I put a 1977 motor in a 1978 280z

[geosecor]

I recently dropped a good running 1977 280z motor and trans. package into my 1978 280z and now have all 6 sparkplugs carbon fouling as soon as motor warms up. I have noticed the AFM has 2 less wires in connector on my '78. My '78 does not have the 2 green wires that go to fuel pump relay. I wired my fuel pump to igniton, so it is hot when key is on. What other differences are there between the '77 and '78 models fuel injection wise that would make the '77 motor run like crap, I have tried swapping computers, AFM's, throttle switches, and distributors to no avail.....also unplugged thermotine sw. air regulator, and water temp sw. and still have a ton of carbon coming out exhaust... geosecor

[slobound76]

Hard to say, I have a 77 280z and when I got it, it ran like you describe, but I just gave it a general tune job, changed plugs, all filters, wires, etc, just the usual, and it now runs like a champ, have no 78 experience, just know what mine did when 1st got it. Wondering, when you say carbon fouling, how many miles were on the 77 engine, if the plugs are carboning up, are the piston rings letting oil by up into the chamber?

[geosecor]

I dont think there is oil fouling going on here, just too much fuel or not enuf air I'd say. Will change out the thermotine sw. and water temp switch tomorrow, over 100K miles on replacement motor for sure, but alot of life left I believe. geosecor

[slobound76]

Okay, my 77's got 98k on it, and yeah, the switch could be a problem, mine's sure got lots of life in it, just keep in mind that with a 30 yr old motor, the rings have seen better days and probably were never changed...one thing to think about, am having my engine overhauled once becomes affordable Until then, the tune job i gave my baby still has her giving the local punks a good run for their money (expecially with a few mods and a centerforce clutch) and turns pleanty of heads

[geosecor]

Well, regardless of tuneups and ring jobs, I'd still like to know the exact differences between a '77 & '78 under the hood other than the fuel relay being moved in the 1978 model.

[geosecor]

yikes!!!! Just figured out car I got donor motor from has 91K miles, gotta assume that is 192K miles, guess it is time for a rings-job- good thing I got a running donor for less than $200.00!!!! got a nice 5 speed and good clutch out of it anyway. oh well- also found a bad air temp sensor which is making AFM sluggish to react to throttle response. thanks