I have recently rebuilt an old style Atomic 4 engine (dole recirculating thermostat, round tranny cover, etc.). Everything was taken apart, cleaned, painted and replaced as necessary. It starts quickly and runs smoothly at about 1200 or so (by the ear), after the choke is open. But, suddenly after 20 to 50 seconds it drops to a rough 600 or so rpm, and stays there. The engine will rev up, but roughly. A hot restart will be at the rough 600. A cold restart goes through the 1200 smooth to 600 rough switch after 20-50 seconds.
Everything on the fuel and electric side have been changed:
The carb is a new Zenith from Moyer
The fuel pump is a new low-pressure electric with filter
The fuel is straight connect from a remote outboard motor tank
The distributor is a Prestolite with electronic ignition, and it was traded out
for one with points and condenser.
The cap, rotor, wires and plugs are new.
The coil is a Flamethrower for electronic ignition, and it was changed out for
a new one.
The batteries have automatic charger and are at 13.4 volts.
The engine does not eject water when cold, and the Dole thermostat was
cleaned and tested ok.
The prop shaft does not turn in neutral when the engine is running, but
does go to reverse when asked to.
Both the owner and I are at a loss for what is changing the operation of the engine. It is predictable, in that it happens every time, and is consistent in its results or affect on the engine operationally. Any suggestions would be appreciated.
David
Everything on the fuel and electric side have been changed:
The carb is a new Zenith from Moyer
The fuel pump is a new low-pressure electric with filter
The fuel is straight connect from a remote outboard motor tank
The distributor is a Prestolite with electronic ignition, and it was traded out
for one with points and condenser.
The cap, rotor, wires and plugs are new.
The coil is a Flamethrower for electronic ignition, and it was changed out for
a new one.
The batteries have automatic charger and are at 13.4 volts.
The engine does not eject water when cold, and the Dole thermostat was
cleaned and tested ok.
The prop shaft does not turn in neutral when the engine is running, but
does go to reverse when asked to.
Both the owner and I are at a loss for what is changing the operation of the engine. It is predictable, in that it happens every time, and is consistent in its results or affect on the engine operationally. Any suggestions would be appreciated.
David
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