Sorry for jumping in I have modeled the block in cad software and I am having a hard time to get both idler gears to mesh with the crank and cam gear .Do I need to adjust something to get both in? One will work fine but I cant seem to fit both ?Thank you sir .
I think that the confusion comes from the gear diameters specified is the OD of the , gear. The pitch diameter, where the teeth touch is different.
The OD of a gear is equal to (N+2) / DP and the Pitch diameter is equal to N X the DP, where N is the number of teeth and DP is the diametrical pitch.
Thus for the 48 tooth gear the OD is ((48+2) / 48) which is where the 1.0417 dimension comes from. But the Pitch diameter is equal to (48 /48) or 1.0000. Same thing applies to the 24 tooth gear which equals a Pitch diameter of 0.5000.
Thus the ratios of the pitch diameters is the 2:1 that you were expecting.