1951 Cub won't start after sitting 3 Months

[FamilyCub]

I last started my Cub in April. I tried stating it a couple days ago...no luck. I could smell gas so I checked for spark...none! I tracked the problem back to the coil. Replaced the coil and installed new points and condenser while I had the Magneto apart. (The Tractor has new plugs and wires installed last winter...Autolite 3116 gapped at .025 and copper core wires)

I checked again and all four plugs have good spark but the tractor still won't start. I can smell gas on the plugs but they are not covered or dripping gas. So, I am thinking I have some carb problem. I put a rebuilt carb (IH) from Steiner's on the tractor last winter. Subsequently, I didn't think initially the problem was carb related since I could smell gas on the plugs.

Any help would be greatly appreciated!

[staninlowerAL]

You referenced a magneto, and from the description sounds like you might have an external coil instead of a mag coil. Did you install the rotor and pinion with the timing marks correctly matched? Did you set the points gap to .013 or .020? Did you have anything else other than the mag opened up to install the points? What type ignition switch do you have, battery type or original kill switch to the magneto?

[Don McCombs]

Have you checked for good fuel flow from the fuel cap to the carburetor fuel inlet screen?

[FamilyCub]

Hi staninlowerAL,

Apologies, I have an internal mag coil. I set the point gap at .013. I checked that the timing marks on the rotor and drive gear were aligned per manual during reassembly. During disassembly I followed instructions for removal--i.e. rotated the engine until the impulse snapped and the rotor was pointing at #1 on the distributor cap. The tractor has a kill switch with a single wire from switch to external lug on the magneto. I also tested the kill switch. Other than pulling the spark plugs, I did not have anything else apart.

Thanks!
~ Smitty

[FamilyCub]

Hi Don McCombs,

I have not checked the fuel flow yet but I will do that. I did notice later that I had some gas dripping out the bottom of the carb.

Thanks for your help!
~ Smitty

[staninlowerAL]

Your description of working on the mag sounds right and you have spark at the plugs seems like the ignition side is OK. Don's comment on fuel flow and you saw fuel dripping seems reasonable. I would remove the carb drain and catch a quart or so to check full unrestricted flow, then check the main jet for any obstruction. If you have to open the carb, you can check the idle jet. The only other thing I can think of is not enough suction to pull the fuel into the cylinders. Sometimes one or more valves can stick, especially if sitting for a while. A bit more trouble to check but probably worth it if the other things check out. Compression test will tell pretty quick.

[Gary Dotson]

Cranking an engine with no spark can easily fuel foul the plugs. You might do well to pull them and have a look.

[FamilyCub]

HI Gary,

I pulled all four plugs and grounded them on the engine. I have good spark with all four. It appears to me that I am not getting fuel into the cylinders. I can smell gas on the plugs but they are not very wet. I hope to start checking fuel delivery from the carb to cylinders today. I am getting gas to the carb because it is dripping out the bottom (which is another issue to look at) when the fuel valve is open. Thanks for your suggestion!

~ Smitty

[FamilyCub]

Good Morning! Started checking things out again and found the tractor 180' out of time, which would certainly not let it run. However, the spark may burn off some of the gas in the cylinders, which would explain why I was not showing much gas on the plugs.

I pulled the distributor plate off and found the drive gear and rotor misaligned.

When I put it together yesterday I made sure the gears were aligned with the alignment marks.

I started looking at the drive gear and noticed that the collar is worn.

I also noticed that the drive gear can move some distance (maybe 1/8" to 3/16") before it hits the gear cover. I never had occasion to work on this gear before. Is this wear on the drive gear normal or too much? Is the drive gear supposed to have 1/8" to 3/16" travel through the distributor plate?

Thanks for your help!
~ Smitty

[FamilyCub]

I ordered a new pinion gear. It should be here in a couple days. I decided to replace the rotor at the same time. It shows a little wear but no teeth are missing, worn down, etc.

Thanks!
~ Smitty