Topic: Wont go over 50 when hot.


Dick    -- 06-02-2011 @ 4:41 AM
  Drove the 41 V8 the other day. Ran great for the first couple miles then starting to skip through the gears and wouldn't go over 50-55. Was 90 out that day. Temp gauge was in the middle do it wasn't over heating. Skip did the coil and the water pumps so I can't figure whats wrong. Let it cool off for a while and it ran fine. Any ideas?


alanwoodieman    -- 06-02-2011 @ 5:16 AM
  what kind of gas? I have found that the ethanol blended gas causes this and have use some that has no ethanol. Another thought is the fuel pump pressure, but this can be related to the gas


supereal    -- 06-02-2011 @ 6:58 AM
  I'd suspect a fuel delivery problem. It could be as simple as a gas cap that is not providing sufficient venting, to a fuel line between the tank and the firewall that is partially clogged with rust and dirt. We are finding that the copper coating of the fuel line is attacked by the alcohol in nearly all fuels. As you have covered the usual coil problems with a good rebuild, I'd do a fuel pressure and delivery quantity test. Good pressure doesn't always mean adequate supply.


Dick    -- 06-02-2011 @ 3:03 PM
  Thanks supereal & alan Will check these ideas.


37RAGTOPMAN    -- 06-02-2011 @ 5:52 PM
  Check the resister, seems to me if it only act up when hot, if might be the resister,or condensor,I would check, them as well as the fuel output as other recommended..
my 3 cents 37RAGTOPMAN


drkbp    -- 06-03-2011 @ 5:42 AM
  Dick,

After you check the more likely fuel causes the others have given, I would put another 2-screw coil on just to confirm it's not the coil and condenser. I wouldn't think it is the coil but I don't go far without a spare coil and condenser anyway. Heat can cause the coil to act up.

The little adaptor setups the vendors have for the three and two screw coils let you use a regular condenser and a regular 6-volt coil with the internal resistor. If either the coil, condenser or resistor foul up, that adaptor "replaces" them all and you get home where you can sort it out.

Let us know what happens. Pretty car. My aunt bought a cream colored one late in the year 1941 to get a good deal. Had a new car knee deep in tires for the whole war.

Ken in Texas


TomO    -- 06-03-2011 @ 8:53 AM
  A bad resistor or weak condenser will provide a weak spark when the engine is at normal operating temperature.

I agree with Supereal that it sounds more like a fuel delivery problem. Pulling out the choke part way can make the car run better, when you have this condition. You should check fuel delivery after you have run the engine for a few minutes at idle.


To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas.

Insufficient fuel delivery can be caused by a vacuum leak, plugged flex line, worn pivot in the pump arm, stretched diaphragm, plugged fuel line or tank pickup, plugged tank vent or wrong gas cap or a worn push rod. The push rod should be 8 7/8" long for the cast iron manifolds and 7 7/8" for the aluminum manifolds. It travel is about 3/8".

Check your fuel pump sediment bowl for rust. If you have the 41 style fuel pump, remove the top cover to check. The 47-48 pumps have the glass bowl and that gasket can leak due to drying out of the cork or over-tightening the clamp and distorting the housing.

Tom


supereal    -- 06-03-2011 @ 1:43 PM
  I agree with TomO. The resistor does get hot, but it is supposed to, as the heat increases resistance to keep the system voltage from burning up the coil. I think that you will find that your gas line from the tank is full of rust and dirt. We have seen too many, including my own '47. If the car can't get enough fuel, it won't run fast. The heat has little to do with it. If you get to 50 mph, it is hot, anyway.


Dick    -- 06-06-2011 @ 2:29 AM
  Haven't had a chance to check out the skipping but I took a long ride on Sunday to a car show. Took second. (Got beat out by a 37 Packard) and it ran perfect. Maybe if it aint broke. The 41 likes me now.


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