TO30 popping

I just got my TO30 going after years of being last on the list,started quickly,idled within seconds, 20 PSI oil pressure. It warmed up, thermostat opened and everything sounds good. I had my head shaved,new valves, guides,seals and seats touched up.I set the valves .015 cold and checked them a dozen times.The carburator was soaked,blown out and rebuilt. Carb set to factory spec.The only problem is when I rev it I'm getting an intermitant popping that I haven't been able to solve.It seemed to be starving for fuel but I couldn't adjust it out. I messed with timing to no effect.Reset the timing to spec. Removed bowl drain and had decent flow I thought. A test ride wont let me load the engine at all. I pulled the carb bowl and thought the level was wrong. After adjusting and starting it seemed better. Slowly throttling up,no popping. Took it for a test ride but the pop returned. When I got to the garage I started messing with the carb setting again and discovered that I can screw the air fuel mixture screw all the way in when machine is idling and it has no effect. Again,the tractor starts instantly and idles sweet. Clogged air fuel needle orafice effecting main jet setting? Thanks, Mike
 
Sounds like a bad manifold leak with no change in air mixture, try spraying carb cleaner around to find but take care that engine is not warmed up.
 
Have you replaced the points and condenser? If so, try the original condenser. New condensers are notorious for being bad out of the box. Also how is the distributor? Any side play in the shaft? Any wear will cause the points to not stay set as the shaft moves side to side. Also be sure the centrifugal advance is free and springs back when released. If not, the distributor will need to come out, cleaned up, repaired and reinstalled. Finally check the spark quality AT THE PLUGS. Needs a good solid spark that will jump 1/4".

I know you don't want to open the valve cover again, but a rhythmic popping back through the carb under load is a symptom of an exhaust valve not fully opening, as in a flat cam lobe. If the problem persists, that would be something to check. Watch the valves with the cover off. Be sure all appear to open equally.

One other thing to check, the air cleaner. Try a test run with it disconnected. It may be clogged with mouse nests, dirt dobbers... There is also a wire mesh inside the canister that is often neglected.

Now, look at the carb adjustments again.

The small screw up by the throttle shaft is the idle mixture screw.

It operates backward of what most are used to. The screw adjusts air bleed, not fuel, and it only effects idle. With the engine up to operating temp (it does have a thermostat installed?) and the idle RPM down around 400-500. Slowly back the screw out about 1 1/2 to 3 turns off the seat. When the idle starts to stumble, it is getting too lean, turn it back in to best idle. If the engine will not idle down that slow without dying, (providing the rest of the engine is healthy and spark is right) the idle circuit is clogged or sucking air where the bowl meets the top cover. If the idle screw still has no effect, the idle air bleed orifice is clogged.

Now to the main adjustment. This is the large screw on top of the top cover, or on bottom of the bowl, depending on the design. Again with the engine up to temp, start with the screw about 3 turns off the seat.

Set the engine RPM to full governed speed. Manually pull the governor link back to idle, (watch out for the belt!) let the engine wind down, and release the governor. The throttle should instantly go to wide open position. as the RPM come up, the the throttle should return to near closed. (If the throttle does not respond this way, there is a problem with the governor adjustment.)

What you are looking for is the engine response under sudden throttle. Keep repeating the test, turning the main screw in 1/4 turn before each test. When the engine hesitates, it's getting too lean. Keep repeating the test, this time backing the screw out 1/4 turn. When the engine responds without hesitation, the mix is correct. A single puff of black smoke is the goal.


Let us know...
 
What type fuel are you using ? My Ferguson TO-30 always had a popping sound at idle I started using non ethanol high octane gas and what a difference
starts better and seems like it has more power.

A bit on the costly side but well worth it ..
 

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