More J4 mag Questions ???

Thu Nov 11, 2004 8:21 am

I'm trying to get a 49 cub running the PO did some crazy stuff that I wont go into. My questions are...

1. The wire coming from the coil inside the mag where does it go? Does it fasten to the post that the condenser/kill switch goes to, or does it go to the other side of the points???

2. On the rotor botton and the other small gear there are marks I assume that these are timing marks.. If this is the case it looks as if there are only 2 possible ways to put this back together? The correct way would be to get #1 cylinder at TDC then make sure that the rotor button is pointing to the #1 wire on the distributor cap??? the other way would put it 180 out ???

3. Yesterday I bought a 56 model cub and it is the distributor type setup the motor has no compression at all (haven't really got into it yet) so my thought is to take the motor from the 49 that is in rough shape and put it in the 56 that is really nice, once I get it running. What is the better of the two setups the distributor or the mag setup???? What other problems am I going to get into if I do this???

I'm new to the Farmall cub thing but have been into the Cub Cadets for several years and thought it was time to get me a big cub... Will post some pic's once I get the posting process figured out....

Thu Nov 11, 2004 8:51 am

Toolman. On the home page here, read Chauvin's tips for timing and stuff. Good info. I'll try to answer your questions:

1. Without taking mine apart to be sure, it goes on the inside post that goes thru to the kill switch.
2. You are correct about the 180 degrees. To be sure, take #1 plug out and put your thumb over the plug hole and rotate the engine till you feel air pressure. This is the compression stroke. Line up the mark on the pulley with the timing pointer and the mag should trip exactly there. This is TDC. Your points should point to #1 post on the cap.
3. Some people think the mag is more simple and more reliable. Others think battery ignition is more efficient. This would be the choice of the owner. Which ever you prefer.

Hope this helps. And, guys, chime in on my errors..........

Thu Nov 11, 2004 9:09 am

Confirming what Ron L said.
1- wire goes under same bolt as kill switch.
2- if you get it wrong simply rotate the mag shaft one round (1 round of mag = 1/2 round of rotor).
3- Mag versus battery ignition is just a matter of personal preference. Coils and parts are cheaper for batttery ignition, but a mag will run with a dead battery. Before doing the work changing, check valves. They may be sticking and easy to fix. If it's underslung exhaust make sure it isn't plugged with mouse nest, etc. Not common, but cna happen. Not being able to push out exhaust will cause it to not draw in mixture to compress.

Thu Nov 11, 2004 9:27 am

squirt a little marvel mystery oil in each cylinder of the '56. roll the motor over a few times and let it sit a day. then see it you have compression. the rings might just be stuck from lack of use.

a rebuilt mag will give years of good service and does not require a battery, generator, etc. to operate. a friend of mine has a cub with NO starter, generator, battery,battery box, lights, or hydraulics. original from the factory that way.

you can always swap to the distributer for a test on the 49. just put 6 volts neg to it.

the rotor should point at about 8 oclock with everything timed correct. then go clockwise in setting the plug wires. 1-3-4-2

Thu Nov 11, 2004 10:23 am


What the other fellas said is great advise.
One other thing,
On the small gear in the mag there's a pointer mark. This mark should be lined up with the casting mark on the rotor. 8)

Thu Nov 11, 2004 3:59 pm

Hey Guys thanks for the help!!! The 49 is among the living.. It runs but has some carb issues but sounds like it is a good strong engine...with no smoke YEEEHAWWWW!!!!!

I also got the 56 off the trailer and into the garage and messed with it a little I pulled the valve cover and sure enough it has some real sticky valves/ lifters. Everything looks real clean from what I can see. I think to be on the safe side I'm going to pull the head and have a look see inside.. Got to put in an order for some gaskets and carb kits it looks like.. I might just have two running Cubs after all,, time will tell !!!! Good Cub Day!!!!

Thu Nov 11, 2004 5:25 pm

One more note, if the wire going to the mag coil from the points was disconnected when you bought it there is a good posibility the internal coil is bad and that an external coil was being used in it's place.

Thu Nov 11, 2004 7:50 pm

Toolman. Isn't it great to hear the old engine roar! If you decide to get a carb rebuild kit, don't go cheap. Get an IH - p/n 354454R92. Heard many horror stories involving the cheap ones. Also, check out LC's "Carb how to" on Rudi's site at the link below. Excellent tips. ... index.html
Keep us informed on your progress.............