Compression CAT D47U Pony Motor

That's probably about it, but it should run. I have dealt with one that is worn so bad, the dipstick jumps up and down when it runs, but it runs and cranks the diesel just fine.

Try swapping the plug wires in the cap on the mag. Those ponies are an even fire design, so you can only be right or 180* off.

If that doesn't help, how about some new spark plugs?

I have 40 and 70 in my pony cylinders and it runs on that low compression

thanks for the input, it helps to know I'm not pursuing a lost cause. Regarding spark plugs, they are new. After a lack of success with the plugs out of the box (and gapped at various gaps between .20 and .50), I "side gapped" them, i.e. I ground off the part of the positive electrode to the edge of the negative electrode, to provide the fuel air mixture better access to the spark. I've been playing with the timing (via point gap) which seems to make a bit of difference, time to play the carb again.

it does sound like a fuel supply issue. the new owner of my old 9u phoned me the other day saying the pony starts then dies instantly. turned out the fuel line was plugged from the pony tank to shut off valve. Points should be clean as a whistle, i remove my ponts and clean them in my little shop, then re-install them and set the gap to about 0.012" to 0.014" (if i don't have a manual telling me the exact adjustment), this may not be the correct adjustment as per the manual but it usually generates a good spark. i use the NGK AB6 plugs, i haven't had any luck with the champion plugs. NAPA carries the NGK plugs at my local dealers.

the fuel should run out of the line full flow at the carb. if it trickles, it will fill the bowl enough to start but quickly runs out of fuel and the engine dies.

60 psi of compression isn't awesome, but i have had one pony that had about 35 psi on one side and 15 psi compression on the other side and it ran well enough to start the main.

Ditto, unless your fuel tank has been redone or replaced, they rust an plug up the system as I have learned. Pleasures of running old equipment.

G

Nothing like the sound of a sweet running pony in the morning. The hard part is getting it to run sweet. :biggrin1:. Only kidding you guys. Seriously, they can be a pain in the rear, but I just love them too death. I guess I'm just "Old School and nothing but a fool". :nod:
J. Giraud
40' Cat D2/3J#4103
41' Dodge WC-12 1/2 ton Military 4x4 Pick-up

Is the starter turning it over fast enough?