I have a 92 camaro RS. I just swapped a rebuilt 350 out of an 86 vette. It was converted to carb and I have had no problems for a few weeks. Yesterday I decided to put a new tach in because the stock one was way off. In the middle of running the wires i had to go somewhere and it ran fine. I got back and finished the job. Now when I start it it will run for about a minute and then dies. If i wait about 5 min it will do the same thing again. The only wire I cut was the wire that ran to the old tach from the distributor and connected it to the new one. The tach works great. I checked that all the wires are connected and I cannot figure this out. I need help and I'll try anything.

 

Probably something to do with the new tach. Have you tried disconnecting the tach to see if it will run better? That would be the first thing I would do. The new tach, is it a direct replacement or an after market part? Are you using the ECU to control timing or are you running a vacuum advance type distributor with the carb setup? When the engine dies, do you have spark? If not, why? Is the ICM (original distributor) signaling the coil to fire? Could be a short on the tach side of the coil causing it to not fire. Check your wiring for any bad connections or chaffed spots that could cause a short circuit. HTH!

 

Its an aftermarket bosh tach. I tried disconnecting the power and ground to it and it still did the same thing. Its running a vacuum advance and has a new HEI distributor. When it dies the rpms slowly decrease and it starts to sputter and eventually dies. Trying to give it gas to keep it going makes it die. Im not sure about it having spark and there are no bad connections i can see.

 

Disconnect the tach lead from the distributor and see if it makes a difference. Power and ground to the tach have no effect on the signal side of the tach/coil. Sounds as if your tach is killing the signal from the ignition control module in the distributor. If disconnecting the tach lead makes a difference, I would try a different tach and see what effects it would have. Maybe hook up the original again and see if it does the same thing. If the same problem, I would replace the ignition control module in the distributor with a good quality piece.

 

I hooked up the old one and it still happened. Then I unhooked everything but no luck. I'm going to replace the ignition module. Maybe it went out by coincidence