I need help with injector timing--3 cylinder diesel

I will try to keep this as short as possible. Anyway, I acquired a 3 cylinder Long 510 diesel. The previous owner had taken the injector pump and a few parts off, but it was supposedly a running tractor that they stole parts off for another tractor. The engine is a Fiat design that is used in a lot of tractors such as White, Allis Chalmers, Hesston, etc.

Had the injector pump and injectors rebuilt. Got everything installed, bled down, etc. but can't get it to start.

Here is the problem. Somehow, the prior owner moved one of the gears so the timing marks were off. I figured out how to get it close, but there is no way to do it according to the manual without taking the entire tractor apart. Seems the engine is part of the "frame" so to remove the front cover and pan,you would have to tear off a lot of stuff.

I can fairly easily change the timing position of the injector gear. Also it is unlikely that the main timing gears to the crankshaft were moved since that was not disassembled. The gear that they moved only drives the fuel pump, but the timing mark is hard to get back to where it is correct.

So far, the best idea I have is to change the timing one tooth at a time on the injector pump and try to get it to fire. But there are a lot of teeth and nothing has worked so far. It is definitely getting fuel and lots of smoke. It will momentarily fire on ether, but will not continue running. I'm fairly certain it is just a timing issue.

Is there a shortcut to finding the correct timing? I have the manual and have read how to set it up, but that would involve a whole day of work to take the front of the tractor apart.

I would appreciate any ideas on how to get this timing issue solved.

Remove the valve cover and no. 1 injector. turn engine til the exhaust valve on no. 1 cylinder just closes and intake starts to open. Turn engine one more revolution and use a pick or brass welding rod to get piston on TDC. Turn injection pump by hand in the direction it normally turns til fuel comes out the no. 1 port. Back pump up to where fuel started to come out the port and you will be within a tooth or two. Mark the gear that drives the pump and the pump gear so you can find your starting point. You may have to move it a tooth or two, but should run so you can tell which way to move it. I've done it this way a couple of times and could at least get it to run.

Try Dave's idea first, you already tried mine- reaching under the timing gear casing and moving the teeth a few at a time? I had a project just as bad- a Standard diesel in a MF35, British engines rarely have timing marks, just a manual with navigation points, this point at 45 degrees while the other at 9 o'clock... with #4 valve stems at whatever... what a trip! But she started on her own after quite alot of poking... but with starting fluid... and alot of priming, purging..
Hey that isn't a CAV injector pump is it? With the letters on a barrel in there to adjust timing??? Have a look in there, might be the same idea no mater who made it. You'll see what I mean.. good luck.

I tried everything Dave suggested. Plus, I spent at least 6 hours just moving the injector timing gear a couple of teeth at a time. Still no start. It will fire on ether, but not continue running.

Then I went to a local tractor repair shop and talked with John, one of the best mechanics around. He suggested almost what Dave said, and added that I might take the cover off the side of the injector pump and look at setting "A". That is the only thing I didn't do because it has a seal and small cable from the rebuilder. Don't want to void the warranty!!

I did verify that the flywheel was on TDC after both valves opened and closed and another revolution was made. This is supposed to be where it fires. Then rotated the injector pump to where fuel comes out of number 1 and set it at that point. Still no fire.

Help, I am out of options (and patience).