Here's is an interesting video:
I say, the Snap-on MT2500 is the way to go over the OTC (way more intuitive). It's the iPhone of vintage scanners. Newer S/O scanners are backward compatible to 1981 (usually), so if your mechanic has a S/O scanner it should work (he may need to source the 'right' cable and connector to read vintage vehicles). But the older MT2500 is inexpensive. A guy should be able to buy one in Oz fairly cheap too. There's tons of s/o scanner videos.

One of the issues that sometimes affected early GM ECMs were poor pin connections (the connector) at the ECM itself. In some cases the pins didn't fit properly and/or didn't make proper contact. It's resolved by slightly bending any pins back so they make contact on the ECM. There were a number of dealer Technical Service Bulletins GM sent out to the service departments in the early 80's. That's not something you'll find in any manual. So have your mechanic **CAREFULLY** check the pins at the ECM itself. Remember about 95% of ECMs people claimed were 'bad' back in the day, turned out to be not faulty (according to GM). Also, check all the connectors in general. Of all the GM CCC cars I ever had, pin connections were never a problem. But check yours.

A number of manufacturers besides just GM went through 'teething' problems with connectors back in the early ECM days, which they quickly sorted out. Nowadays bad connections are pretty rare. Cars have come a long ways, huh?!

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I checked the troubleshooting manual:
Stall on start-up or cold is usually EGR Hose mis-routed, or EGR issue. Emission hose routing should be on the emission sticker (hood). Let us know if you don't find one. Hose may be brittle and cracked. Check that, and EGR operation, or that it isn't heavily carboned-up inside and/or below the EGR (fairly common). There's a specific way to check EGR operation. Don't let your mechanic talk you into removing the EGR ..replace it (with the 'right' one). There's a part number on the top of the EGR. Ask your mechanic to check EVERY vacuum hose. By now they might be old and brittle and some cracked.


The secondary item to check is the carb. You could try unhooking the Mixture-Control Solenoid too and starting. But check the EGR first.

 

thank you i will tell the tech guy about possible pin bad contacts when i leave the car with them tommorow.

 

as i said the 350 runs well with the plug disconnected it starts runs clean and does rev out but as soon as you connect the plug that comes out of the bottom of the Delco Dizzy(4wires)it kills the motor. it is of to the mechanics tommorow we will see what they find.

 

Direct your mechanic to these sheets below, from the 1981 Corvette manual.

You might ask him to reconnect the dist and pull any stored codes, if there are any. The 5-pin OBD1 connector is under the ashtray. Put a wide spade connector between terminals D+E (the two furthestmost Left connectors) on the OBD-1 connector below the ashtray. Turn the ignition key on 'run' (don't start vehicle). Watch and count the blinks. Normally it will blink once ..then twice (=12), then repeat 2x more times. Code 12 is the reference signal from the distributor ..which it doesn't see when the engine is off. After the 3rd time of blinking '12' if there are any stored codes, it will blink those numbers out. Count the 'blinks'. For example, 2-blinks followed by 3-blinks equals code 23.

If he has a snap-on scanner (especially an old one) with 'Domestic US' software that goes back to 1981 (and the right connector & cable), he should be able to read data too. But the entire system can be troubleshot with only basic voltage checks and tools he should have in his tool chest.

Follow the troubleshooting tree below.

 

Thank you for the effort you put into your reply to my dramas i have printed out your pages and will pass them over to my mechanic Friday he is keen and a good tradesman but he was a baby when my corvette was new we seem to be loosing a great deal of knowledge as time marches on . thanks again PAUL

 

Ok, I found (in a different book) more charts in the CCC Diagnostic's GM Book 212. Start with the first two below:

 

thank you for the pages i will pass them on to the mechanic ,I found it relevent when one of your pages sent goes down the parth of motor running with dizzy not connected to ecm thanks.it should be very helpfull, PAUL