Cleaning & gapping lower spark plugs

8/13/16, Tach: 91.6, Hobbs:102.2

Cleaned and gapped 4 bottom spark plugs since the engine has gotten harder to start. This difficulty to start (now when cold) seemed to occur right after re-setting the timing to 25 BTC on each mag. On the prior maintenance, i noticed the timing had drifted to 27 BTC on one mag, and 29 BTC on other mag. Resetting this to 25 & 25 did make an appreciable difference in lowering my CHTs (TODO: find dates & download before/after logs).

I borrowed Adrian’s gap measuring tool (TODO: buy), and all 4 plugs were worn (or were never originally set) to gaps larger than 0.022. The acceptable range is 0.016 to 0.021. Some folks have said plugs wear 0.001 to 0.002 in 100 hours. This would seem to indicate mine were not gapped to start with or they wore very fast.

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