How do you hook up an external tach. Where on the distributor does the one of the wires hook up? It is a portable hand held tach thingy. I want to set my IAC but car doesn't have tach.

 

I don't remember ff hand how the 6A was hooked up, but either a) try a search

&/or

b) check out MSD's web site on hook up diagrams, they list the tach wire in those I belive.

 

Coulda just done a search, I've posted this many times.

You want the black/white wire, from the gray coil connector.

For more info, see here: https://www.thirdgen.org/techbb2/sho...hreadid=193133

 

I don't want to mount it permanently. I just want to be able to attach it under the hood while I work on the car. It's one of those "EL cheapo" hand held tach/dwell tester units. So splicing is not a real good option. I have a regular gm hei unit on my truck that I can just plug one the the tach wires into. It clips in and out nice and easy. Does the firebird have this ability?

 

Ah; gotchya. "Supposedly" the later model 2.8 and 3.1's had an extra wire piggybagged onto the black/white wire I mentioned. The wire ended in an insulated terminal and was tucked along the wire loom; that's where the diagnostic tach would go.

Even my '86 GM book shows that wire; but my '86 2.8 doesn't have it... and I've never seen it on any junkyard car, either. So you could splice a short 2 inch length wire into the black/white wire, add a terminal to it, and cover it up good. Check along your ignition coil's wiring loom; maybe you'll get lucky and it'll be hiding there.

 

OR.......you could kill 2 birds w/ 1 stone and buy a timing light that has a digital tach readout.

LOL, I just look for excuses to buy new tools......