Running on one cylinder

620rookie

Member
Today I installed Petronix ignition and "Flamethrower " coil on my recently purchased 620T. Some of you may have seen my post last week where I whined about my poor performance at a pull. I've never been very confident about ignition issues, so I was elated when I followed the instructions and the tractor actually started afterward. It ran rough and backfired a time or two, which I attributed to needing a timing adjustment. About this time, a friend who is much more knowledgable about JD's showed up and said, "it's only running on one cylinder". To prove his point, he took a pair of pliers and pulled the plug wire off the R hand plug, and nothing changed about how it ran. I had already planned to change plugs and wires, which we did, to no avail. I knew that plugs sometimes don't perform well under compression, so we removed the plug, reattached the wire, and ran the tractor as my friend grounded the plug against the frame, and saw no fire onthe plug. With the plug out, the tractor seemed to produce significant compression out the plug hole, indicating the valves seemed to be functioning. Keep in mind that the tractor has performed and sounded like it does now since I bought it a month ago, so this is not related to the new electronic ignition I installed today. I didn't have time to buy a new distributor cap today, but checked the old one with a meter and it showed conductivity to both posts. Any suggestions?
 
Carb is plugged up on that side. Do yourself a favor and dig
down in the coin purse and have it professionally rebuilt by a
reputable co. I'm sure there are several but Farmers Services
re manufactured my 60 carb. The visible quality of the work is
apparent and the great performance is even better. It's not just
cleaned there, it's re manufactured. Even though my 38 B runs
pretty good now, as soon as the tractor shows and plow days
wind down, Mr Farmer is getting that dtlx 10 to work his magic
on.
 
Oops I see you don't have fire lol. Do you have the correct cap for your distributor? It's a common occurrence that people are sold the incorrect cap for their particular 2 cyldistributor/tractor and it will exhibit your symptom of one cylinder no fire condition. Everything I waxed on about the carbs still stands though haha
 
Are you running solid core or regular 7 mm automotive wires? When I put my electronic ignition in my 720 LP, I fought a miss in it too. I found it one evening with it running after dark and I could see the spark jumping right through the plug boot! I put a set of 7mm automotive wires on it and the problem went away. Just a thought.
 
(quoted from post at 21:47:01 10/14/14) The new wires are stainless steel with silicone jackets. I haven't seen it run in the dark though.

As previously pointed out. The 620 gasser needs the offset distributor cap, not the even spaced cap.
 
If you move the dead plug to the other side does it fire? If it fires move the wire to the other side and see if you still fire. If the wire and plug work get a cap and rotor. I had a 50 once that drove me nuts running onone cylinder. It turned out the screws had come out of one of the choke butterflies and the choke plate was sucked up against the venturi shutting off most of the air to that cylinder.
 
You have to get down to the basics and get to where the correct sides plug is firing when its cylinder is at TDC. Have you tried swapping plugs and wires to insure neither of those are the problem???

Try getting the left cylinder up to TDC on its compression power stroke and then with dist cap removed see if the rotating leading magnet is just at the fixed pick up coil (that's like when old poinst opened) and see if the rotor tip is lined up (if cap was on there) with one of the distributor cap towers that leads to the plug wire to that cylinder. Then rotate the engine 180 degrees at which time the right cylinder should be at TDC on its compression power stroke at which time the rotating trailing magnet should line up with the fixed pick up coil and the rotor tip is then lined up with where the cap tower is that leads to the right cylinder if it were on there.

Could be a timing problem or a cap or rotor problem.

John T
 
Did this start with the electronic ign.? sometimes they pack the wrong pickup coil and it fires 180* . I have run into this several times .
 
The poster said:

"Keep in mind that the tractor has performed and sounded like it does now since I bought it a month ago, so this is not related to the new electronic ignition I installed today."
 
Hay Earl, Your answer goes along with my concerns below. If the distributor cap or rotor or the elec ignition is out of sync he may be firing No 1 where number two is supposed to be and number two isn't firing. I will be seeing Jimmy again, but not until after Christmas.

John T
 
Are you sure you have the right dist
cap?
I think the 620 has the verticle
dist and uses a different cap than a
horizontal, someone correct me if
I'm wrong
 
Thanks to everyone who posted comments while I was at work today. In answer,let me say that we tried switching wires and plugs with the same outcome each time. I am waiting for the arrival of a new cap and rotor on Friday. In the meantime, my friend brought a cap from his G, and it performed exactly like mine. What I have not tried, and won't be able to until Saturday, is manually moving the motor through the cycle and correlating the ignition with the pistons. It does seem likely that when the #2 cylinder should be firing, it isn't in the correct configuration inside the dist. cap to do so. By the way, my distributor lays horizontally, protruding from the side of the engine housing, not vertically as some folks have implied. Were 620's built with both types? Thanks again for all the advice. A local acquaintance has implied that the problem could be inside , involving the dist. drive gear, etc. I can't feature how anything related to conducting the impulse from the electronic module to the plug could go deeper than the mounting plate in the distributor base, could it? Perhaps someone had the distributor out and reinstalled it 90 degrees out of phase? Is that physically possible?
 
Are you sure your tractor is a 620? If it has the same distributor as a G it sounds as though it is a 60. Are the spark plugs in the block or in the head? No 620's had a horizontal distributor. All were vertical and camshaft driven. Mike
 
The plug is in the edge of the block, angled toward the head. The distributor is definitely horizontal. Would 620 sheet metal fit on a 60? It has no serial plate. Maybe it's a 60 in disguise.
 

iirc there were a few odd ball all fuel export 20 and 30 series tractors with mags that were horizontal and were driven at crankshaft rpms?
 
I believe you are right, Glen. Spark plugs in the block pretty much
confirms that his tractor is not a 620, though. Mike
 

I agree.
Even after we have all seen a 1st numbered series painted with 20 series yellow stripes and decals at shows and auctions. It took a long time for anybody to consider the possibility that this 620 was a decoyed 60.
 
Interestingly enough, it does have an all fuel dash, with markings 'G', 'F', and 'O'. However, it only has one tank, and the knob through the dash now is a fuel shutoff, not a selector. Without a serial #, how else could I tell if it was one of these oddball 620's you refer to? It doesn't have the fancy 620 seat, but I just assumed someone had replaced it with the battery box type at some point.
 
(quoted from post at 20:09:42 10/16/14) Interestingly enough, it does have an all fuel dash, with markings 'G', 'F', and 'O'. However, it only has one tank, and the knob through the dash now is a fuel shutoff, not a selector. Without a serial #, how else could I tell if it was one of these oddball 620's you refer to? It doesn't have the fancy 620 seat, but I just assumed someone had replaced it with the battery box type at some point.

We need some images. The sparkplugs in the block seals the deal on it being a 60.
 
Here are some pics. I'm confident now that it's a 60, not a 620. Shame on me for not doing my homework. I still want to make it a pulling tractor .
mvphoto12070.jpg
 
Very definitely a 60. And from the picture it appears the serial number tag was up top under the distributor. That makes it a very early model, if my eyes are seeing the picture right. Mike
 

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