Ok I have a Blower on my 86 camao running a 355. I've upgraded to the ZZ4 computer. Now my question is about the Pressure differential sensor (AKA MAP). ahould it be referencing the carberator or manifold pressure.

I know there is a flaw in the theory of either. The Carb will never really see 0 vacumm so the computer will never really see the motor under full load and there for will never properly adjust the spark and the fuel curve accordingly (this is mostly a drivability issue under part throttle not WOT). On the other hand referencing the manifold means it will see boost, which will mostlikely be seen as ) manifold pressure and could possibly trip the SES light if it occurs at part throttle. So I'm not sure which would be a better choice.

Now If you are going to tell me ditch the CC card and go Holley/Oldskool Qjet then please don't reply. the mission of this project is to make a CCC Q-jet run correctly with a Roots Blower AND Computer Controls. I am close to that goal, and I WILL not deter from it.

SPECS:
CCC Q-JET 780-800 cfm Bench flow.
ZZ4 Computer and chip
Ported, pocketed and flowed Cylinder heads 72 cc
-12 cc pistons,
276 int 268 exh 114 lobe center flat tappet blower cam
1.6 full roller rockers,
1 5/8" shortie headers w/ 3" hooker exhaust,
Camden Roots blower Approx. 168 C.I.
MSD 6A
Meanest 10 bolt you can build w/3.73's and a Eaton Posi
G-Force T5 w/ Zoom kevlar clutch


If you need to know anyuthing else please feel free to ask.
Thanks now for all the help

 

The pressure differential sensor (or VAC sensor- it's different than a MAP sensor) should be hooked to a vacuum fitting ABOVE the blower. No, it'll never be perfect but the stock chip programming won't supply any spark advance until about 3-4" of vacuum is seen at the VAC sensor. You'll never actually see that much vacuum under the carb at WOT even with the blower sucking it's brains out. Maybe an inch or two at most with a good flowing QJet. I have a QJet on top of my 383 with a 142 blower and I've never seen more than 1.5" of vacuum at the carb when wide open.

 

You Know, everytime I have a Q you have the answer. I owe you. Thanks Dude.