Dave's 1650 Project

[westofb]

I still stand by my confirmed statement, I agree with Matt that you could be a tooth off in either direction and still get them to open as the s mark moved into the window. However, if you cam was in wrong, one tooth off, you would have one of two senarios. One tooth off in one direction would have the points rod riding on the baseline of the cam load, to get it to break in this senario, your points would constantly be open, since you are on the baseline of the lobe, they would have no choice but to be open. The second senario is that when you set them to open as the s mark moved into the window, you would already be up on the lobe of the cam (they are already starting to open before reaching the s mark), this might be hard to tell, but as the cam follower dropped back down on to the base line of the cam, you would have slack between the follower and points themselves. So if you were off in this senario, it would be hard to see slack in the follower/ points, so maybe you could be off in one direction, but I would think you could detect the slack between the follower and points if you were to look closely (may have to use a magnifying glass).

So Matt could be right if you off one tooth in the second senario, just for the fact that detecting the slack between the follower and points would be tough. In the first senario, you would never get the points to close because you set them to open on the cam lobes baseline or base circle. I hope this makes sense.

[CC1650Dave]

It's funny I'm second-guessing myself on the cam/crank matching. I'm sure I got it right but this whole mess just picks at your brain.

[Matt G.]

Originally Posted by westofb

One tooth off in one direction would have the points rod riding on the baseline of the cam load, to get it to break in this senario, your points would constantly be open, since you are on the baseline of the lobe, they would have no choice but to be open.

It sounds like you are saying the points would always be open. They won't...they'll be off the same 5ish degrees the cam is off, but they will still open and close normally. There is so much adjustment range available in the points that you could still set them to break when the "S" mark is in the sight hole.

Originally Posted by westofb

The second senario is that when you set them to open as the s mark moved into the window, you would already be up on the lobe of the cam (they are already starting to open before reaching the s mark), this might be hard to tell, but as the cam follower dropped back down on to the base line of the cam, you would have slack between the follower and points themselves. So if you were off in this senario, it would be hard to see slack in the follower/ points, so maybe you could be off in one direction, but I would think you could detect the slack between the follower and points if you were to look closely (may have to use a magnifying glass).

There cannot be 'slack' between the points, rod, and cam under any circumstances. The spring in the points keeps the pushrod in contact with the points and cam. If it was floating, you wouldn't be able to run the engine, let alone time it.

Heck, take the crank out, and the cam, pushrod, and points will still operate the same way...

[Matt G.]

Originally Posted by CC1650Dave

Yeah, the plug is new and properly gapped. I can't remember the brand I'm using, but it's the one that everyone here likes. Maybe it was an Autolite 216, or 261? Something like that.

Regarding this fuel test you do, what kind of ratio are you mixing this fuel? That's the main thing that has made me hold off on it.

The plug wire, condenser and ignition switch are next. After that, I'll swap the coil and see. Beyond that, the only thing I could do is replace the points (they're new aftermarket, came with the kit) with some Kohler points.

Mix it to whatever 2-cycle ratio you like. 40:1, 50:1, etc. Just use some of the mixed fuel from your chainsaw or week whacker. It may not even be all that critical, but this is how my dad has always done it, and neither of us has lost an engine as a result. Any amount of 2-cycle oil mixed in there is going to be better than raw gas, at any rate.

Before you start troubleshooting electrical components, simply visually check for strong blue spark at the plug. If you have that, the coil, condenser, wire, plug, etc are all fine and you have some other problem.

[pulse301]

Originally Posted by Matt G.

Before you start troubleshooting electrical components, simply visually check for strong blue spark at the plug. If you have that, the coil, condenser, wire, plug, etc are all fine and you have some other problem.

Not trying to play devils advocate, but just want to share an experience I had with my case 222. It has the same engine and ignition switch as the 1250. I was having problems getting the tractor to start, the engine would shake pretty rough, sometimes it would actually start, but would shake rough and finally die. When I pulled the plug to see if it had spark, it actually did, and it was a strong blue like Matt describes. BUT, when I'd put the plug back in, the engine would get flooded or run extremely rough if it did fire, and die. It turned out, one of the wire connecting to the ignition switch was pretty dirty and EXTREMELY loose. What was interesting, when I would take the spark plug out, the spark was perfect, because the air in the engine could escape the plug hole, and not shake the tractor. But when i would put the plug back in, the engine was shaking enough to make the wire wiggle, and would short out against the wire next to it. I only noticed it when I tried firing it up in the dark one night, and a spark caught my eye coming from behind the ignition switch. In all honesty, you're probably safe if you have the blue spark, but I know from experience now that the blue spark doesn't guarantee no electrical problems, haha.

[westofb]

If the points will always close and put tension on the cam follower, then how would they ever open to start with? When you are setting the points, you are setting the base of the points as the stopping point, as the follower comes up on the lobe it is pushing the spring loaded part of the points away from the fixed base. But I guess I am missing something, your the cub/ kohler guru around here, I guess I have no idea what I am talking about.

[Sugarmaker]

Dave,
Watching from over here in NW PA. We are here for you!
Regards,
Chris

[Matt G.]

Originally Posted by westofb

When you are setting the points, you are setting the base of the points as the stopping point, as the follower comes up on the lobe it is pushing the spring loaded part of the points away from the fixed base.

Now that's correct...I think I misinterpreted your previous post, and then wasn't seeing it quite correctly in my mind. Yes, once the points are closed the pushrod is floating in there. But still, it wouldn't matter, as that situation still exists whether you have the cam properly timed to the crank, or off a tooth. The points lobe is an eccentric circle, which I think results in more uniform motion of the points plunger (the lobe for the fuel pump is the same way, probably for the same reason) and like I said before, there is so much adjustment range that it won't matter. You can set the points to be open all the time, closed all the time, and anything in between. All you are doing by changing the fixed point is adjusting the angle the cam is at when the points open, so as a result you could compensate for the cam being off a couple teeth and therefore not be able to ascertain whether or not the crank/cam are timed to each other correctly.

I think we are beating a dead horse at this point anyway, since I thought Dave posted pictures of his correctly-aligned timing marks. Or am I thinking of someone else?

[Methos]

Wouldn't pulling the head and bringing it to TDC and checking the site hole and seeing T stamp mean that the cam and crank are timed correctly?

[Oak]

Dave, if you pull the fuel line off the carb do you get good flow from the tank? Maybe jump 12 volts to the coil to to bypass any problems in the ignition circuit like Pulse said. Try another Autilite 216 plug. WTF this thing should run.