is there anything special that needs to be done to the computer or wiring, when a 302 motor is replaced with a 347 ? a guy at jegs said the computer would not work for a 347.
A guy at Jeg's? Well I don't think I would tend to believe him. If the 347 is a mild build, then the stock ECU will be fine. If the car is 88' or older (except California) then the ECU will not be happy with the extra displacement. If 89 or newer (include 88' California) then the ECU will be fine with a mild 347. If you are doing a serious build, you would want a custom chip to take advantage of it anyway, and a serious build would benefit from a stand alone engine management system. I suppose you could be a bit more specific so that the answers are not generalized, like this one.