Technical Moon tach no rpm reading

Hi guys, I just got around to installing a mooneyes tach that I purchased a while back for my 57 Chevy. red wire to ign. + black wire to good body ground, white to light switch, and the green wire to the neg terminal on my ign. coil. I am not getting a rpm reading on the tach. Has anyone else had this problem? Any info is appreciated!

 

blk might be a hot wire -do you wire houses?

 

Is it the one that look’s like an Auto Meter/Gauge unit?

 

Try swapping the green and white wires. White is typically the tach signal wire to Coil -.

 

This is the one I have

 

The white is for the lights, that part does work

 

Sounds like you got it wired correctly. The thing to do is eliminate the simple stuff (good ground, etc) which is sounds like you have. Only other thing I can think of is if there are any dip switches on the tach, that they're set correctly for the engine's cylinders (4v6v8, etc). I can't remember if that tach had that option or not. Shouldn't need a tach signal filter if it's a standard coil.

 

That's the conventional wiring scheme. Is the tach new or used? Has it run for you before?

 

I did not see any switch on the gauge I will take a better look at that. Thanks for your help

 

I purchased it awhile back on eBay it was new but not in box. This is the first time I hooked it up and it didn’t appear to be used before

 

Well, I had a Moon tach that looked just about like that on my dirt modified, and it worked great. You have it hooked up right, so it looks like somebody pawned a defective unit off on you.

 

That’s what I’m beginning to think also

 

One thing to check and I've seen this more than once, double check to make sure you have the right side of the coil.

Also what style of ignition are you running?

..

 

I am running an hei with a canister coil. I hooked the green wire up to the - terminal on the coil. I believe I got a defective tach

 

^^^^^ Try it on a points car.

 

Try hooking up the green wire to the tach terminal on the HEI distributor.

 

Seems like mine had a switch on the back for 4,6, or 8 cylinder. Don’t know if that would make a difference at all with the tach not responding if it is incorrect…

 

Hey guys, I took the tach apart and found the needle was stuck to the back of the gauge. Freed the needle and the tach now works.

 

May have been why it was for sale

Good job!

 

I bought one brand new with in a very short tine it quit, Moon warrantied it. The replacement quit before the end of the same summer.

 

Well thats annoying. ive been planning on buying that Moon tach for a '58 Edsel i'm working on and thought it would have have looked right at home in that car, but i dont want to dick around with it dying and having issues, regardless if they warranty it or not.