ok i have an all original 84 with 305 Electronic Spark Control system

when its cold the idle is crappy, but right when the thermostat opens it will speed up and run great

also when its still cold it will run fine at part throttle and above, never bogs or anything else

any ideas ?

otherwise its a great running engine, just crappy at cold idle

it has NB1 closed loop, and federal emissions, thats 48 state

NB1 EMISSION SYSTEM, CLOSED LOOP
NA5 Federal Emission System

thanks for anything

 

What do you mean, when the thermostat opens it speeds up and runs great?
? When you first cold start it, tap the gas, and crank it over, it goes onto the fast idle cam right? Then the choke butterfly opens right away right?
How fast is your fast idle? 1500RPM cold? How far does the choke butterfly open when cold? Should be roughly 1/8".

ok, here's how your choke works, in case you didn't know:

1) The fast idle screw - sets cold start speed
2) choke pulloff screws - sets how rich it is at cold idle (by blocking off airflow)
3) The thermostat, how far it's turned clockwise or counter clockwise - sets
how LONG it stays on choke mode. Ie, how hot your motor has to be before it's off choke.