48 cub problems.

I bought a 48 farmall cub about 6 years ago as a basket case when I came home from Afghanistan. I have been piecing it back togeather for the last couple of years and almost have it going but am now stumped. I followed the timing instructions on a really good YouTube video when timing my mag after I had it rebuilt by an excellent old IH mechanic. I can't quite figure out if I have my timing set correctly.I noticed my governor drive gear was two teeth off of being timed correctly (was two teeth from match ing the punch marks on the gov drive gear and crank gear at TDC#1) so I corrected that. Got my mag timed to what I'm 100% sure it's on #1 TDC compression stroke. I checked this by pulling #1 spark plug as well as the engine side valve train cover to check Piston and valve positions. Tried cranking to see if it'd run after this and it smokes, but doesnt really fire. It almost acts like it wants to fire but kicks back as if it's backfiring. Could it be I have the mag advanced too much? One thing that concerns me is when I crank the engine around to TDC again by hand with the kill switch off, I hear the mag "snap" twice. The guy on the video I watched said this means my governor is off 180 degrees. I dont see how this is possible though because both oth the small center punch marks on my governor drive line up with the gear that drives it from the crank. The timing mark on the crank pulley also lines up properly with #1 TDC mark. Does it sound like things are ok timing wise? I know I have spark because I've tested it and it has plenty of spark. I also have some work on the carb to get done setting the needle valve and float. Please help. -Ben

farmallcub.com is a good place for info on cubs

good luck
Ron

If you followed the timing procedure in the manual, you should be fine. A quick thumbnail is as follows: #1 piston on TDC on the compression stroke. with the mag cap off, make sure rotor is pointing just before #1. mag should slip right on, with the slots lined up. Turn slightly and the impulse should click. tighten her down and you are ready to go.

Like I said, this is a brief thumbnail. If the impulse is clicking twice, then there is an issue in the impulse. Did you try pull starting it? Also, did you have the cam out? You may be timed correctly to the govenor/mag, but is the cam timed right to the crank? Worst case, take the head off, and watch the valves and pistons. Also note the timing mark on the front pulley.

Keep us posted and let us know the progress.

1-3-4-2 going clockwise on the cap as your looking at the plug wire side of the cap, right? If you go counter clockwise is sounds and acts just like you describe.

I don't know if this is like the A I'm working on now but mine was off 180 and spitting out the intake of the carb. 1 tdc is intake and 1 tdc is compression. Make sure pressure is coming out #1 spark plug hole when piston is coming up.

It does almost sound to me like it's 180 off - as somebody else mentioned.

But if you're sure it's not...

I'm not clear on what you actually mean by kicking back. It COULD be that you're trying to get it so exact on TDC that you're actually slightly ahead of it, and sparking before the piston's there. Don't be afraid to err on the side of being past TDC. That'll have the added benefit of preventing broken bones should you ever need to hand crank it!

I've seen people try to get super precise with the timing, and it's worth remembering that these things aren't race care engines. A degree or two here and there isn't going to matter in the least.

So assuming everything's ok on that side, I'd spray a little starter fluid into the carb while starting. If it runs at all, that's a pretty good indication that your timing/ignition is ok, and you might want to focus a little more on the carb.

Not 100% foolproof, but if you're not having luck now with it, it can give you an "educated guess" on where to go next.

PS. You said you got it when you came back from afghanistan. Assuming you were there in a military role, I'm sure I speak for everyone here when I say thank you for your service.

Ben, I re-read your post and I first off also want to add a double helping of "thanks for your service"

The Cam gear needs to be timed correctly to the crank, and then the govenor gear timed correctly to the Cam. IF you are sure that those are all correct, we can move on to the next item.

The mag impulse will "click" for each cylinder, not just #1. So, as each piston hits TDC, the mag impulse will "click". Since this is a 4 cylinder engine, that would be twice for each revolution. My comment about something being wrong with the impulse is NOT an accurate statement on my part. If it is "clicking" more than 2 times per revolution, then yes, something is wrong.

Last item, it is really hard to over advance a mag, not saying you can't, but if you do, it isn't much. if I remember correctly, there is only about 15 degrees of timing adjustment on a lateral mount H4/J4 mag (7 1/2 degrees each side of TDC). Rolling the mag towards the engine advances the timing. rolling away from the engine retards the timing (at least for CW rotation mags, diesel mags are CCW and don't apply for you J4 application).

You may not have the govenor drive gear timed correctly when veiwed from the rear the drive lugs must be at 8 and 2 you can call me anytime at 217 370 3286