Can't start MD on gas after overhaul

It would sure be nice if this project would go in my favor for once...

I had disassembled the engine to replace the cracked block, and while I had it tore apart new sleeves, rings, and bearings were installed. Now I have reassembled everything and set the
starting linkages to spec, but I cant even get the engine to pop once.

I have never heard this tractor run before, and I was fairly certain after checking for "spark, fuel, compression, timing" that it would pop right off.

The mag puts out a good blue spark, and is timed to the "M" mark on the crankshaft pulley. Cylinder #1 fires at TDC of its compression stroke. Good fuel flow to the carb. I even changed
out the entire intake manifold and carb assembly from a running MD and it made no difference. So this makes my think that the problem may be in the magneto.....

Engine has very good compression on the gas side, I can hardly hank crank it. This is how I would test the mag to see if there is spark, and the impulse trips. I use the starter when
actually trying to start it.

I had the cylinders well oiled when I assembled it, and there is a white fog/smoke that comes out of the exhaust after I attempt to start it (burnt oil I assume??).

Any ideas on what you may think needs to be checked? I'm leaning towards the magneto, but it sparks at hand-crank speed on all 4 plugs (Champion D89D extended tip).

Thank you!

Are the plugs firing order correct? 1342 counterclockwise rotation on the mag.

Never operated one of those but white smoke to me idicates the diesel side is not shut off. Are you sure you have the gas/diesel levers positioned correctly for gas starting? Disconnect a couple of the lines from the injectors and see if they are delivering fuel while cranking. If so something is wrong. What do the plugs look like? If they are dry I would try dumping a tablespoon or so of gas in their holes then crank with the starter and see if it fires. Do this to #1 & 2 since you are pretty certain you have #1 timed properly. Leave the injector lines disconnected for this test. Have you run one of these switchover IHs before? Not a flame, just curious. I know if I was in your shoes I would be thinking I am missing something due to no experience with the odd set up. As Jim said the distributor rotation is backward from a straight gas burner. Good luck.

(quoted from post at 13:20:15 01/05/17) Are the plugs firing order correct? 1342 counterclockwise rotation on the mag.

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Yes, I knew about the CCW rotation of the mag and the firing order is 1-3-4-2.

I will look at the timing marks on the rotor pinion and the distributor gear.

Might just add that the distributor rotation is checked by looking at it from the back past the oil filter. Again not a flame just want to make double certain we are all on the same page.

The decompression lever is forward (gas side). I've come to learn about how the entire system works and I find it fascinating.

I'm trying to get it to run on gas so I can bleed the final fuel filter and the injectors. I wouldn't think that there could be diesel making it to the injection pump yet by just cranking the tractor. I have the diesel throttle as far off as possible. The throttle lever at the pump can move about 3 inches, so I don't believe the rack is stuck.

I'm going to work on it all day today. Thanks for the input so far guys!

Yes, CCW looking from the oil filter.

For giggles crack the bleeder screws at the
injectors and crank it over. If fuel is
squirting out then the rack or plunger is
stuck.

Pull the plugs and put a squirt or two of gasoline in each hole. Put the plugs back in and start it. If it runs and stalls, you know it is fuel delivery. If it does not even pop, the issue is either spark timing, or butterfly opening. Have you checked to see if there is carb suction at the carb intake when cranking? Jim

Check the timing on the distributor/mag. When I put my smd back together had the same no start senerio, minus the white smoke. I eventually loosened the distributor and adjusted while cranking the engine. Very slight adjustment and it started right up. I think the gas start diesels are less forgiving of timing that is perhaps not spot on.

Nothing but air coming out at the injectors at this time.

Yes the butterfly valves are closing, and there is definitely suction at the air intake.

I've removed the spark plugs multiple times and they are wet with gas, and so is the chamber in the head.

Should there be an audible sound coming from the impulse on mag when cranking with the starter? I can definately hear it when cranking by hand.

I'll give it another look over. The mag was snapping right at the "M" mark on the pulley.

I was wondering if when the tractor was cranked by the starter that the magneto would advance prematurely...could there be something broken or missing in the mag?

So your getting fuel into each cylinder. Assuming that your valve timing is correct and the spark timing is correct.... go to that running MD and swap out the magnetos. See what happens then. I had a mag that fired great on #1. But it had a bad cap and wouldn't fire correctly everywhere else.

So swap out mags. Make sure both tractors are set on #1 top dead center during the swap and when you swap back to you don't screw up the running MD.

(quoted from post at 14:31:29 01/06/17) So your getting fuel into each cylinder. Assuming that your valve timing is correct and the spark timing is correct.... go to that running MD and swap out the magnetos. See what happens then. I had a mag that fired great on #1. But it had a bad cap and wouldn't fire correctly everywhere else.

So swap out mags. Make sure both tractors are set on #1 top dead center during the swap and when you swap back to you don't screw up the running MD.

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I would do that, but the other tractor has battery ignition....