318 BASE TIMING

Find a service manual for that 5.2
Consider that the baseline initial and timing curve.
Then measure what is on the engine.
make one adjustment at a time from there.
For a factory engine, the factory timing is going to be darn close.
When the combustion chamber, compression, valve events (camshaft) are altered, those are things that effect timing.
It's all about development of the flame front and the time it takes.
The goal is maximum leverage on the crank.

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