i put a m42 into my 77 e21. the M42 swap is actually pretty popular with the 2002/E21 groups.
i'm running a 3.91 diff and get 27 mpg. with the M10, k-jet injection, and a 3.64 diff, the best i could get was 19 mpg.
this is the engine that the 2002/E21 was meant to have.
it was easier to put a level on the oil pan than to gauge a 60° angle. i guess you could also attach an angle gauge to the top of the head.
