Help with MFI
 

I have a '74 Euro Carrera with the type 83 (RS) engine. Recently brought it back from Denver, CO to Illinois.

My problem/question is does the MFI need to be adjusted to the lower altitude? Very rough start up and significant delay on acceleration. Usually have to play with the throttle to bring the power on. Also quite a bit of backfiring even when fully warmed.

If it is an MFI adjustment do I go richer or leaner and how do you tell when it is correct?

MFI has a barometric sensor built in that leans at high altitudes and richens the mixture at lower altitudes. That said, they don't always work correctly due to age. The best way I've found to tune MFI is to take it to a load dyno with an exhaust analyzer and adjust the MFI rack there.