Snap-On Tach Dwell Meter

[Y-Blockhead]

I usually hang out at the Model A Forum on the Ford Barn but hopefully one of you can help me.

I was given a Snap-On Dwell Tach Model # MT-715 the other day. I was wondering if anyone knows where I can find instructions for it. I Googled it with no love.

Connecting it is pretty straight forward, I am just wondering about the knob on the far right, specifically the "Set" setting and the volt positions? It doesn't have any hard detents, more like a potentiometer. Thanks.

I'm told the dwell angle for a Model A distributor is 42°.

 

[crewchief888]

Snap on emailed me a manual for a mid 80s meter a few years ago. Might be worth a shot.

 

[Wrench97]

How many leads are there 2?

 

[Y-Blockhead]

Yes, two leads. It is self powered as it has 3 "C" cell batteries inside (which I just replaced).

 

[Wrench97]

Black to ground, red to the points side of the coil.

 

[Y-Blockhead]

Thank you Wrench97, that helps. What I am really confused about is the far right switch?? I understand the "SET" position, but do I then turn it to 12v (or6v, or 24v) when in a test position on the middle dial. The right stitch is like a potentiometer, no hard detents.

 

[Y-Blockhead]

crewchief888, thanks for the suggestion. I just e-mailed Snap-on. We'll see if I get a response.

 

[Y-Blockhead]

Response from Snap-on;

I do not show us carrying a manual for the MT715 any longer in our system.
Thank you for contacting Snap-on Tools.

 

[Y-Blockhead]

I just connected the meter to my '30 Model A Ford. Seems to work fine as it reads the same as my Sears Dwell Meter. The switch on the far right does not seem to do anything at all (except for when in the "SET" position). I turned it to all voltage settings while turning over the engine with no changes in the reading.

 

[Wrench97]

Turn the center knob to "Set", connect the 2 test leads together, use the right knob to make the needle swing into the "set" range on the meter.

 

[Y-Blockhead]

When I turn the center knob to "Set", the needle swings over into the "set" range. It does matter if I have the leads together or not. It seems to be working fine, I just don'r t understand the voltage settings.

Snap-on tells me the MT-715 meter is from 1967! Still working.

 

[Wrench97]

Does the needle move if you turn the "voltage" knob?
The voltage setting is a new one for me too, mine is from the early 70's and does not have it.

 

[Y-Blockhead]

No, the needle does not move. That is what has me confused. I just set it to 12v when I checked the meter but there is no change in the reading when i move to 24v.

 

[AL`]

Would think you just set it to the voltage for the system of the vehicle. So 12 V for most stuff, but some older vehicles were 6 V and some larger trucks and busses 24 V. Think military used or uses 24 volts too. Why the needle didn't move is a question though.

 

[Y-Blockhead]

Well it seems to work and it cleaned up nicely. And the price was right, FREE.

 

[Milton Shaw]

The first generation GM cars with computer controlled carbs, the signal with the jumper in, was a 30 degree dwell reading to give you something to check the calibration with. It was also a 30 degree dwell before it warmed up and went in closed loop as I remember. Good find although you won't find a lot of cars still to use it on.

 

[Wrench97]

Use the screw on the meter face to 0 the needle.

 

[Y-Blockhead]

Milton, that's true. Probably the only car I will use it on is my '30 Town Sedan..