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: Gerald : Thanks for the support. I have rechecked the gap a second time and it looks ok. The TO-30 shop book I have says that the dwell for that tractor is 30'. I thought it would be good if I could check it on my TO-35. But have been unable to find that info anywhere. I guess it will be ok without me checking it. Thanks again for the lesson. My next job is to check the timing but on the TO-35 it seems to be a little more difficult than checking it on my car or truck.
: Regards,
: Bob
: : : Like I said I am new to this stuff dwell, timing advance -- it almost sounds the same. Anyway what I am after is the dwell for the TO-35. Then I guess the next step is to check the timing. : : : Thanks for the support. : : : Bob : : : : : The TO-20 & TO-30 manuals I have says dwell should be checked to make the points do not burn it shows dwell at 30'@ 450 rpm etc. 20' @ 1200rpm etc. They say this should be checked to make sure the advance is working correctly. : : : : : Since I am new to all of this should I not worry if I do not check the dwell?? I did set the points and have rechecked and they are at .022. : : Dwell is the percentage of time the points are closed. It should not change significantly with engine speed. Unless the point gap is set with an allen wrench through a little door in the side of the distributor cap (ala General Motors vehicles of the 70s) its often not specified. Dwell is set purely by setting the point gap. : : Timing IS critical to engine operation, but can't be set until point gap is set. Timing intentionally changes with engine speed because it takes a roughly fixed amount of time for the fire to spread through the combustion chamber, so the spark has to be advanced more the faster the engine is running. Otherwise the bang is still putting out power when the piston gets to the bottom of the power stroke and the exhaust valve opens. (Which can burn the exhaust valve if repeated enough times).
: : : : : Thanks for the help in advance. : : : : : : Just put new points in the TO-35 we are restoring and after sitting for 15 years it started on the second try. I want to check the dwell to make sure I have them set right. Does anyone know the correct dwell? : : : : Are you SURE the manual says dwell changes with engine speed and checking dwell checks the timing advance? That's not typical for a Delco distributor. I think you remember the manual incorrectly or its been written by an English literature major from central Africa who can't get an engine to run with helpers. : : : : Timing advance changes with engine speed and 20 degrees advance is a lot for low speed 30 degrees not unreasonable for high engine speeds. With the distributor firing 4 times for two turns of the crankshaft (one of the distributor shaft) I'd expect dwell to be about 50%. If measured as distributor degrees, I'd pretty much expect it to be close to 45 degress since the points open every 90 degrees. Last I remember doing it on my MF-135 with the continental engine was that the timing marks were on the flywheel, not the crankshaft pulley. Same timing light worked for me.
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