here's a bizarre one, my 85 camaro has a 305, 4BBL with ALL electronic components (sensors and all) removed. it has been modified back to basic old engine. when it gets warm out (roughly above 0 celsius and up) it idles like sh*t, backfiring and sputtering. when it gets below 0, it runs like a top. it has been below -40 lately and still fires every time and runs great. today hit +2 degrees, and it runs terribly again. have tried timing, carb adjusting, everything. has anyone else encountered this? i've had many shops look at it and nobody can figure it out. carb and intake are from a '78 firebird

choke is manually controlled as well btw

 

When it runs like crap have you tried playing with the choke i.e. adding some? It could also be an ignition problem and not carb related.

 

i have tried playing with the choke and it doesn't help the way its idling, just the idle speed. it does have complete new cap rotor wires plugs, but i guess i could check the pickup... never even thought of ignition acutally thanks

 

I was thinking along the lines of spark plugs but you changed those. How about the ignition module in the distributor?

 

ignition module is also fairly new. possibly coil issue? i kno i didnt replace the coil because at the time it tested out good

 

How does it act once the engine's warmed up?

 

even once it's warmed up, it still runs a whole lot rougher in warmer temperatures, but there is a very small difference when it warms up

 

So if you start it at -40, then when it gets up to operating temperature it'll run rough?

 

no, at -40 it'll run awesome once its warmed up, the problem seems proportional to ambient temp. i.e. the warmer it gets, the crappier it runs, regardless of engine temp.