lets revisit timing
10* BTDC was the initial at 600 or 650 rpm for the 273 Commando engines.
That's a good example because the idle were altered for cleaner emmissions.
Techs could increase the initial or reduce it depending on altitude and fuel available if the owner wanted.
Notice the timing advances at least up to 3600 rpm.
Ignoring the retarded initial for emissions, we see the same thing on the timing specs for a '68 340.
Too much advance advance between 1500 and 3000 rpm might not be very noticible drag racing, but for other uses, it might be.
Uses such as lugging up a long steep hill, pulling a trailer, or pulling a boat out of the water. In those situations the loads can be high even in the lower rpms. So the factory made sure those possibilities were all covered. Then they figured how much additional timing would be needed for light to moderate load situations were the afr was leaner and the burns take more time to develop.
10* BTDC was the initial at 600 or 650 rpm for the 273 Commando engines.
That's a good example because the idle were altered for cleaner emmissions.
Techs could increase the initial or reduce it depending on altitude and fuel available if the owner wanted.
Notice the timing advances at least up to 3600 rpm.
Ignoring the retarded initial for emissions, we see the same thing on the timing specs for a '68 340.
Too much advance advance between 1500 and 3000 rpm might not be very noticible drag racing, but for other uses, it might be.
Uses such as lugging up a long steep hill, pulling a trailer, or pulling a boat out of the water. In those situations the loads can be high even in the lower rpms. So the factory made sure those possibilities were all covered. Then they figured how much additional timing would be needed for light to moderate load situations were the afr was leaner and the burns take more time to develop.
