The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - In-dash tach for a 6

*HEI451* · 10-14-2011, 10:47 AM

A note about the earlier Sun tach's, they require a sender to get them to work correctly, senders are engine cylinder number specific, so, if yo find an early Sun tach on places like E-Bay, be advised, they will need the correct sender to make them work.

That said, the sender uses two AA batteries inside it to power it, and the tach up. The original batteries were made as "Mallory", NOT the ignition company, but the special metal used inside them. Regular AA batteries will work in these senders, but the life span can be reduced with some AA types.

What I do with the sender power is to NOT use the AA batteries in them, but use a simple, inexpensive DC to DC voltage inverter, one that has the right voltage, and is sold by Radio Shack and other electronics stores. This way, the sender powers up when the ignition switch is turned on,,and the tach power is supplied by the vehicle battery, NOT batteries inside the unit. There would also be no dead batteries to stop the tach.

chevyrestoguy brings up a great point, there are those early Sun, and later Sun Super Tachs that have the 4-6-8- switch already in them, those would be the ones to try to obtain and use, as they do not need a separate sender, they just hook up with 4 wires, 12 volt power in, ground, signal from the coil negative terminal and light feed.

10-14-2011, 10:47 AM	#8
HEI451 Account Suspended Join Date: Mar 2011 Location: Yerington, Nevada Posts: 864	Re: In-dash tach for a 6 A note about the earlier Sun tach's, they require a sender to get them to work correctly, senders are engine cylinder number specific, so, if yo find an early Sun tach on places like E-Bay, be advised, they will need the correct sender to make them work. That said, the sender uses two AA batteries inside it to power it, and the tach up. The original batteries were made as "Mallory", NOT the ignition company, but the special metal used inside them. Regular AA batteries will work in these senders, but the life span can be reduced with some AA types. What I do with the sender power is to NOT use the AA batteries in them, but use a simple, inexpensive DC to DC voltage inverter, one that has the right voltage, and is sold by Radio Shack and other electronics stores. This way, the sender powers up when the ignition switch is turned on,,and the tach power is supplied by the vehicle battery, NOT batteries inside the unit. There would also be no dead batteries to stop the tach. chevyrestoguy brings up a great point, there are those early Sun, and later Sun Super Tachs that have the 4-6-8- switch already in them, those would be the ones to try to obtain and use, as they do not need a separate sender, they just hook up with 4 wires, 12 volt power in, ground, signal from the coil negative terminal and light feed.