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360 408 stroker carburetor problems

Lilred

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Joined
Dec 25, 2020
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Location
COLORADO SPRING
I recently built a 408/410 stroker for a 1979 Lil Red Express with bellow:

360 bored. 040
Kieth black pistons
Zero decked
.028 head gasket
65cc edlebrock heads
Harland sharp rockers
Rpm performer intake
650cfm edelbrock avs carb
7177 cam for now, but will eventually change
Duration at 050 inch Lift:234 int./244 exh. Advertised Duration:308 int./318 exh. Valve Lift with Factory Rocker Arm Ratio:0.488 int./0.510 exh.
2500 stall torque converter
3.73 gears posi

Currently i have low unstable vacuum at idle of around 5-8". The carb will not allow me to adjust idle screw low enough for the idle circuit. This is causing a very rich idle issue. If i hold the secondaries open a little rpms jump and vacuum goes to a solid 10"-12" depending on rpm . I have looked for vacuum leaks and evan pulled the intake to insure is was sealing. I have tried timing from 14-20 degrees with little affect. I have triple checked the lifter preload as well. I have replace all ignition components and verified that everything is working. Any suggestions on how to fix the idle circuit issue or what can be wrong? I am at high altitude and the cam is rated at 10" of vacuum at sea level. I was told i will probably need to drill the butterflies on the carb or go to a 750, but seems like it should work without.
 
Have you checked throttle blade to bore closure? Without closure the idle circuit will not work.
 
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