This forum and Cliff's parts are great, I've been using the parts/info here for a while and finally have my first problem carb. I inherited this carb from another guy in the shop, it's never had identification #s stamped on the pad but it's a front inlet carb, non-electronic, with APT screw, originally had the idle mixture ports sealed off (and has flat idle mixture screws), is a big secondary unit and has electric choke. The carb was all the way apart (idle tubes out and all) when I inherited this deal and I reassembled it from there. The idle tubes are at .035, the upper idle air bleeds are at .065 and the idle mixture ports are at .085. The motor is a Pontiac 400 with a very mild cam and an ancient Torker single plane intake with a small fiber spacer under that like comes in cheap parts-store kits.
The car starts after two squirts on the accelerator pump, will run if you hold the primaries open any amount that drips fuel and revs ok but will not idle on the idle circuits. I've had the float up and down to no effect, nothing I've done to the carb has made the idle circuits have any effect. The idle tubes are clear, the idle down tubes are clear, the idle ports in the base plate are clear. The motor pulls 15 lbs of vacuum at idle with the primaries open slightly and is rough. Any ideas on what to check next? I have noticed that the power piston never pulls down against the APT screw (which is at 3 turns out) even when pulling 15 lbs of vacuum at what substitutes for idle right now, does this indicate anything? I have to have missed something, just don't know what? Oh, new throttle shafts all around and the needle/seat have been vacuum tested.
