scoates

I picked up an 87 a few months back that someone had started to convert to a carb setup. I have it up and running but now I am trying to get the the tach working. The distributer is an HEI. I just have the hot wire running to it now. All the original wiring harness is still in place. I see the old plug for the TPI distributor. Which wire is the tach wire? Can I hook that straight to the tach side on the HEI? There was a wire that doesn't look to be original that is the same color as the tach wire in the HEI. It has some sort of filter looking thing on it and the plug that will fit the distributor but the other end of the wire has broke off. Do I need the filter(or whatever it is) or can I just tap into the original tach wire from the TPI distributor plug?

jfb

The tach output wire on the original distributor is a single white wire with a plug in connector on it that plugged into the left side of the distributor. My 87 electrical manual shows no tach filter. Contact your HEI distributor maker and ask them if you can connect the tach wire directly to their tach output terminal.

scoates

It is a stock GM HEI so it should work. I went ahead and put a jumper wire from the white wire on the plug and the tach side on the distributor. Nothing changed. The tach in the dash is lit up to max rpm. It stays this way with or without the jumper wire. Looks like I need to do some trouble shooting on the dash. Some of the other gauges do not work correctly either. Any tips on where to start?

REDC4CORVETTE

The plug is lose behind the dash.Upper right side,behind the odometer.That is if memory serves me well.

rodj

My '87 has a tach filter also.

Can only try , the filter is there for the dash , not the dist. If the readout is crazy , then you know you need the filter.