My 30+ year old dwell/tach meter died .... I need a replacement.

Found lots of units on ebay ... $10 to $120

Found two Sears units that looked interesting as they had an inductive pickup.

Problem .... they say 4,6 or 8 cylinder but no switch!

My best guess is that these units somehow "count" the coil pulses and the #1 pulse and figure out 4, 6 or 8 .... but is this correct???????

I didn't think a dumb meter (20 years old) would do this.

I just want to make sure even if only spending $25 -$50 (usually $15 shipping) it will work on my 6 cylinder.

Is there any other unit anyone would recommend?

... also need a recommendation on a timing light, mine only works some of the time .....

I have a GM HEI style ignition on my 300 Ford ( tach connection on cap ).

Below is a link to a manual for one of the units I found on line.

Thanks so much ...... Mike

https://www.manualslib.com/manual/49...61-210400.html

 

inductive pickup for a tach/dwell meter?
Maybe for tach but I cant see how for dwell.
Do you have links to the meters you are looking at?


For timing light I would go inductive pickup and also get a dial back so you can check advance of the dist.


My light is a Snap On inductive pickup dial back I have had forever.
My tach/dwell/volt/amp meter I have had longer than forever. Don't know who made it but it is a good one I got when in high school, late 70's.
Dave ----

 

I like the cheaper light
https://www.summitracing.com/search/...iming%20Lights


Tach/Dwell/Volt meter
https://www.summitracing.com/search/...Dwell%20Meters


I did not look at reviews for any of them but for under $100 I don't think you could go wrong.
Dave ----

 

Wow .... I actually looked and didn't see any "old school" meters.

Here is a link to one of the units I was looking at ... this one is $49 but I saw them all the way down to $10.

http://www.ebay.com/itm/Sears-Solid-State-Electronic-2821040-Engine-Analyzer-Original-Manual-Box-/272459898652?_trksid=p2141725.m3641.l6368
Here is a link to the manual:

https://www.manualslib.com/manual/49...61-210400.html

I just don't understand the inductive pickup unless they are using it for the tach ... but again then how the 4, 6 or 8 without a switch????

Thanks ..... Mike

 

Look closely at the scale. Most inexpensive meters will have more than set of marks. One set is usually for 6. The second set is for 4 and 8. You're supposed to take the 4 cyl reading and double it for 8 (or was it visa versa?) This style is real annoying to use, so look for the type with a switch.

 

I thought this at first also .... but looking at the unit, only a single scale.

Thanks .... Mike

 

Its the other way around.
I cheated in his post with the link to the ebay ad it shows a picture of the scale.


I don't know if I would go for something like that where it is old but not used? It could last 50 years or 50 min. If 50 min you are then out $50 if you buy new if it does not workout of box most of the time send it back. Warranty is about a year on most things like this so good for a year if it stops working.
Dave ----

 

I see dwell scale for 4, 6 & 8 cylinders.
Rpm's are twice the spark rate no matter what number of cylinders you have. (There is a low and high range)


I was setting points timing on my buddies RD with a dial indicator the other night.
Never again...
(yeah, right!)

 

Mike, I just had an a-ha moment, followed by slapping my forehead. You mentioned needing a dwell meter so I automatically starting thinking about setting points. Obviously you won't be adjusting point gap with electronic ignition...

So will you need the dwell function for some other older vehicles you own? Or do you just need the tach function only?
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You have a lot more choices if you only need it as a tach.

I searched for "dwell meter" on a certain unspecified online shopping service named after a particular South American jungle. The first hit was the previously suggested Actron CP7605, which has the old school needle. There were also many inexpensive digital voltmeters with an automotive tachometer function.

 

I don't know if I would go with a digital meter.
I have seen it posted the digital moves to fast and can give false reading.


Unless I have a meter for volts & amps, dwell only if you need it but I only have 1 car I can use it on, I would go with the multi meter.


Going to show my age, for setting points, just to get it running use a match book cover, remember them?, as a feeler gauge.
Uni-set points for the most part were factory set and check dwell just to make sure it was right.
Dave ----

 

What purpose would a tach/dwell meter serve on a electronic ignition? I know you could use the tach, but I really never used one of those either. I know some people go by the book or the sticker on there radiator support, and if it says the idle is supposed to be 500 rpm, they set it to that no matter what. But I have never found this to be necessary, set it so it idles properly and doesn't bang into gear if it's a automatic, and that's it.

Do you really need to spend the money on this? I would spend the money on a timing light if you didn't have one. Or on a better one if yours is not working very well.

 

You answered your own question.
Not every one can set idle mixture or speed by ear.
Also when they are having issues and someone asks what is the idle RPM they can answer the question.


I also pointed out if the person did not have a volt/amp meter it would be best to get the multi meter and they only come with a dwell meter that I know of.
Dave ----

 

Yes you guys are correct, I only need the tach for this truck.

I wanted the dwell because I have two friends with dune buggies and I have had to set them both up (I can't tell you the number of VW's I've owned ... bugs, buggies, Thing, early 911 Porsche, 411, ....). All of these have points. Just seems I have to do one or two a year.

I just figured if I were spending the money on a tach then I may as well get a dwell meter also.

I have a good multi meter for ohms and volts. It's too bad it does not have an inductive pick-up. It has a frequency function ... would work as a tach if it could sense when #1 fires.

Anyway, just figured since mine died, I should replace it.

My original question was just how can one of these Sears meters "automatically" figure out if I have a 4, 6 or 8 cylinder? My best guess looking at the instructions online was that it picks up #1 using the inductive pick-up and the # of pulses per two revolutions off the coil with another connection ... and some how works it out. Could this be correct?

Thanks so much!!!!!!!!!!!

Mike

 

That sounds like a perfectly reasonable explanation. Gonna be a thoroughly boring forum, though, if everybody keeps answering their own questions...

Now if you really want a headscratcher, the emissions testing service in Washington used to have an RPM sensor that just sat on your hood. It was a small padded block, maybe the size of a coffee cup, with a cord that plugged into the test console. I asked the earnest young man running the machine how it worked. He said it picked up pulses from the alternator, but didn't know the details and didn't seem to care. He did place the sensor as close to the alternator as possible and it didn't work well until it was in close proximity. It was dead accurate compared to the tach on several vehicles I've owned, including my F250's 351W, a Chevrolet 4.3 V6, a Mitsubishi 4 cyl, and most surprisingly of all, a Mazda rotary. That engine had an ignition system more akin to a 2 cylinder 2-stroke with a total of 4 plugs. If that mystery sensor was somehow reading ignition pulses, I've got NO idea how it correctly interpreted that one...

 

I bought the analog Actron unit a long time ago, it works fine. Volts is self explanatory, the Tach has different scales. Plenty close. Once in a while it's useful to have analog meter for some voltage measurements, a digital unit can bounce around too much. Sometimes primitive test gear seems to work best for testing primitive gear...

The Dwell meter is the way to set points. The feeler gauge or matchbook setting on points is just to get the damn thing to start and run. Then, using the dwell meter, adjust the point gap at idle for 28-32 degrees (V-eight). Disregard at this .. point (heh) whatever the actual point gap ends up at, the specific points installed are now set exactly where they need to be.

Dwell actually refers to the amount of time the points spend closed, so consequently it is also the amount of time the coil spends charging back up, before the points open again and spill the beans. Basically we want that period to be as long as possible, for a hot ignition and best spark. Dual point distributors were a way engine designers tried to increase the effective dwell time on high RPM high output race engines. I checked the dwell on a Pertronix module installed for grins and it is a solid 32 degrees dwell angle.