|
Congratulation Matt, Good Job. Im not much of a D man, so take this for whats its worth, but that popping out the carbs intake and pressurizing the air cleaner may be caused by at least one of the cylinders firing (exploding creating pressure) out/past the intake valve (which leads through the manifold to the carbs intake and air cleaner), probably cuz its sticking and/or not sealing properly or not adjusted (lash too tight) right not allowing it to close completely. Out of time can cause such things, but if it started and ran it cant be extremely out of time. Also, if the choke isnt working right or the carbs float or for some other reason like you flooded her bad, theres an accumulation of raw fuel lying in the manifold or carb, it can ignite and cause that back pressure you mentioned. You should get gas vapor out the petcock, and if you get a lot of pure gas, youre flooding her which can cause problems once the plugs eventually fire. The proper initial start up timing is when the left hand (flywheel side) cylinder is at Top Dead Center (TDC) on its compression power stroke, the Left Hand Impulse timign mark on the flywheel should be in the 3 o clock position and just passsing by the flat horizontal mark on the tractors side. If you have the plugs removed for easy flywheel turning, you should hear the mag and plug fire just as the flywheel is rotated past that mark at 3 o clock. If she fires too soon before then (too far advanced timing) the flywheel may kick back, but if too far after then (timing slow retarted) its harder to start. Even though Im not much an a D, I will venture a guess that one cyliner has a leaky or sticking intake valve or its lash adjustment is set too tight not allowing it to close and seal properly, so when the fuel charge explodes, it blows hot gas pressure and heat through the carb to the air cleaner. Have you taken a look at the valve lash clearances????? One of the intake valves may be set way too close/tight. You may have some carb or choke and timing problems also, but check the intake valves (including lash clearance) and let us know what you find. If one of the cylinders has a leaky intake valve, when you turn her by hand up on compression on that cylinder (disconenct plugs so she dotn start) it may be detectable by the presure escaping out backwards through the carb. (Take off air pipe and look and listen) You might be able to see the vapor and/or hear if compression is leaking back through the carb. Also, a compression check on a cylinder with a leaky valve will be way less than the other cylinder assuming its valves are okay. Good luck with the old girl. John T Nordhoff in Indiana
|
