D-17 Running Rough, Backfiring, Flames Out Exhaust

Mowed with it last night and, about dark, it began running rough--kind of running rich (black smoke) and kind of missing (it seemed). I pulled the plugs, cleaned them (they are new). The were kind of black and sooty. The plugs had worked loose some. They were not tight when I removed them.

I pulled the carb and checked the float. It is fine. I had soldered it Sunday. It is not leaking. All seems okay with the carb I guess.

It will run rough and kind of miss. I checked the spark to each cylinder and each plug is getting power. I have not examined each plug when running though (guess I should do so). I checked the compression and it still seems very good.

If I let it sit and restart it, it will kick a flame out the exhaust. When I shut it off, sometimes it will backfire very loud.

Does anyone have any ideas of what might be going on with this old D17?

I will go out and check the plugs for spark. First, I will run it and check for a cool plug. Maybe a plug is bad. Thanks for any help.

I think it was the timing and/or possibly foulded or bad plugs. Also, I had adjusted the points. I ran it with the miss and then felt the plugs. The 2 rear were just warm, not hot. The front 2 were too hot to touch. I switched the rear 2 plug wires and it smoothed right out.

Had checked for an intake manifold leak and that was fine. I believe the carb is still working great. The gas level seems fine.

So, I mowed more with it. It is running better than ever. Seems to be fairly economical on gas--better than my Super MTA at least at the moment. I need to tune up the M some because it hasn't been done for years.

Thanks for all of the help from each and every one! I really enjoy operating this D17. It is really easy to mow with. The wide front and power steering are really great and it has plenty of power.

I have good luck with Champion Plugs.

• Hobby farm

• Hobby farm

It has a new condensor and points. There seems to be a spark there, but I'll check for a short. I think there is good clearance from the wires in the distributor, but I'll look again. I have seen spark with the tester I use at the plugs. I'll take another look at it. Thanks.

I'll rotate it around tomorrow and see what I have. I think I can kind of get the #1 piston up with the timing mark in place and check its reference to the distributor.

Once you have the screwdriver on top of the piston
slowly hand crank the engine and watch closely as the screwdriver rises and then stops. Your timing marks should be aligned too. Remove the distributor cap and see where the rotor is pointing. It should be at your No1 plug wire.
Both valves on No1 piston should be closed too.
Hal

I have had the gears on distrubutors wear out before (on cars). Is this the most likely possibility if it is a timing problem? Thanks.