I bought a 140 mph cluster from an 84 z28 it has everything in it.
The car that I want to install it in only has an 85 mph and the BIG fuel gauge with no other gauges, just warning lights.
Do I have to change any of my wiring around to use this cluster, or can I just go ahead and install it without having to worry about a dash fire?

 

You can just drop the new cluster in with the existing wiring, but you'll need to replace the oil pressure switch and coolant temperature switch for the gauge senders.

 

Thanks for the info, I'll post in a few days with the outcome.:hail:

 

By the way, I thought the 140 mph speedometer wasn't available in 1984.

 

Maybe somebody installed it in there, I have no idea.
But will it still work, or what years are compatible with mine?

 

It will still work fine. The original 1984 speedometer should be 85 mph with a double needle reading mph from the bottom left in white and km/h from the top right in orange.

 

yeh, is the new speedo cable driven? If so, that'd be an oddity....also, could the speedo have been a cable driven one, which someone ordered a overlay for giving it the appearance of 140 mph? If it's an electric speedo, then you'll be doing some re-wiring ontop of the sensor change. But yes, the senders must be changed to convert from basically an on/off switch (idiot light) to a full functional guage.