solution to hard starting - got spark and gas.

[rick 48 cub]

Hi All

I would appreciate any advice that any of you experienced cub owners can share to help me overcome the hard starting problem.

I am a very new owner of a 1948, magneto charged, 6 volt, cub tractor. I get a good white spark, and there seems to be plenty of fuel. I keep installing new spark plugs (Champion D18Y) because they keep turning black.

I can only get it to start with EXTENDED cranking (with a 12 volt jump) with very little throttle. (Choke does not seem to matter)

Thanks

[John *.?-!.* cub owner]

A good healthy mag spark should jump 3/8 to 1/2 inch and be blue. Might als check carb to manifold gasket, and manifold to block gaskets.

[Bigdog]

Check and re-set (if necessary) the point gap and then set the timing according to the owner's manual. That should help some. Then consider re-building the carb and making sure the float level is correct. It sounds like it is too rich.

[Eugene]

Magneto. You should hear the impulse coupling snap when cranking the engine. Try cranking the engine by hand and listen for the click/snap.

The impulse coupling retards the spark during cranking (under 150 RPM)to TDC. Without the impulse coupling the magnito will fire in the full advanced position.

and ditto the previous posts.

Eugene

[beaconlight]

White spark? should be blue.

Bill

[beaconlight]

Once you have good spark and gas you need the spark at the right time. The spark should be when the piston just reaches the top (highest) point of it's travel. This is called "TOP DEAD CENTER (TDC) Once the engine is running some what faster than idle the spark is before TDC. With a magneto has an impulse coupling built into it. This accomplishes the above. When the spark is at TDC it is call retarded and causing the timeng to change before TDC is called advancing the spark. This change in the time the spark occurs is called timing the engine.
From far away it seems to me that you have probably have two problems. The first is the white spark (weak spark)and the other is that your carburator has a problem causing too much gas because of the black plugs you mention. I have this feeling about the gas because you don't mention the black as oiley.
Your level of knowledge of engines is the thing we need to know in order to best help you. It is possible to give so detailed an explaination as to insult your intelligance. And if your knowledge is not great it is possible to give not sufficiently detailed as to be of no help.
There is a manual on timing magnetos have you it and read it?
Let us know where to start and some one will respond withwhat will help you best .

Bill

[Carm]

Do not forget about the wires, make sure they are not resistor core. That is what was on mine wnen I bought it.

[Lurker Carl]

Make sure the choke rod at the dash is actually opening and closing the choke plate in the carburetor! The clamp on the choke shaft is prone to slipping.

[rick 48 cub]

Thanks for the help - I think I am going to start with the Mag - it appears that my 1/8" white/weak spark may be the problem. Rick

[Bigdog]

If that's all the spark you have, that is definitely a problem.