I'll try to eliminate all the ideas so I'll list what I have tried but first a little history.
1976 MTD 990 16 HP B&S model 326431
* When first purchased low to no spark due to bent points push rod & damaged cam lobe.
* Installed Nova II module tractor ran very good no problems at all.
* Dismantled tractor to rebuild, repair, sand blast & paint.
* I never removed the flywheel.
* When I installed the coil I put three layers of painters tape between the coil & Magnet because of no business card handy.
* First time start up last week, hard to start, back fired a few times but started several times & ran well.
* Tried a few days later but wouldn't start just backfired through muffler a few times.
* Rebuilt carb still won't start. While turning over I open & close fuel/air mixture valve, when I get around 2 1/2 turns out it starts back firing again. When I turn it to 1 1/2 turns out no back fire.
* I have hot blue spark
* Full tank of gas (990 owners know about having no less than 2/3rds tank)
* Float level was adjusted to level when turned upside down.
* Gas in carb.
* Plenty of compression.
* I can see the intake valve going up & down as normal.
* Pulled the exhaust pipe off & could see the exhaust valve stem going up & down as normal.
* When I pulled the spark plug it looked dry not flooded as expected concerning the amount of gas in carb.
* I put a few drops of gas in the intake then put the plug back on & it back fired a few times then nothing still wouldn't start.
* I blocked the drive shaft & tried to turn the engine at the pulley in the front to see if a pin had sheared.
* I have two concerns about what I done:
1. When I installed the carb there was no gasket between the cylinder & metal plate. The only gasket is the thick one between the carb & manifold pipe.
2. Could the three layers of painters tape be a problem instead of the typical gauge of a business card?
My thoughts are what would keep a large amount of gas to not be in the cylinder head area when I removed the plug. I made sure I cleaned everything & air blasted all openings when I rebuilt the carb. Maybe I'll take the carb off & clean again to make sure I have no blockage. If I haven't sheared a key & didn't remove the flywheel is there something else that could cause the timing to be off.
I wanted to rebuild this engine later but not now because it ran so well before. I wanted to get some seat time on this for awhile. It may not run but it sure is perdy. Any help please it would be greatly appreciated. I have exhausted everything I know to do.
If you need to research anything here is my rebuild. I warn you it's lengthy.