Halleluja! Another believer in less timing can equal better mileage. Setting the timing to occur later can generate more pressure when the piston has greater mechanical advantage over the crank.Over the years of tuning I have found that slightly retarding the timing as the MAP decreases and rpm rises helps keep you in a MPG sweet spot.
It only takes a few degrees too many and and it only took a couple of days of light driving to do it. The heater core was getting plugged so I wasn't getting much heat. We were having a cold spell and I was buried with outside projects. So I added a couple of degrees more advance to the spark timing in the 30-50 kPa range at cruise rpm on the highway to try and generate a little more heat in the head. Second day after the changes, I stop at the end of the exit ramp, and the low oil pressure light turns on. The car had run for a year with no trouble and now, with a couple degrees more advance, I had to replace the rod bearings. I might still have them... the upper halves have nice, shiny spots where they should be dull gray. Pulled spark back out, installed new bearings (and larger oil pump since I was in there) and ran for several years before pulling the engine and dumping the body when it rusted out.I have never seen anyone hammer bearings, unless they just go crazy with spark advance.
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