Ignition help I think?

Rick Kagawa · 11-10-2023, 08:01 PM

My car is a C/SA 1970 Chevelle L78.
I am looking for some help with an issue that I can’t figure what else to do next.
It started in Spring of 2022. The car was running well. Then my MSD Digital 7 Programable 7530 stopped working. Since it is potted, it was unrepairable and trashed.
I replaced it with an MSD Grid. The first time I started it up, it was fine. I turned it off and then it wouldn’t start. I sent both the Grid and the ignition box back to MSD. After some time they shipped me both pieces back new. I then installed the new boxes.
After that it ran OK but it had a miss that made me crazy. I sent the boxes back in to MSD. They replace them again. I reinstalled the boxes.
The rotor, cap and spark plug wires were replaced. MSD personal were at the race and they completely looked at the system. They gave it their blessing.
I was still chasing inconsistent misses. I then took it to my local race shop. They found that the Grid box negative ground was never crimped from the factory. It pulled right out of the connector. We checked all the other parts of the ignition wiring. At that point, I thought my problems were over.
I went to a divisional race. The car was really slow. It would barely run the index. It was slow at the 60 foot by .1 to .2 slower than usual. The MPH was down by 7 MPH. This car usually runs .7 to .8 under the index. Overall it is slow and The RPM fluctuates in third gear.
I brought it back tp the speed shop. We put in a 16 volt system. I checked the compression. All cylinders were within 5 pounds of each other.
I thought that maybe the sprag had gone out. I replaced the torque converter. I went back to the local track. No appreciable change.
I got frustrated and replaced ignition system again with another new Grid and ignition box. I also replaced all the ignition wiring.
I then went to the next divisional hoping that the ignition would fix the problem. In the test and tune, no change.
I have sent the Racepak runs and the MSD Grid Review runs to MSD. They told me that they saw nothing unusual. I tried a run with the tachometer disconnected.
I have heard many times the gripes about the Grid. How much you hate them. Most people have no problems with them. I am not looking for your opinion about the Grid.
I am looking for places to investigate and try to fix my car.

11-10-2023, 08:01 PM	#1
Rick Kagawa Junior Member Join Date: Apr 2008 Posts: 32 Likes: 1 Liked 3 Times in 1 Post	Ignition help I think? My car is a C/SA 1970 Chevelle L78. I am looking for some help with an issue that I can’t figure what else to do next. It started in Spring of 2022. The car was running well. Then my MSD Digital 7 Programable 7530 stopped working. Since it is potted, it was unrepairable and trashed. I replaced it with an MSD Grid. The first time I started it up, it was fine. I turned it off and then it wouldn’t start. I sent both the Grid and the ignition box back to MSD. After some time they shipped me both pieces back new. I then installed the new boxes. After that it ran OK but it had a miss that made me crazy. I sent the boxes back in to MSD. They replace them again. I reinstalled the boxes. The rotor, cap and spark plug wires were replaced. MSD personal were at the race and they completely looked at the system. They gave it their blessing. I was still chasing inconsistent misses. I then took it to my local race shop. They found that the Grid box negative ground was never crimped from the factory. It pulled right out of the connector. We checked all the other parts of the ignition wiring. At that point, I thought my problems were over. I went to a divisional race. The car was really slow. It would barely run the index. It was slow at the 60 foot by .1 to .2 slower than usual. The MPH was down by 7 MPH. This car usually runs .7 to .8 under the index. Overall it is slow and The RPM fluctuates in third gear. I brought it back tp the speed shop. We put in a 16 volt system. I checked the compression. All cylinders were within 5 pounds of each other. I thought that maybe the sprag had gone out. I replaced the torque converter. I went back to the local track. No appreciable change. I got frustrated and replaced ignition system again with another new Grid and ignition box. I also replaced all the ignition wiring. I then went to the next divisional hoping that the ignition would fix the problem. In the test and tune, no change. I have sent the Racepak runs and the MSD Grid Review runs to MSD. They told me that they saw nothing unusual. I tried a run with the tachometer disconnected. I have heard many times the gripes about the Grid. How much you hate them. Most people have no problems with them. I am not looking for your opinion about the Grid. I am looking for places to investigate and try to fix my car. Last edited by Rick Kagawa; 11-10-2023 at 08:04 PM.