TEA 20 Timing Possibilities??

deermedo

New User
I have a Fergy that is acting up to say the least. It is running
part time terribly backfiring, coughing, choking and then
quits. The gen/regulator system is out of service so the only
electrics are the starter and battery and ignition. I have
sprayed gas into the back of the carb when running with no
results. There is about 1/16 of an inch slop in the distributor
shaft. This happened a few hours ago and we rotated the
distributor clockwise and it appeared to straighten right up for
a few hours running then back to spitting and quitting. Is it
possible for the distributor shaft to jump and throw the timing
out?
Any suggestions would be greatly appreciated as the
frustration level is at an all time high!
Thank you very much.
John
 
Very unlikely it 'jumped', but more likely the hold down bolts aren't keeping the shaft tightly bound in one spot.
Another possibility that I never ran into before buying my dead TEA, was that the top of the shaft had a notch of steel missing, yet the plastic rotor was fine. I guess this is all Lucas Electric designed, so we must ..... expect the unexpected....
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try replacing the condenser with one that is known to be good. Just because it is a new one doesn't mean it is any good.

Bob
 
Mine is ok Tony but I am still confused with the amount of slop in the distributor. When turning it over by hand the rotor has 3/4 of an inch slop between fire spots in the cap as well as better than 1/16 radially which affects point gap accuracy.
 
When my TEA 20 acted up I placed a socket on the head of the bolt that hold the pulley to the CRANKSHAFT . I turned the crankshaft Clockwise until the rotor started to move. I then turned the crankshaft counter clockwise until the rotor started to move and found that the TIMMING chain, and both the CAM sprocket and Crank sprocket had to be replaced. Once I opened up the front cover the GOVERNOR assembly also had to be replaced.
Bob......
 
Hey John
How did you determine the end result? Was there an amount the crank turned prior to rotor movement? Mine appears to move right away when I turn the and drive the crank in both directions???
 
At the end of a 12 inch ratchet,I noticed the ratchet would move 2" between Clockwise and counter clockwise before the rotor would move. The ROTOR DRIVE on my TEA 20 S#182991 (6 Volts)was sloppy and the rotor was starting to contact the CONTACT points inside the Distributor CAP. I replaced the BALL Bearing assembly (inside the distributor assembly) and the amount of side movement / slop of the rotor drive is now nothing.
On my second TEA 20 S#251562 the drive TANG on the end of the DITRIBUTOR shaft was so badly worn it would misfire. I have a TEA-20 FERGUSON made in England with a POSITIVE GROUND /6 Volts. The COIL has three connections, CENTER HIGH VOLTAGE LEAD to DIST., "SW" and "CB". SW.. Connected to 6 VOLTS supplied FROM IGNITION SWITCH and CB connected to CONTACT BREAKER in Distributor. INFO found in an original HARRY FERGUSON SERVICE MANUAL. With engine running/ operating there is 4 volts from "CB" available to contact Breaker in Distributor.
Please note. The DRIVE TANG on the end of the DISTRIBUTOR on all three of my TEA -20's is OFF CENTER. The drive key way on the GEAR DRIVE matting with the CAMSHAFT is also off center. There are several gentleman from the UK,Ireland,Austraila and the USA with more experience than I have...:)
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Please consider typing "TEA20 Back to life" in archives of this forum under the FERGUSON section and read all comments from "Griz/Bob (Aust)John(UK) and Tucker101
These gentleman seem to have a great handle on the TEA-20's
 


The symptoms you describe could be distributor related , another cause of these is a poor coil . Coils will sometimes operate well for a while then after heating start to break down and produce intermittent problems . Just to confuse the issue some will operate poorly when cold and improve once hot . It depends on how and where the coil has developed poor continuity .
Try substituting the coil and see if it solves the problem .
 
I see a couple of problems here...

A 1/16" slop in the distributor bushing is beyond worn out! No way the points can be properly set and expected to stay set with that much play. The solution would be repair or replace the distributor, or install an electronic conversion. Even with electronic, that is still a lot of play, at the least I would still disassemble the distributor, put in new bushings/bearings and go through the weights and springs to be sure they are working properly.

The other concern is the lack of a charging system. If it wan for hours without charging, you were literally on "borrowed time"! LOL
 
Hey Steve, The battery is fully charged and brand new so supply
voltage shouldn't be an issue. What blows me away is that it
starts and runs for about 20 seconds very well and then just
sputters and quits. I ran the gas out of the base of the Zenith
and there was a continual good flow.I even sprayed gas into the
back of the carb with no results. Timing chain slop?????
I am totally confused.
 
If you decide to service the DISTRIBUTOR here are some valuable steps. Pleases note the UNBELIEVABLE fix that someone had done to the mechanical advance........LOCK WIRE!.....This showed up when I installed the distributor on my test engine. My test engine has 145 teeth on the ring gear. 360 deg/145 = 2.48 deg per tooth. At 2600>2680 RPM of engine the TIMING was NOT 25 Deg (10 teeth) but rather O deg. The drive TANGS are ready to fail on another Dist. drive.Before you disassemble your distributor you may wish to read these instructions. Next time I shall try to obtain SEALED BEARINGS.
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Doesn't sound like a timing chain. You can "feel" the slack in the chain by hand turning the crank back and forth. Be sure it's in neutral, ignition off, grab the crank pulley and turn it one way, then turn it back the other way. Turn it back and forth a few times, you'll feel a loose area where you're taking up the slack in the chain. If it's less than about an inch of crank pulley diameter movement, it's ok.

Typical timing chain failure is no start at all, sounds like turning over with the plugs out. A stretched chain will cause lack of bottom end power but not sputtering.

I still think it's distributor related. Worn bushings allowing the points to go out of set. They will change with different RPM, temperature, etc. Once they have run out of proper setting, they tend to get burned.

If you get a dwell meter you can watch the point setting while it's running. If the meter stays steady where it's supposed to be, the setting is staying where it should. If the reading goes all over the place when the RPM changes, the shaft is moving side to side in the bushing.
 
Ok Steve heres another one for you if you should be so kind....The damn thing starts right away and runs well for 20 seconds and then sputters and coughs and quits. If it was a distributor issue would the time running be almost exactly the same every time or would it vary?
 
Worn distributors can do strange things. Need to do some diagnostics to know what's going on.

Have you checked the voltage to the coil while it's running? See if it drops when the problem occurs, maybe loose connection, bad ignition switch, failing resistor if it has one.

Try easing the coil wire out while it's running, just enough to make it arc, see if the running improves, watch and listen to the arc, see if it varies with the misfire.

The running without a charging system is still a factor. If it gets run that way on a regular basis, it's possible the points have been overheated. Points are sensitive. Anything abby-normal will shorten their life. As the voltage slowly goes down, the amperage draw across the points increases, thus causing overheating. The wear in the distributor will also overheat them, getting too close will cause arcing instead of a clean break, too wide will cause weak spark, not enough dwell time.

Another diagnostic is try pulling the choke out a little, see if that improves the running. That would indicate lean mixture.
 
Hi Steve,
Just to clarify a few things the tractor was being brought into the shop for a new regulator as the old one was rotten and this is when it started to act up. All the electrics were removed and the coil, ignition switch, points,condenser and battery were replaced. It did this one time in the past this summer and when we turned the distributor clockwise a fair amount it straightened right out for a few hours. When it starts it runs great for 20 seconds and then starts to backfire and run very rich. Pulling the choke will keep it going but barely.
Thanks John
 
Pulling the choke will keep it going but barely.
Thanks John

A classic diagnostic for eliminating electrical problems from fuel .
Pulling the choke as a measure to keep it going points to a fuel starvation problem .
 

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