So I have a 1986 Iroc that I have completed a swap to a 350cid and 700r4 transmission. None of the gauges are working except the fuel and voltage. My mechanic is trying to say that my gauges are electric but everything I keep seeing says my gauges should be mechanical. So first question is are my gauges mechanical or electrical? Second question if they are indeed mechanical, any ideas why my gauges would not be working and what I can do to make them work?

 

In 86 the speedo is mechanically driven via a speedometer cable off a fitting near the tailshaft of the trans. If it's not hooked up, you will have no speedo. If it's hooked up but the speedo calibration gears in the trans aren't right for your application, the speedo will work but it won't read correctly.

All other gagues are plain old electrical gagues, and not routed through the ECM. Just old school electrical connections to various sensors under the hood.

Tach takes it's signal off the negative coil terminal (white wire that would hook up to the "TACH" connection on the side of your old large cap HEI distributor in a stock application). Basically, it needs to be attached to the negative terminal of the coil, unless you are using an ignition amplifier box (MSD), in which case it needs to be hooked to the Tach output on the box.

Temp gague is driven by the one-wire sensor that's screwed into the driver's side cylinder head between the #1 and #3 spark plugs.

Oil pressure gague is driven by the sender screwed into the block just above the oil fitler (3 wire sender, one of which supplies oil pressure readings to the gague. The other two wires are a backup power supply system for the factory in-tank fuel pump).

 

Are the sensors on the engine for idiot lights or gauges?

FWIW, mechanical gauges like oil pressure use tubing to allow fluid to flow to the gauge.

 

And 86 IROC would have been gagues.