Cars run better with better ignition
My friend gave me some LEDs of the correct colors for my birthday, so I decided to finally get a better tach since I was going to have the instrument panel apart anyway.
The original tach was an Auto Gauge that didn’t match my Auto Meter speedometer. The Auto Gauge tach, I thought, was starting to wear out or burn out, because it started fluttering at high RPMs. As it turns out, it wasn’t defective at all. So I ordered a matching Auto Meter tach from Jegs.
I put the new LEDs and the new tach in. I had to increase the holes a bit, but I didn’t mind. The dial on the tach is much larger and the LEDs were pretty. Connecting the tiny wires was tedious.
I finally finished installing everything and I tested it. That was a disaster. The LEDs burned out, and he dash fuse blew. It would have been nice if that could have happened the other way around. It turns out that the LEDs were not 12-volt even though they were sold as automotive parts. They were 5 volt, and I was supposed to use some kind of a converter.I decided to go back to the old LEDs and be done with it. So I put them back in and tested it. The fuse held, but the LEDs no longer work. Worse, the tach also didn’t work.
I gave up on the LEDs and worked on the tach. I tried everything I could think of to get it to work. I tried a new signal wire from the coil negative terminal. That didn’t work. I tried a new ground wire directly to the battery; that didn’t work. Actually, the tach did work when I pulled the ground wire. This does not make sense. All I can figure is that the tach signal was getting into the key-on power wire.
I called MSD first because the ignition is an MSD Ready to Run distributor with an MSD Blaster II coil. MSD said it should work and suggested I call Auto Meter. MSD does make a tach adapter, but it should not be necessary for the equipment I have. In fact, I should have needed it for the old Auto Gauge tach.
I called Jegs next, because I was worried about the Auto Meter warranty. Jegs said it doesn’t make sense, it should work, and I should call Auto Meter.
Auto Meter said it should work. The Auto Meter tach is designed to handle the equipment I have, and not to worry, I haven’t done anything to void the warranty. Auto Meter also said that the tach would never work without the ground wire (maybe he thought I was hallucinating).
This tells me I have a strange electrical problem. I thought about it for a few days, and I could not come up with a reason why this tach is not working. I thought about buying the MSD tach adapter anyway, but it didn’t make sense. The whole time, in the back of my mind, I thought about the MSD spark amplifiers that have tach outputs. Why would I blow money on a tach adapter, when I could upgrade the whole system and avoid the problem altogether.
I decided to get the MSD 6A ignition. I didn’t spend the money on the rev limiter model because the 351 runs out of power at about 5500 RPMs anyway. I installed the 6a. Everything went well. I ran a new signal wire, a new key power wire, and a new ground wire to the tach. I was happy to note that this setup isolates the coil from the rest of the electrical system. I tested it, and it works. Not only does the tach work (and it is beautiful), the engine runs much better. It no longer hesitates when the secondarys open, and it runs strong up to 6000 RPMs (note: The engine is balanced, it has forged rods and pistons, roller cam, roller rockers, and heavy valve springs. OEM 351W engines normally redline at below 5000 RPMs).
Two lessons learned:
Don’t go cheap on ignitions. The MSD Ready to Run distributor worked great for years, but it had limitations.
When upgrading to a new ignition, don’t think about how the engine runs with the old one. I should have gone with the rev limiter.
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