Strong spark - check.
Fuel - check
compression - ?
Before you do any major surgery, run a compression check on ALL cyls.
Remove all plugs and spin the engine to clear the cyl's of excess fuel then run the compression check.
These Stovebolts will start and run on 4 cyl's but highly unlikely on just 3.
You may find a couple valves that aren't closing, even after adjusting them previously, BTDT. check, recheck and recheck again but a compression check that only takes 5 minutes or so can narrow down cyl's with problems.
Good luck
Dave
