Determining base timing
 

I am trying to time my engine that I believe is a bit of a "Frankenmotor." It is a 2.4 block with Euro 2.4 pistons, E cams, and it may have a Bosch distributor from another model. Every piece of literature that I could find regarding the base timing of a 2.4 E engine says that it should be set at 5 degrees ATDC. When setting it at this spec it becomes obvious that this is not right for this motor. It seems that between 12-15 degrees BTDC works best. As you can see there is a large discrepancy. Why?

5 deg. ATDC doesn't work for most engines, but that's the spec for emissions reduction for vehicles in the 70s and 80s.

Most engines run better with the timing slightly advanced at idle. However before setting the base timing to 12 or 15 deg., confirm the total advance (base + dist. adv.) doesn't exceed 30, 35 max. deg. BTDC. The distributor centrifugal advance weight mechanism adds to the base timing.

An advance-tracking timing light makes this easier and more accurate than observing the timing mark on the crank pulley, but it's doable.

Sherwood