Classic/Antique Car Repair: hard starting an amc, electric pumps, summit racing

Question
Hi Dick,

I have a '68 AMX with an original Carter AFB, correct to the engine. The carb was rebuilt a year ago or so, by a "reliable" rebuilder. Since then, I've checked the operation of the choke and it appears to work correctly. The problem is starting the engine from cold. I typically pump the accelerator five times or so, let off, and then crank the starter. It takes about ten to fifteen seconds of cranking to get the engine to fire. Otherwise, the carb. performs fine. How can I cut down on the starting time?

Thanks!

Answer
The problem of gas draining down into the intake manifold, or evaporating out the top of a carburetor when it is parked for a while is probably the most common complaint about old cars.  These days, when all the cars have fuel injection, and therefore electric pumps to provide gas instantly when starting, we have all become spoiled.

Having a carburetor rebuilt at a "rebuilder" usually means the carburetor is taken all apart and then soaked in a powerful cleaner solution.  Unfortunately, unless the parts are removed  promptly, the sealant on the cast metal parts of the float bowl gets removed by this process - that is why I recommend folks do their own rebuilds, or else buy one of the replacement AFBs from Summit Racing, PAW, or one of the other aftermarket suppliers of the Edlebrock clone of the famous AFB.

In your case, you could do a little detective work:  The following assumes you have this long cranking time only when the car has been parked for hours or more, not just a few minutes - right?  If so, notice whether you smell gas fumes under the hood when you come home from a drive and pull into the garage.  Open the hood (close the garage door to block out the wind) and wait a half hour or so, then go sniff around under the hood to see if you smell gas.  If so, it's evaporating out the top of the carburetor, or else seeping down into the intake manifold each time you park it.  This is bad for the car because it washes down the cylinder walls, and dilutes the engine oil with gas.   If this is the case, you should replace the carburetor - it probably cannot be fixed.  

To be complete here, there IS a simple way to avoid the starting delay, and that is to add an electric fuel pump in line with the mechanical fuel pump, which you would then turn on only when starting.  Be sure to wire it so it will not run unless the key is on, for safety reasons.  But to do the best thing  for your car, call up the folks at Summit or PAW and get their advice on which Edlebrock/Carter clone is right for your car - you'll be amazed at the improvement in idling, running, MPG and starting!

Dick