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TomF

A real mind bender for the old hands!

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TomF
Here's one that had us stumped. We've solved it, but the symptoms still don't quite add up. Maybe you have an idea: One of our A-C Big Tens refused to run. She wouldn't fire at all. We were getting spark when tested with a spark tester between the wire and plug. OK there, we thought. Then we'd crank 'er over, but the spark plug would remain bone dry. No gas, it seemed. We checked the fuel line, filter, etc. Fine all the way to the carb. Checked the entire carb out and all the passageways appeared open. Why aren't we getting gas? I dumped a teaspoon of gas into the cylinder, turned it over, and not even a puff or cough!? Huh? AH-HA! It must be the plug is bad! Put in a new plug, and VOILA! She runs! Put the old plug back in, and the plug remains bone dry and the engine non-running. Could this be a compression relief related thing? Or a weird plug that burns gas without exploding? Any ideas? Tom

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dlcentral
Other than the apparent bad plug you could possibly check the int vlv. [common on B&S.] lost it's clearance! Check BOTH vlvs for proper clearances!And head gask. for leaks too.Does it backfire out the muffler or air intake when running?Or make a 'chirping' sound[bad head gask.] when running?

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BradW
If it is a champion plug you are using,you are asking for trouble, they foul out easy and don't really have the right "heat setting", I recomend autolite as that is what they came from the factory with. Just a thought-BradW

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TomF
Dave, we haven't had any backfires or chirping when it's running. And we've never done any work on valves before. Where does one start on checking valve clearances and what is the objective? Would it be in our B&S L-head service manual? I'm guessing it is without looking. Thanks for spending time on our "puzzler"! Tom

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KenW
Hmmmm..a good one. Just finished something similar on my tractor. Model 725 with a briggs mod 19. Couldn't get it to start...rebuilt carb and new points plugs. Put gas in cylinder but would not turn over. Pulled plug and grounded base but had good spark. Put plug back in and held wire away from tip of plug and had a spark jump about 1/2 inch but then it started to cough and sputter...first signs of life. Also got good bite even through insulated pliers. Put wire back on and no life. What was different when it sputtered??? .........I was holding the plug wire away from the engine housing so the plug wire was leaking. I believe the wire and coil are one piece units so rather than changing it I got a wire sleeve in black ( TRAK auto, comes in all sorts of colors to trick up the inside of cars). Cut to size and it jumped to life on the first crank. Easiest starting tractor I ever had...now. Good luck...Ken Williams

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