Need help awakening a B

[Darwin]

I am trying to help a friend get his 73 B running after years of sitting.

So far we have draind the gas, gave it new plugs, points, cap, and rotor.

The air pump was forzen up so we removed all of the emmision equipment.

The SU HIF-4's have been rebuilt and set as close as I can get them by ear. No sync tool.

Timing has been set to spec.

Now for the problem:

The car idles very roughly and will backfire through the exhaust. At higher RPM's it runs real strong. It will backfire as you let off the gas.

Anybody got any ideas as to what to look for??

Thanks

Darwin

 

[Bob Claffie]

First thing I would look for is an air leak somewhere around the carbs/intake manifold. Second thing would be to check the float levels in the carbs. Sounds like the ignition is OK. Bob

 

[aeronca65t]

....and see if it's running on all four. Pull one plug wire off at a time while it's running (and set to fast-idle). Removing the plug wire of a "dead cylinder" will leave the idle speed unchanged. Use an insulated ignition pliers or similar tool to do this (unless you have a strong heart!).
If one cylinder is dead, you may want to do a compression test and investigate further.
With all the years sitting, it may have a sticky valve. Sometimes, a few hours of moderate running and several oil changes will help to unstick a valve.