Pearl Z

I need a little help dialing this carb in or deciding if I have other issues going on with the motor. I currently need to tackle the idle before I can progress to any other tuning so here it is.


Car idles at 7" of vacuum and this fluctuates rapidly +/- about 1".
Idles extremely rich.
Cam is .540/.562 lift (plus 1.6 rr's)
242/248 duration @ .050 on a 110 LSA

Had a Speed Demon on it (that idled very rich as well) which is not recommended for such high duration. Took it off and have a Summit branded 750 DP.

Does anyone have experience with larger duration cams? Should I drill these butterflys to help clean up the idle? I can play with the air bleeds on this unit if need be.


Is this low vacuum and slight fluctuation inherent with a cam of this size or one one suspect something else might be going on?


Thanks in advance....I can almost taste driving this car on a regular basis.

Z28SORR

Whats your idle speed, RPM? How far open are the butterflies at idle?
The most common cure is to drill the butterflies.

Pearl Z

I can get it to idle at 1000 but the primary transfer slot is a little more than the .020 I'm looking for. The idle mixture screws are still functional but don't seem to do much to diminish the extremely rich idle.