Jubilee

I am working on a jubilee, tractor was setting outside for about 15 years with no use. I had the head rebuilt, replaced rings and bearings, the sleeves looked great so I did not replace them. all new gauges, replaced the muffler and exhaust, converted it to 12 volt with alternator, new wires, plugs, even put in a hotter burning plug, etc. rebuilt the carb. However no matter what I do the plugs are very sooted up and it will start to miss after about 1 hour or so of running. I have leaned out the carb. as much as I can, and reduced the fuel flow, still no change. When I got the tractor the carb. was not on it. The only thing I did not do was check the intake for dirt dobbers, to see if the have plugged the intake. I cleaned the air breather and replaced the screen in it. It runs very good and idles well, you would not know the plugs are not getting enough air or too much gas. I even put a new carb. (marvel Scheibier) on it and the same thing is happening. I don't have enough hair to be pulling it out, but I am about to. Any suggestions? Thanks

You did a lot of things that could have waited to be done instead of just replacing a whole lot at one time. Rookie mistake #1 is to start replacing old parts with new until you test to see if old are defective. How do you rebuild a head? Should have taken block to a qualified shop and have them boil it and then tell you what all you would need, and probably able to supply you with whole kit. How do you tell by a visual inspection if sleeves are good or bad? You went thru all that work and now may have to pull block a second time. Next, what is the Marvel-Schebler Carb you are using -what is the model number on the brass ID tag -should start with 'TSX' ...no matter what I do the plugs are very sooted up and it will start to miss after about 1 hour or so of running.... Is it a popping sound or backfiring or both? How do you do your 12V switch over job? Explain details on what you did. You don't mention the distributor; was it tuned up and timed correctly with a timing light?

Tim Daley(MI)

Avant 1735, when I am overhauling an engine I do it all at once, instead of piece-mealing a little here and a little there, and when I take a head to the automotive machine shop we may call it getting it "rebuilt". I wouldn't call you a "rookie" since you have to have a fair amount of mechanic experience in order to think of undertaking the job. I wonder though how you "leaned out the carb" and "reduced the fuel flow". The small screw on the MS is low speed air. Turn out to lean it. The high speed big screw is out to richen, in to lean, but it doesn't come into play until you have a load on the motor. The way to reduce fuel flow into the air flow to it is to lower the float valve setting so that the valve closes at a lower level of gas in the float bowl. Is this what you did?

A weak spark can also cause fouled plugs. When you did your 12 volt conversion, did you put on a 12 volt coil or keep the 6 volt with a resister in series? Another test you could do is bypass the ignition switch. It could be going bad.

OK, here is the Paul Harvey, this rest of the story. I am no good at this so you will have to excuse me. I got the tractor running before any major work was completed, and found that 3 plugs had oil deposits after running a short time and the tractor had very little power. At this point I took the head into a reputable machine shop they cleaned/boiled the head and they replaced every replaceable part on it. So I replaced the rings, the pistons had very little carbon buildup on them, I also replaced the bearings. I decided to replace the carb that had been rebuilt because the air/fuel mixture screw was not working, there was no change in engine rpm's no matter how it was adjusted. The person who rebuilt the carb has done this for many years. I took the carb off several time each time cleaning it to make sure no trash had entered the fuel system. Then I decided to but a new carb. This one was working properly and after several times adjusting, there is still something wrong, as I said earlier after about 1-2 hours running time it starts to miss. I pull the plugs and they are black with carbon, not oil. So I am stuck as to why this is happening. I did put a 12 volt coil on it. I am sure I left something else out of this narrative, not intensionally. Thanks for your patience