Teach me about dwell meters

[38plymouth]

I want to set my points with a dwell meter. I don't own one so I started searching  for one and almost everything pops up as a regular multimeter. I have analog and digital multimeters already but I don't think they will really measure dwell. If they do how do I do it? If not what dwell meter should I buy? I can't find anything local except at harbor freight for $50. I'd rather not spend that much for a tool I might use 5 more times in my lifetime.

[DJK]

I have a Mac ET910 that I used back in the day(40 yrs ago) that will not read dwell on my 6v pos. ground Cranbrook. My former service manager gave me his Snap On PDM MT500, that works fine. I had previously purchased an Actron CP7677 from Amazon, will not read dwell. Check Ebay is your best bet or find an old technician that has one.

Edited October 10, 2021 by DJK
spelling

[Sniper]

I have two dwell meters, an old analog one I've had since probably the 80's and a digital one built into an automotive multimeter, it is definitely more than just a dwell meter.  No, a regular multimeter will not measure dwell.   

 

https://www.amazon.com/gp/product/B0002LZU7K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Edited October 10, 2021 by Sniper

[busycoupe]

I have an old '80s era Sears dwell/tach I found at a yard sale.  The instructions say that it works on 12v neg. ground, but it works fine on my 6v pos. ground 1948 Dodge.  You just need to be careful of the polarity when you hook it up.  These meters show up regularly on ebay for short money.

[keithb7]

Use my dwell meter a couple of times per year, per car. Tune up in the spring. Checking for something or other mid season.  It’s good tool to own in my experience. You can eliminate one possibility when troubleshooting symptoms. 
 

I own a Snap-on model MT-816B.  It reads RPM and dwell. 6V is no problem. As long as it is hooked up before I start the engine. If hooked up after engine is running RPM won’t read RPM for some reason. I suspect it’s a 6V related issue. 
 

 

Edited October 11, 2021 by keithb7

[capt den]

i have an old analog my grandfather bought me back around 1966. still works. made by a company in brooklyn, ny, and he got it mail order. it was around $25 then and you can get ones today for not much more. if you think $50 is too much for something these old cars need then keep looking on ebay,craigs list and other sites, including yard sales and swap meets. i am going to the moultrie GA swap meet next month and i would bet there will be a few there for sale. timing lights may be easier to get, i still have an old penske from about 30 years ago. it is 12 volt, but works on 6 volt too.    capt den

[keithb7]

In general expect to pay more for a quality built tool such as Mac or Snap-On. Craftsman/Sears brand will attract a lower sell price. Yet probably get the job done just fine. 
 

I had no problem spending $50 to $75 for a quality dwell tool too help keep my old cars running reliably. Doing all your own maintenance and repairs? You are already saving lots of money on hourly shop labor costs. You may want to spoil yourself a little and buy quality tools. To me, totally worth it. 

[RNR1957NYer]

2 hours ago, busycoupe said:

I have an old '80s era Sears dwell/tach I found at a yard sale.  The instructions say that it works on 12v neg. ground, but it works fine on my 6v pos. ground 1948 Dodge.  You just need to be careful of the polarity when you hook it up.  These meters show up regularly on ebay for short money.

I’ve got one of those I bought in the ‘70s but haven’t thought to try it on the P12.  When you say “be careful of the polarity”, how do you hook it up on the 6v pos ground system?  -  positive meter clip if connected to 12v per instructions connected to positive 6 v terminal?

[busycoupe]

Yes, the positive clip attaches to the positve batt. post, the neg clip to the distributer side of the coil.

[Art Bailey]

8 hours ago, DJK said:

I have a Mac ET910 that I used back in the day(40 yrs ago) that will not read dwell on my 6v pos. ground Cranbrook. My former service manager gave me his Snap On PDM MT500, that works fine. I had previously purchased an Actron CP7677 from Amazon, will not read dwell. Check Ebay is your best bet or find an old technician that has one.

I have the ET 910, and same, it wouldn't work on 6v pos. I dug up a 12v wallwart, clipped and stripped the end, and used it to power the tach. Worked great. 

[RNR1957NYer]

4 hours ago, busycoupe said:

Yes, the positive clip attaches to the positve batt. post, the neg clip to the distributer side of the coil.

Thanks for clarifying- that’s the exact same meter I’ve got!

[Bryan G]

Great information, folks. I have an 80s Sears that I picked up at the flea market for the price of a cheeseburger, but "12v only" so I didn't give it a try on my older cars. I'll have to give it a whirl. One neat thing: it was missing the owner's manual but it was still downloadable for free from Sears (or at least was 10 years ago.) 

[DJK]

21 hours ago, keithb7 said:

Use my dwell meter a couple of times per year, per car. Tune up in the spring. Checking for something or other mid season.  It’s good tool to own in my experience. You can eliminate one possibility when troubleshooting symptoms. 
 

I own a Snap-on model MT-816B.  It reads RPM and dwell. 6V is no problem. As long as it is hooked up before I start the engine. If hooked up after engine is running RPM won’t read RPM for some reason. I suspect it’s a 6V related issue. 
 

 

Good info Keith.