Snowflite snowthrower No Spark

[hansgrego]

I have a 1985? MTD Snowflite That has no spark.
This Tecumseh engine has points and a magneto behind the fly wheel.
I replaced the points, the ignition module, removed the kill wire, but still nothing.
Is there a way to test the ignition module with an ohm meter to see if perhaps I purchased a bad ignition module?
would I expect the two smaller wires to show no resistance on an ohm meter.?
Spark plug wire to ground shows 8k ohms, the previous ignition module showed 5.6k
I did have the magneto off previously, but I believe I have the gap correctly set to .012 (about a business card thickness away from the magnets).
I can hold a screwdriver up to the magnets and the magnets attract the screwdriver at about 3/4 inch.

 

[Rivets]

Primary resistance on the old coils was 0-15 ohms. Secondary resistance was 12,000-15,000 ohms. If you removed the magneto from the engine, without marking it first, the ignition timing is probably off. The timing is very critical on the old Tecumseh engines. This manual will give you the procedure to do so, but you need a special dial indicator to do so. Most of todays shops don’t know how to do it and don’t have the indicator. https://www.mymowerparts.com/pdf/Te...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf

 

[hansgrego]

Thanks for the reply. I did read about using the tool to get the timeing correct on the motor.(after I had removed the magneto).
I've seen others on other forums say just set the magneto in the center of the mounting posts.

I would think it would still generate a spark even if the timeing is off though.

 

[Rivets]

Many times you can get spark, but not always, as centering magneto means very little. I’ve done a couple hundred of these ignition systems and I’ll bet less than 50% of the time I. Get it right the first time. It depends on quality of the coil, cam wear, good condenser and points. Remember you are talking a few thousands of an inch. There is no air gap measurement. Believe it or not, it normally takes me 2 hours to get it right, when I get a case where someone has tried before me. Good luck, or find an old fart to help you out. Any one younger than 50 has no idea what we are talking about.

 

[hansgrego]

I must have saw the magneto air gap on a youtube channel... Now that I know that no spark may just mean that the timeing is off I won't throw more parts at the motor. My other problem is that I'm not sure what motor is on the snowblower... No tags that I can find on it.
G054B (or is it 6054B) doesn't match any Tecumseh motors when I search. Thanks for your help

 

[Rivets]

Numbers are stamped into the top or side of the shroud on most older Tecumseh engines.

 

[marsh94312]

To time it without special gauge.... Remove head, place straightedge across cylinder hole and bring piston up---in right direction--- and place .050" feeler gage between piston and straightedge. When you get that right you can set your point gap to about .017" and you will be in time. This scheme, and measurements, work on the old Tecumseh's I've worked on. You can use the ohmmeter to get the make and break just right. Time consuming but works. Good luck.

 

[marsh94312]

To time it without special gauge.... Remove head, place straightedge across cylinder hole and bring piston up---in right direction--- and place .050" feeler gage between piston and straightedge. When you get that right you can set your point gap to about .017" and you will be in time. This scheme, and measurements, work on the old Tecumseh's I've worked on. You can use the ohmmeter to get the make and break just right. Time consuming but works. Good luck.

Something I forgot. The timing plate is also involved and that is tricky. The plate position, the points spacing and the .050" piston spacing are all going on at the same time. Set piston spacing first, then the points spacing and then fiddle endlessly with the timing plate under the points. You will use words I'm sure you never knew.

 

[Rivets]

That procedure may work, but you are forgetting two things when setting the measurement BTDC. One, measurements vary from .035”-.090”, depending on engine model. Two, you don’t take into account the head gasket thickness, when compressed. If you figure out these two measurements and have the appropriate feeler gages, it should work if you have the time and patience.