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The 4-cyl 2.2 L Camry engine has 24 teeth on the crankshaft wheel and 48 teeth on the camshaft. Each timing belt tooth indexes the crankshaft by 15 deg (15x24 = 360 deg), the camshaft by half as much or 7.5 deg.
Typically engine cycle events -- spark, valve opening and closing -- are given in terms of crankshaft angle. For example, when the spark is timed at 10-deg BTDC, this is with respect to the crankshaft.
What I reported above is considering how the shop installed the belt and how I changed it, I operated the engine with valve timing over a range of 2 belt teeth or 30 crankshaft degrees. I didn't even know that you could change it that much without preventing the engine from starting or even doing damage, but the Toyota has a "non-interference engine" where you won't hit anything, and maybe the ECM is able to compensate for this wide range.
The performance was off the way the shop had it, the performance was back and the gas mileage was great the way I set it, but the gas mileage wasn't really that good because the way I set it changed the Scan Gauge readout in relation to what went into the tank.
Has anyone experimented with the cam timing with respect to idle vacuum, engine compression, MPG? I am tempted to experiment, but it takes me 3 hours to get at the top timing belt cover, change the camshaft alignment, and put everything including the cover, engine mounts, and alternator belt back together.
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