GM DIS for the Chevrolet Corvair
This is a wasted spark system from any GM 2.8/3.1 and available at low cost. Project is complete and only cosmetic work is needed.
Goals for the project are the same as the fuel injection project.
This will be controlled by a GM 1227747 ECM already Installed in the Corvair running the GM Dual TBI fuel injection.
I used the Saw blade as a guide to figure out where the slots need to be placed. I used the existing HEI to run the engine and had the GM DIS setup on the inner fender and with a timing light, I marked the proposed location of the holes in the harmonic balancer.
The harmonic balancer has holes drilled in 2cm to make the sensor fire the coil pack. The Corvair is a reverse engine rotation so it moves counter-clockwise. The Pulse and sync pulse were drilled at 80 and 90 degrees which gives the Corvair a 10 degree BTDC with the Tan wire disconnected. The Sensor is located at 90 degrees BTDC. Timing offset is critical as the engine will start with the ECM disconnected, but will not run connected. If the ECM programming is set as a GM HEI, then it would be trying to start at -60 degrees timing.
3 Jan 09: It works.... and it works well, First road test today. The timing is dead nuts steady and I can feel a difference in the engine. It is slower cranking than the GM HEI (Takes 1 whole spin before it knows where #1 is) so I increased the Startup Timing 10 degrees and appears to be starting better. The Sensor holder has been re-engineered and works great now. The sensor distance is gauged using a credit card, but will work with 2. Watching the engine run even while accelerating with a timing light, there is 0 timing scatter.
Now its time to make the wiring look pretty and make sure the I have not missed anything. I feel good about this project, but I'm keeping everything I need to convert to GM HEI in the trunk for at least a couple thousand miles.
10 Jan 09: I replaced the Belt with one of those thick ones from Clarks (Gates Belt) and its rubbing against the sensor. I cut a groove in the sensor and will be watching the results and I'm going to X-ray a sensor so I can see how far I can cut back. Also still working the computer for the newest bin file (romulator) and it only gets better and better. I love this car!!!
Update 13 Jun 09: Turned over 100,000 Miles and back to zero. The injection system has a good 25,000 miles and the DIS has about 8500 miles and all with no failures (yet... knocking on wood). I do miss having something to do with my car though.... maybe I will wash it.
A Big Thanks to Bill Hamilton which help me figure the offset and support on the 7747 ECM and Ed Powell's auto salvage which supplied all the parts for this project at a very reasonable price.