I have a 65 V8, 4v, C4, that sat covered for many years. I spent the summer getting it reconditioned for restarting and driving. It was running well since restarting in August, but the accelerator pump began leaking last week so I changed the diaphragm. It ran well for a day, but now when I start the car it is hard to start and runs very rough at low idle. It runs smooth when I hold the gas down, but at idle speed, the engine pulses (i.e., it almost stalls, then surges, almost stalls, then surges, etc.). The plugs, points, condenser, coil, & battery are all new. The only thing I haven't reconditioned/replaced was the carburetor, the alternator, and the voltage regulator, which I planned to do soon.

Any idea what is causing the rough idle and surging? Vacuum leak?


Thanks

John

 

Probably. You didn't say what carb you have but a vacuum leak is causing the vacuum to drop enough for the secondaries or power valve to open at idle. Time to rebuild the carb.

 

Could it be choke adjustment problem

 

It's a an original Ford 4v (aka Autolite 4100, I think).

I'll check the distributor-carburetor vacuum line this weekend and all the carb nuts, screws, and bolts for tightness, but it sounds like you're thinking the vac. leak is within the carb. Isn't there also a vac line from the trans to the intake manifold? Could this be a possible source of the problem? Just trying to cover all my bases and ease back into being an informed Sunday mechanic after many years of inactivity.

Yes, I think the choke could also be the culprit since the car has been stored for 9 years and I have found that a lot of components have deteriorated and have needed to be replaced. I ordered a carb rebuild kit last week, but would this include components for the choke mechanism (i.e., the spring) or do I need to replace the entire choke mechanism as a separate restoration?

Thanks for your advice.

John

 

check the needle and seat. could have some trash in it causing it to flood.