i also posted this in the fuel system section. i know the cam is in time and the wires are on correctly. i have timing set at 10 btdc. i put some ported thumper e7 heads on a roller block with the f 303 cam. i have a 4 bbl intake with a 570 street avenger carb which was used and i never tried it until now. the motor only cranks up when i choke it and pump the gas 2 times. then i have to hold the choke almost closed and keep working the gas to keep it going and not really running very great still. it will rev fast and normal if i hold the choke almost closed and then hit it hard but if i try to rev it up without the choke i need to first pump the gas a couple times and then i can rev it fast. it won't idle unless i turn the idle screw realy high and still just idles for maybe 3 seconds. i know i have to get slightly shorter pushrods because i have to use shims and still am getting some sideloading of the valves but i wouldn't think that would cause my problem. does this sound like a bad carb. i do know that i couldn't get the fuel to come out of the front bowl at the site screw even when i turned the jet on top of the bowl. i am using a stock mechanical fuel pump which is new. the back bowl is getting plenty of fuel.

 

Sounds like you need to rebuild your carb to me.

 

yup, that carb might also be a tad small. look into an edelbrock 600cfm