cam: Orange #1
Spring: Purple
Total Timing: 36
Bushing: Black
Springs: Blue/Blue
Vac Timing: 15 @ 15 Manifold

Idles, but can't sustain over 2000rpm just sitting there in the driveway revving it, it goes dead lean after a second and immediately if you try to give it gas - I'm guessing that's a clear indication that the IFRs are too small But maybe not, I might have made some mistake in carb assembly. I went back to the black fiber Holley metering block gaskets and maybe there's fuel and air leaking into the idle system? IMS 1/2 out would not get it even to .80 lambda. I messed something up I think

EDIT: I realized that I reused the QF transfer tubes, which are 1/4 inch longer than the Holley ones. I'm guessing that's preventing the blocks from sealing. Will report back tomorrow.

[F-BIRD'88]

Also, Fbird, i know we talked about this before but i want some clarity, should I drill like a single 1/8" hole in the gasket for manifold heat crossover? Or one on each side?

Not today, but whenever the tune is all done

That you have to experiment with..
I'd start with one side open and other side say a 3/8" hole.
If it get too hot then reduce.
This is going to effect the idle circuit set up.
The plenum heat makes it want to be different.