difference between motors

[91318isfoundation]

whats the main difference between the 91 m42 and a 93 m42? becuaz i cracked the head on my 91 so ima just buy a used motor and i got another ecu with a chip for my 91 m42 will that chip work with the 93 m42?

[E30nate]

there are only minor differences in the valvetrain. smaller valve stems is the only difference i think. and the intake manifold. use your old manifold and it all works perfect. my 91 has an engine from a 95 in it right now and it runs perfect.