I haven't even taken a good look yet so I guess I'm just looking for some ideas. I've noticed that when Rolling along at speed the tach reads different rpm's for the same speed. It's inaccurate most of the time. I can be doing 65 mph and at different times it will show 22, 26 or 32 rpm's for the same speed. It's also very unresponsive to throttle blips and appears to be trailing real rpm's. A Mallory electronic fires off the plugs. I've thought of a tach filter though one knowledgeable friend said don't count on that fixing the problem. I'm kind of looking for your thoughts and direction before I go out and heat up the garage...Thanks, Frank

Frank, is the tach an old one resurrected or a newer one? If a newer one did you check to see if it is set for an 8 not a 4 or a 6. Never had the problem myself except for one that went south.

It's pretty new Jack. Can't be more then a couple of years old. It's part of a new 6 pack..Frank

but did you check to see if it's set right?

I must have the same tach. It just seems to wander at times but not all the time. I figured I would run another wire and use a grounded,shielded wire and ground one end. That should fix it but I haven't messed with mine so far. I would ask S-W what you should do, I'm sure they can tell you how to fix it....Ray
Let me/us know what S=W has to say about this please...
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Grump

Are you guys driving tupperware bodys? Could be radio interferance. Vettes had to sheild the plug wiring for that reason. Just a thought. Dave
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Life's too short to drive an ughly car!

I shouldn't have to answer this but mine is iron...
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Grump

Frank, Make sure you have a good ground wire going to the ground terminal on the back of the tach. Dont rely on the tach grounding through the mounting hardware. Had the same problem with a brand new one and the ground wire fixed it.
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KEEP THE GREAZY SIDE DOWN! Lobucrod

Thanks lobucrod & Ray, I'll be sure to try an alternate (good for sure) ground and let you know if that solves the problem. Yes Dave, it's a "tupperware" car, which would lead to check the ground, I suspect. Thanks, really. No Jack I haven't checked the setting but will report when I do. Ray, with regards to contacting SW. I've tried twice via e-mail and get nothing, nada, zilch in return. I was going to stop at the local dist and pick up a catalog which they say has the wiring directions for all their gauges. Kind of a double check. I'm sure we'll chat. If and when I contact them I'll report back with what they say. Thanks again guys. Happy Holidays, Frank

Thought I might be able to add some useful information. This only applys to older tachs that use a sender box. A sender box such as used on Sun & S/W vintage tachs were specific for 6 or 12 volt and for the number of cylinders... They also had a battery inside...the battery goes bad. But, even when the battery and all else was seamingly ok, the readings would drift. So, cars with serious requirements for accurate tach readings used cable drive. Later tach manfacturers went to circuit boards inside the tach head, and therefor no need of a battery to stabilize the reading.
I ran across a man in Michigan who can build a circuit board for any tach...he can put it inside the tach head, or inside a emptied out vintage sender box, and run the wires to the vintage tach for 'original look', and probably other options. But he's not cheap. His prices start near $ 200 & go up. It is:
Bob's Speedometer
32411 Grand River
Farmington, MI 48336
1 800 592 9673
Also Stewart-Warner dosen't exist today except in name only, they have been bought out about four times in the last few years and the current owner is not interested in returning e- mails. But there is one remaining man from the original S/W who is able to help. His First name is Craven at 1 704 758 8506.
If you must try the corporate owner, try 1 800 676 1837...#1 for customer service...Hope this helps...of course, maybe it was more than you want to know.

That's good info George. Mine is a newer model yet it's good to know the rebuild/upgrade stuff for swap meet pieces. Interesting about SW. That explaines their lack of response..Frank