How much play should my distributor rotor have?

My ignition is getting spotty. Starting hard, idling rough, skipping when I try to go to full throttle.

I pulled my distributor (model 9N12131) off of the front of the engine to take a look at it.

I haven't measured my point gap and such yet, but the first thing that jumped out at me is how sloppy the rotor feels.

It's hard to quantify; so I put a ruler next to the tip. I can move the tip 1/8", maybe a little more, without budging the shaft.

Is this normal? It's been a long, long time since I've taken apart an old fashioned distributor with a set of points and a rotor; so maybe I just don't have a feel for it.

Just seems sloppy to me.

Maybe barking up a wrong tree. I pushed down hard on the spring contact on top to simulate the distributor cap clamping down.

That seemed to tighten it up.

I have the FO-4 manual. I don't see specs for the coil in there. Can I take a resistance measurement of it while it's off of the tractor that would yield any information?

The contact in the top of the distributor cap, where it mates to the spring clip on the coil looks a little rusty and "burnt" (a little black around the edges) is that worth cleaning up?

Any general tips of what I should look for while this is off of the engine, other than the gap? The manual has a decent procedure for setting the gap and timing, but it doesn't describe common signs of wear and such.

"Have not checked points" --I bet it is the points--definitely the first thing I'd check.

Cleaning all the connections is time well spent. And free.
I would agree with Tom that points are likely the issue.

They too might just need a good cleaning if they can still be
gapped to the 15 thousands specified. Use a piece of card stock
or heavy brown paper like a paper bag. I use contact cleaner on
mine too when I have them off so they can be let dry.

Unless you have good test equipment it is hard to get a good
reading on a coil and even then it won't tell you what it reads
once it warms up. Hard starting doesn't sound like the typical
coil problem. They usually start Ok then quit when hot.

Lastcowboy32,Pull the rotor off of the shaft then shake the shaft side to side while looking and feeling for excessive side play in the bushings in both ends.If the rotor is still good shape and just loose on the shaft,just put a small piece of masking tape or even paper over the shaft to shim the rotor back tight again.Or get a new quality NAPA Standard Ignition #FD-71 Rotor,Points:NAPA #CS35 Standard Ignition Blue Streak #FD-6769X (Premium)Condenser Distributor Cap:NAPA #FA350. Don't waist your money on junk TSC or other such ignition parts.Also install all 4 gaskets new to keep moisture out.

cowboy.......yer 4-nipple squarecan front mount dizzy coil will read from the top terminal to the bottom terminal that goes to the points about 1-ohms; the other terminal will read about 4000-ohms that goes to yer rotor. CAUTION, even digital ohm meters can NOT tell you much more than that ...ie... continuity. What happens is the INTERNAL insulative tar MELTS and shorts out the coil in about 1-hr. Most coil problems are POINTS problems. The 4-nipple front mount ignition is designed to be removed and the points (0.015) adjusted on the kitchen table. Just un-snapple yer capple and remove the 2-bolts and walk. Installation is a reversal of the removal ...except... finger start the 2-bolts, install the ROTOR and ROTATE the ROTOR until the OFF-SET tang fits the camshaft slot. The OFF-SET scheme means you kenn NEVER install outta time. Now tighten yer 2-bolts and re-snapple yer capple. Simple, eh? REMEMBER to "polish" the INVISIBLE CORROSION from between the points (0.015) after installation. Me? I clamp the corner of $1-bill between the points and PULL. Iff'n yer really cheap, tear a strip from HEAVY brown paper grocery bag and use that........HTH, Dell, yer self-appointed sparkie-meister

" I don't see specs for the coil in there. "

That's because there aren't any.

All you will see w/ home equipment is resistance readings. Unless you see an open circuit or dead short, those readings don't tell you much.

It takes some very expensive equipment to test a coil.

" Starting hard, idling rough, skipping when I try to go to full throttle."

If you are 100% sure you have no movement in the shaft, the problem is likely in the points/timing. See tips 66, 67 & 68.

Using a jig from The Old Hokie makes setting the timing a lot easier. http://windyridgefarm.us/
75 Tips

Thanks for all of the tidbits.

The gaskets do look a little old and cracked.

No carbon tracking in the cap (I used to see that on my old '71 LeMans...loved that car...but the distributor was always a problem)

My FO-4 manual didn't give any tips for cleaning...I'll tidy up my points and other contacts.

Will probably take a little bit of experimentation and putting the distributor on and off a couple of times to get rid of the skipping, but at least I have a few things to try.

I want to get the old girl starting clean and running smoothly. Winter is upon us, and my wife loves the old tractor's simplicity. It's about the only tractor that she likes to use to clean the barn.

Thanks.

(quoted from post at 07:04:43 11/02/15) " I don't see specs for the coil in there. "

That's because there aren't any.

All you will see w/ home equipment is resistance readings. Unless you see an open circuit or dead short, those readings don't tell you much.

It takes some very expensive equipment to test a coil.

" Starting hard, idling rough, skipping when I try to go to full throttle."

If you are 100% sure you have no movement in the shaft, the problem is likely in the points/timing. See tips 66, 67 & 68.

Using a jig from The Old Hokie makes setting the timing a lot easier. http://windyridgefarm.us/
75 Tips

Click to expand...

I see that tip #68 mentions bushings as a problematic source of movement. The next chance I get, I'll check for movement without the rotor on and see how much of the "play" that I feel is bushings; because the points, condenser and such all look just about brand new (I've only had this machine a year). I'm not sure what was replaced when or how old any of the parts are, but I will check for wiggle in the bushings while I'm cleaning contacts and such.

" I'll check for movement without the rotor "

Excellent idea. If it moves at all, time for new bushings.

" because the points, condenser and such all look just about brand new"

If the points have a plastic rubbing block, just go ahead & replace them now, rather than in January at 10*. In the snow. Don't worry about the condenser.

If you replace the rotor, also replace the cap & get both from the same vendor.

Don't file the points. Just run some card stock or brown paper through them. If they are pitted/burned, replace them.
75 Tips

(quoted from post at 13:29:11 11/02/15) " I'll check for movement without the rotor "

Excellent idea. If it moves at all, time for new bushings.

" because the points, condenser and such all look just about brand new"

If the points have a plastic rubbing block, just go ahead & replace them now, rather than in January at 10*. In the snow. Don't worry about the condenser.

If you replace the rotor, also replace the cap & get both from the same vendor.

Don't file the points. Just run some card stock or brown paper through them. If they are pitted/burned, replace them.
75 Tips

Click to expand...

Well, I saw a thread titled "TSC Strikes Again." Maybe I should put this there. I tried the dollar bill trick to clean the points. I checked my gap. I checked my timing. I cleaned the contact at the top of the distributor cap (where it meets the coil) and reassembled.

I did get the old girl to start; which is better than it was, but it was still spotty.

There is a TSC right on my way to work. I'm pressed for time back and forth; so I figured..."what the hell?" I go in and find a complete tuneup kit: plugs, points, condenser, distributor cap, and rotor for 36 bucks. Why not? My plugs look ancient too. I know they're cheap parts, but it's one stop, and I can shotgun the whole shebang with the kit.

One problem, I get out to my car and open up the box. Wrong rotor. The rotor that they put in there doesn't have the tall spring clip on it that mine does. Everything else looks right.

So...I go back in...I bought the last kit. The only way to get the right rotor was by getting a smaller kit with just points, condenser and rotor.

Shoot me...but I don't have time to run around here there and everywhere...I rewarded their incompetence by getting the second kit just to make sure that I have the right rotor.

So now, I have an extra set of points and condenser for next spring

One of these days, I'll get ahead of the game and buy parts ahead of time, instead of when the tractor is down (I have another one...but I hate being down to one tractor). Maybe then, I'll have the time to forego the cheap knockoffs at TSC...but for now? I cross my fingers.

" Maybe then, I'll have the time to forego the cheap knockoffs at TSC...but for now? I cross my fingers."

Why not just order them now? Get them here from this site or nnalert's.

Points, plugs, condenser, rotor & all gaskets, about $20 IIRC. And, they are quality parts.
75 Tips