Coil Tester needed

v8nut

v8nut

Senior Member
Does anybody have a US source for a coil tester like the one shown. This one is a little pricy on ebay at $50 and I would pay that except it is in Columbia and would be 3 or 4 weeks to get to me. I would like one much sooner than that. Any help would be appreciated. Jim in San Jose.
 

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What I am looking for is a device that makes and breaks the primary circuit continuously so I can see the spark. I have a tester that measures the primary and secondary winding continuity and resistance. The picture posted is not very clear but there is a blithering continuous blue spark shown. That is what I want to do and see. Thanks for your help, Jim in San Jose.
 
Bob C said:
I got one like this on Epay.
Click to expand...

Sorry to hijack this thread- I have the older version of this Snap-on tester, (the MT-640), but it was missing the adjustment screw/knob when I bought it. I did make a replacement screw/knob for mine but I do not know what the "gap" between the brass points is when the indicator edge of the knob reaches the "green- good" margin is. Bob, if you get a chance, would you please measure this "gap" for me? This gap measurement may help others also with that product listed above on ebay.


Thank you in advance,
Kyle
Holt, MI
 
From the bottom of the knob to the tip of the point is 1 51/64".
I would like to find the neon bulb. It shows in the picture but the seller
did a lousy packing job and it was broken when it arrived.



Bob
 
Thanks Katy. That is exactly what info I needed. I will try to build the tester you show. Jim in San Jose
 
Bob C said:
From the bottom of the knob to the tip of the point is 1 51/64".
I would like to find the neon bulb. It shows in the picture but the seller
did a lousy packing job and it was broken when it arrived.



Bob
Click to expand...



Bob, thank you for taking the time to measure that. My Snap-On MT-640 model's stationary point appears to be about 3 times longer than the Snap-On MT-335 model. The adjustment knobs are different lengths. From your photo I think the two brass posts are about the same distance apart. Do you or any other members know what is a satisfactory distance the spark should jump for a 6 volt coil to be considered good.


Thank you again,
Kyle
 
Kyle, if you can borrow one of the cheap spark testers you could measure the spark gap at various voltages. May not be accurate, but should be close.
 

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I just read an article that showed a coil can be tested with an ohm meter by checking across the two small posts and then checking from one small post to the spark plug connector.

This was for the Model A but did not give any spec's as it said "Determine the resistance using your multimeter and check to see if it's within the acceptable range".

What is the acceptable range on a 6V coil on the Model A?
 
fordified said:
Bob, thank you for taking the time to measure that. My Snap-On MT-640 model's stationary point appears to be about 3 times longer than the Snap-On MT-335 model. The adjustment knobs are different lengths. From your photo I think the two brass posts are about the same distance apart. Do you or any other members know what is a satisfactory distance the spark should jump for a 6 volt coil to be considered good.


Thank you again,
Kyle
Click to expand...


Kyle, I measured the gab when the knob is in the green area and it
is between 9/32" and 21/32".


Bob
 
Bob C said:
Kyle, I measured the gab when the knob is in the green area and it
is between 9/32" and 21/32".


Bob
Click to expand...





Awesome!! Now I can fine tune the adjustment knob and test a few coils to see which ones are the best.
Thank you for taking the time to measure that gap. I'm sure it was not easy.
Kyle
 
The units which need a bulb use a Geisler tube. They were used in distributor testers and also the ball point looking testers to test for spark. Snap On used to carry them in their parts books. Don't know who presently supplies them. I can supply instruction sheet and schematic for the various Snap on testers.
 
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