Mattax said

So odds are that its already advancing. When the engine slows down (transmission placed in gear) timing decreases. How much depends on how quick the primary advance is. it can be pretty dramatic as illustrated above. If you have four hands and an extra foot you can see that in the timing light and tach. Just be careful if measuring timing in gear! The extra hands and a foot on the brake is better than relying on chocks alone.

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