Originally Posted by TJP
Originally Posted by Cab_Burge
I've seen many motors with Holley carbs that were idling on the transition circuit( the small rectangular slot that should be above primary throttle blades at idle RPM scope) which will open the power valves if the idle vacuum is below the power valve opening vacuum rating which makes the idle mixture very rich scope twocents


I believe the books I've read said the lower portion of the slot (.020 or so) can be exposed without ill effect ? confused

Me thinks the books you read are wrong, no slit visible works the best for me scope up
My old 517 C.I. pump gas stroker 400 motor with a low deck six pack on it would idle at 850 RPM in gear with 4.5 inches of vacuum with a 3.5 power valve up
thhat motor had 9.25 to 1 comp ratio with slightly ported 906 heads with bigger valves and custom grind Comp Cams solid roller that was 260 degrees @.050 on the intake with 1.6 rocker ratio with .700 net lift at the valves boogie
I learn many things with that car and motor, especially on the tuning of the carbs wrench up
Test, test and then test some more until you disappear in a blinding flash as exceed light speed grin whistling grin
Try it and see if that will work for you also wrench

Last edited by Cab_Burge; 11/03/21 03:27 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)