the one bbl carb presents some questions....BUT you say runs good EX with A/C on ... before we waste any $$$$ ...

spend 5 min get some A/C gauges post low AND HIGH readinga..
spend 5 sec open hood answer the questions about Idle speed kicker (solenoid)...

 

the mechanic had no right to switch the carb without permition just because he could not set the choke. if my mechanic did that he would not be getting paid.

 

pay or not pay-was that the question?

my missunderstanding....
I was replying to request fot TECHNICAL assistance ...ie ideas suggestions....

 

the truck is not getting enough gas and air when the a/c is turned on.

 

what diagnostic test is that based on?
what am I missing .... 70mph- no drivabilty issue - problem only with A/c selected....check NOTHING replace carb..?

 

the mechanic changed the carb to a 1 barrel. you loose horse power and torque. you are getting only half the gas and air. you need the horse power and torque or else you run into problem when you start using a/c or if he does anything else that would put more stress on the engine. there is a reason they came with 2 barrel carb and not 1.

 

assuming alot- based on an admitted laymans description.

there is much info missing- working with what we know - runs well?
turn on ac runs poor... I would 2 quick things AC pressure...ck idle "kicker"- time @5minutes

my swag ac compressor bad retro

 

the mechanic changed the carb because he didn't know how to set the choke.

 

There is 1 problem here for sure and there may be 2 problems. A one barrel carb simply can not deliver enough fuel for a 318 to take on any extra loads. It is enough to run the engine but not to allow the engine to develop full power. If you use a large enough 1 barrel to deliver any real power from the 318 under load you will not be able to set the idle because you will drown the engine in fuel at idle. There may be a problem with the AC and a check of that system would not hurt. My recommendation would be to first replace your mechanic. Then replace the carb. There is a fallacy that a four barrel will reduce gas mileage. This may be true if you are a lead foot but is not actually the case in regular driving. The primaries on a four barrel are actually smaller on a properly sized four barrel than they are on a properly sized 2 barrel on a 318 and therefore should result in a fuel savings if you don't lead foot it. If this does not completely cure the problem then check your AC system.

 

thanks to everyone. I'm no pro, but I knew the 318 had more power than this carb was giving. How much should it cost to convert to a 4 barrel (after I switch mechanics)?