85 HP Cutting Out Bad

burly

burly

Senior Member
Guy's the 1939 85 hp has started cutting out bad. It will start and idle fine but when you mash down on the gas or hold it to the floor it sounds like somebody beating a drum. So far I've changed condensor, coil, resistor, carb, filed and re-set points. It appears to be getting plenty of gas. Poured marvel oil down the carb thinking a valve may have been sticking but to no avail. When under power it will just smother out like you've cut the switch off or ran out of gas. I haven't replaced the points as of yet but thats about all that left. Just wondered if you fellows might have any suggestions you'd be willing to share. Thanks!
 
Sounds like somethings plugged up in gas line or carb.Have you checked the flex hose at the pump. ken ct.
 
Just a shot on the dark, but I had a car years ago that did the same thing...discovered that points gap had definitely "closed up" (I don't like filing points...too cheap to replace). If you're getting plenty of fuel (important to check not only pressure, but also volume), sounds like it has to be an ignition problem. You didn't mention plugs, although I can't see all of them not firing at the "same time". Does this happen cold and/or hot? Did it start doing this "overnight"?
 
Ken, I've unhooked the line from the carb and cranked it over and it's really sqirting the gas out. I pulled the 94 off and bolted a recently rebuilt 97 on, same results?
 
Yeah, It started suddenly but seems to have gradually gotten worse. I don't like filing points either but had the dizzy off and a 3 day wait for new points to arrive. Thought I'd give it a shot,
 
I'm not trying to get smart with you or belittle you in any way,BUT---We had a 50 Ford pickup with your same symptoms.Would only run 35mph in third gear.The problem turned out to be an old glasspack muffler that the lining had the flow blocked.We put it on my lift,knocked off the muffler,threw it in the dumpster,then went for a ride.I shut it down at an indicated 85mph.That was the problem.Hope this helps. James
 
I would also check your plugs and wires. If you have a weak spark you can still get a cylinder to fire under a light load. When you try a heavier load like speeding up the engine, the cylinder(s) cut out. Are you getting a good blue spark that will jump a 1/4 inch gap to your spark plugs?

If you have good spark it also might be the main circuit in the carburetors are both clogged. If you have working idle circuits but not main circuits you get the described problem too.
 
Blow the fuel line back into the tank, could be partly clogged and restricting FULL flow. Been their, did a new carb, then pump, then fuel line, then a new tank and no problem since.
 
Burly,
Try the new points as soon as they arrive....NAPA and Carquest
usually have them overnight....I just finished a Flathead tuneup that had
me frustrated....a new set of points installed elsewhere were floating after
about 30 mph. The spring tension was so weak the points could not follow
the dist cam. By a process of elimination I finally found out the new set of
made in China points were NG.
Charlie ny
 
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