Dolomite Posted February 14, 2015 Report Share Posted February 14, 2015 I changed my plugs and wires today and afterward my stock tach doesn't work anymore. I put in ngk plugs and wires, switching from ratty old autolite stuff. All connections are intact and none were messed with. It worked right before the change and never worked after. Any ideas? Quote Link to comment
datzenmike Posted February 14, 2015 Report Share Posted February 14, 2015 This is a white needle tach? Quote Link to comment
Dolomite Posted February 14, 2015 Author Report Share Posted February 14, 2015 Orange needle Quote Link to comment
datzenmike Posted February 14, 2015 Report Share Posted February 14, 2015 That's the early one and is connected in series with the points and the coil negative terminal. If the wire was broken or a loose connection... the engine wouldn't start. Strange, it wouldn't quit from changing plugs and wires, but.... Check the coil again. The only thing that could have got close to the tach was replacing the high tension lead on the coil. Maybe a wire on the coil was disturbed. Quote Link to comment
Dolomite Posted February 14, 2015 Author Report Share Posted February 14, 2015 Everything is tight and connected correctly. It's a definite head scratcher. Is there any chance it could be the plugs? The new ones are ngk resistor type, but that's what's listed as the correct plug on the ngk website and in Napa's computer. Quote Link to comment
datzenmike Posted February 14, 2015 Report Share Posted February 14, 2015 Plugs are fine and are on the secondary side of the coil. The tach get's it's signal from the primary side that the points are on. Quote Link to comment
Dolomite Posted February 14, 2015 Author Report Share Posted February 14, 2015 Shit, forgot to mention its an l20b with remote igniter dizzy using GM ignition module and Accel coil...brain fart. Still, it worked when I turned off the ignition to change wires and didn't work after. I guess it could be odd luck and just broke but I just don't believe that. Quote Link to comment
Doctor510 Posted February 14, 2015 Report Share Posted February 14, 2015 The pick up coil in the dist could be bad. Quote Link to comment
datzenmike Posted February 14, 2015 Report Share Posted February 14, 2015 Shit, forgot to mention its an l20b with remote igniter dizzy using GM ignition module and Accel coil...brain fart. Still, it worked when I turned off the ignition to change wires and didn't work after. I guess it could be odd luck and just broke but I just don't believe that. Your tach senses the.... on, off, on, off, pulses of the coil being grounded through the - (negative) coil terminal and the C on the HEI module. All the module does is switch the coil to ground and off again to cause a spark (but you probably know this) Some where the tach is connected to the coil negative terminal. Can't help more than this as it has been wired differently than stock. Just check everything. 1 Quote Link to comment
Dolomite Posted February 14, 2015 Author Report Share Posted February 14, 2015 So it seems there was a short between the stock tach wires. The car would run but no tach. So I rewired it independently and its good to go. Thanks for tossing me ideas guys. Quote Link to comment
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