Author Topic: Dwell Tach and timing light  (Read 20600 times)

Offline coolmercury

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Dwell Tach and timing light
« on: September 28, 2018, 09:04:23 AM »
Last items from last weeks auction, I needed a dwell tachometer and timing light so couldn't turn these down for $5.00.

Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #1 on: September 28, 2018, 09:10:47 AM »
The dwell/tach is a low-cost item, but the timing light is a great deal. At one time that light (with the advance dial adjustment) was quite and expensive item.

Thanks for sharing!

Offline bonneyman

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Re: Dwell Tach and timing light
« Reply #2 on: September 28, 2018, 10:12:20 AM »
The dwell/tach is a low-cost item, but the timing light is a great deal. At one time that light (with the advance dial adjustment) was quite and expensive item.

Thanks for sharing!

^^^ Yep!

Offline J.A.F.E.

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Re: Dwell Tach and timing light
« Reply #3 on: September 28, 2018, 10:52:23 AM »
Stuff looks hardly used.

Not used much anymore by most so they don't carry much value anymore but for $5 that's a steal.
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Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #4 on: September 28, 2018, 11:31:08 AM »
At one time that timing light was Sears best and a great piece of equipment. I have one myself. Very well done indeed!
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Offline slip knot

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Re: Dwell Tach and timing light
« Reply #5 on: September 28, 2018, 02:35:29 PM »
That's a nice timing light except for those disconnectable leads. Mine got loose and wouldn't make good contact. a wiggle or two and it would work...for a while... :(

Offline coolmercury

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Re: Dwell Tach and timing light
« Reply #6 on: September 28, 2018, 03:02:39 PM »
Both these still work fine, used them on the 56 Mercury a couple days ago. :)

Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #7 on: September 28, 2018, 03:04:21 PM »
That's a nice timing light except for those disconnectable leads. Mine got loose and wouldn't make good contact. a wiggle or two and it would work...for a while... :(

Same thing happened to the first one I had. I just looked around and found another that worked cheap and replaced it. I still like those guns.
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Offline bonneyman

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Re: Dwell Tach and timing light
« Reply #8 on: September 28, 2018, 10:09:15 PM »
Finally got a nice classic timing light, dwell tach meter, and  engine analyzer and now they're all useless because the Toyota is gone. The other two vehicles are newer, EFI.   >:(

Offline john k

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Re: Dwell Tach and timing light
« Reply #9 on: September 29, 2018, 12:01:20 AM »
Good stuff in their day, I wanted a light  like that so bad but couldn't afford it.    A good deal, but sort of like a chrome plated battery charger that is six volt only. 

Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #10 on: September 29, 2018, 05:20:48 AM »
Good stuff in their day, I wanted a light  like that so bad but couldn't afford it.    A good deal, but sort of like a chrome plated battery charger that is six volt only.

I wanted a light  like that so bad but couldn't afford it.  Story of my life, both single and married, especially married with kids.
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Offline lauver

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Re: Dwell Tach and timing light
« Reply #11 on: January 11, 2019, 09:35:46 PM »
Gang,

A couple of questions about old school dwell/tach's.

Will these tach's work on a 4 cyl with a little math?  If so, what's the correction on the 8 cyl rpm scale?

Also, regarding the timing lights, how do you use these on modern engines with no distributors and no high tension plug wires?

I have the old school equipment but have newer school vehicles...
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Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #12 on: January 11, 2019, 10:08:42 PM »
AFAIK -- modern vehicles can't be tested with the old analog devices. You need to connect to a high energy spark to trigger the magnetic pickup -- since coils are now directly connected to the plug, then it would take some Rube Goldberg engineering to get the pickup to trigger off the coil pack. The tach/dwell meter is useless in the same manner -- no distributor to hook up to.

The real old lights without the mag pickup were connected in series with the plug wire to the plug through a spring "T" fitting. If you can find one of those lights, and connect it after the coil and make the connection to the plug, then it might trigger the light.  -- BUT for what purpose?

IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)
« Last Edit: January 11, 2019, 10:18:37 PM by goodfellow »

Offline bonneyman

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Re: Dwell Tach and timing light
« Reply #13 on: January 11, 2019, 10:27:10 PM »
AFAIK -- modern vehicles can't be tested with the old analog devices. You need to connect to a high energy spark to trigger the magnetic pickup -- since coils are now directly connected to the plug, then it would take some Rube Goldberg engineering to get the pickup to trigger off the coil pack. The tach/dwell meter is useless in the same manner -- no distributor to hook up to.

The real old lights without the mag pickup were connected in series with the plug wire to the plug through a spring "T" fitting. If you can find one of those lights, and connect it after the coil and make the connection to the plug, then it might trigger the light.  -- BUT for what purpose?

IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)

Dang, Ray, is there anything you don't know about cars?  :D

Wish you were local - I'd bring my cars to you to fix ( when you had time in between your own 5 vehicles)!  :-[

Offline Matt_T

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Re: Dwell Tach and timing light
« Reply #14 on: January 12, 2019, 09:11:59 AM »
IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)

Doubling the scale values or halving the reading should work. I think. Been 20 years since I used a tach on anything bigger than a twin.

Offline J.A.F.E.

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Re: Dwell Tach and timing light
« Reply #15 on: January 12, 2019, 09:45:11 AM »
IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)

Doubling the scale values or halving the reading should work. I think. Been 20 years since I used a tach on anything bigger than a twin.

Exactly double the 8 cylinder reading.
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Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #16 on: January 12, 2019, 09:56:11 AM »
Man -- that brings back memories. Just for "kicks and giggles" I took a quick inventory of all the portable tach/dwell units I still have. Surprisingly there are a few.

I still have the first Dwell/Tach I ever bought back in the day. At that time there was a company Rite Autotronics Corp. (aka RAC) that dominated the DIY market with bargain test equipment and battery chargers -- all US made stuff, but definitely for the low end of the market. I still have the old vacuum gauge, compression tester, dwell/tach, and several nice battey chargers from RAC. The cheap RAC non-powered timing light went in the trash decades ago though.

This image is from the net, buy mine is in the same shape -- sitting in a box in the attic somewhere. First dwell/tach I ever owned that was exclusively mine. I usually had to borrow dad's or grandpa's when working on cars myself.





These others are sitting in the garage today --

Old Hawk -- tach/dwell/multimeter



Sun Automotive professional tach/dwell meter



Sears Automotive Engine Analyzer tach/dwell unit (perfect shape)



Stewart Warner handheld tach/dwell unit



Some of you older guys probably also have some of these things stashed away in boxes. The problem these days is trying to explain what these things were used for. Most kids have never seen a distributor -- or if they have, they've probably only  seen electronic distributors. They don't understand the technology associated with older point type systems.




« Last Edit: January 12, 2019, 09:58:50 AM by goodfellow »

Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #17 on: January 12, 2019, 10:13:44 AM »
BTW -- some may not know what a non-powered timing light is/was. Modern timing lights were hooked to the battery to provide power to the flash tube for a bright light. Original older professional lights, and later on less expensive lights, used the spark itself to power the light. It was simply hooked in series between the plug wire and the plug. Problem was that in non-high energy (regular) ignitions the light flash was so faint as to be almost invisible. Some professional lights from the early days that used the same technology actually included a hood to drape over the engine to create a "dark room" effect for the flash to become more visible.

Found this on the web. RAC made these cheap lights for their intro tune up kits -- circled in red. Notice the lack of battery hookup clips.



« Last Edit: January 12, 2019, 11:20:51 AM by goodfellow »

Offline oldnslo

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Re: Dwell Tach and timing light
« Reply #18 on: January 12, 2019, 11:01:38 AM »
I spy with my little eye....a battery hydrometer and filler bulb. Both of which have seen zero use on my end in a decade. Even in the southwest, I'm not adding fluid to a battery.

Just like the dodo bird, and the oil filler spout for metal oil cans....these things fade away.

I too have that RAC dwell/tach (and higher end units), tho mine is proudly branded JC Penneys and is grey. Ha!

Offline lauver

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Re: Dwell Tach and timing light
« Reply #19 on: January 12, 2019, 01:58:35 PM »
AFAIK -- modern vehicles can't be tested with the old analog devices. You need to connect to a high energy spark to trigger the magnetic pickup -- since coils are now directly connected to the plug, then it would take some Rube Goldberg engineering to get the pickup to trigger off the coil pack. The tach/dwell meter is useless in the same manner -- no distributor to hook up to.

The real old lights without the mag pickup were connected in series with the plug wire to the plug through a spring "T" fitting. If you can find one of those lights, and connect it after the coil and make the connection to the plug, then it might trigger the light.  -- BUT for what purpose?

IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)

GF-- Thanks for the info, I get it.  I have no tachometer in my 2003 Tacoma... it's the standard cab model with no frills.  So, my option would be to get a scanner, connect up to the ECU port and get live readings (engine running) on the scanner?  What if I wanted to add a tachometer in the vehicle?  Is there a connection on the ECU that I could tap?  Or, is there an unused wire for a tach in the wiring loom under the dash? 
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Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #20 on: January 12, 2019, 02:21:09 PM »
There are a lot of options for adding a tach to modern vehicles. Usually you have to find a switched power source, a ground, a lighting power source, and then a line to the ignition module, or some high tech units use a pass thru connector on the OBDII port to get the data directly from the computer.

Offline slip knot

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Re: Dwell Tach and timing light
« Reply #21 on: January 12, 2019, 02:28:38 PM »
I use the dwell/tach more than the timing light on these old tractors. get the points right and set the timing by ear. if it rattles under load back it off just a tad. ;D

Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #22 on: January 12, 2019, 03:39:24 PM »
AFAIK -- modern vehicles can't be tested with the old analog devices. You need to connect to a high energy spark to trigger the magnetic pickup -- since coils are now directly connected to the plug, then it would take some Rube Goldberg engineering to get the pickup to trigger off the coil pack. The tach/dwell meter is useless in the same manner -- no distributor to hook up to.

The real old lights without the mag pickup were connected in series with the plug wire to the plug through a spring "T" fitting. If you can find one of those lights, and connect it after the coil and make the connection to the plug, then it might trigger the light.  -- BUT for what purpose?

IIRC -- you got a 4cyl reading on the Dwell Tach by doubling the value on the 8cyl scale. -- It's been a while since I've used one of the handheld models though --  :)

That Craftsman light shown does have the magnetic pickup clamp for #1 wire. I use mine for up to 1986 GMC just fine. I cannot speak to newer that that application.
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Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #23 on: January 12, 2019, 03:43:23 PM »
BTW -- some may not know what a non-powered timing light is/was. Modern timing lights were hooked to the battery to provide power to the flash tube for a bright light. Original older professional lights, and later on less expensive lights, used the spark itself to power the light. It was simply hooked in series between the plug wire and the plug. Problem was that in non-high energy (regular) ignitions the light flash was so faint as to be almost invisible. Some professional lights from the early days that used the same technology actually included a hood to drape over the engine to create a "dark room" effect for the flash to become more visible.

Found this on the web. RAC made these cheap lights for their intro tune up kits -- circled in red. Notice the lack of battery hookup clips.



I have one or two that look like the one circled that are supposed to be suitable for 6volt applications like early Ford V-8 IE (flathead) I also have several twins to the ones Ray showed floating around the shop myself. Too cold and I am not heading to the shop for pics to share, sorry guys.
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Offline Elroy

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Re: Dwell Tach and timing light
« Reply #24 on: January 12, 2019, 04:11:09 PM »
Last items from last weeks auction, I needed a dwell tachometer and timing light so couldn't turn these down for $5.00.

That was a great deal

At one time that light (with the advance dial adjustment) was quite and expensive item.

They weren't cheap but they were were a fairly good timing light.



The adjustable advance feature is what sold Elroy back in the day





This thread had Elroy digging out the antiques



This decal should date it well





 
« Last Edit: January 12, 2019, 04:12:52 PM by Elroy »

Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #25 on: January 12, 2019, 04:17:33 PM »
Were those from back in Elroys "hair" days?  :))
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Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #26 on: January 12, 2019, 04:20:41 PM »
For those who weren't around then. "The CAMFather" was Ed Iskenderian -- ISKY Cams. Isky grinds are legendary.

Offline Elroy

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Re: Dwell Tach and timing light
« Reply #27 on: January 12, 2019, 04:22:12 PM »
Were those from back in Elroys "hair" days?  :))

Probably

Prior to the "mag pick-up" , Elroy had a light that required physically tapping into the high tension lead with a spring type adapter.  It sucked as it was tricky and would usually ground out.
Elroy still uses the mag-pick up light on his 85 Mustang.

Offline Uncle Buck

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Re: Dwell Tach and timing light
« Reply #28 on: January 12, 2019, 04:46:34 PM »
I recall pop had a golf T he used to plug to vacuum advance hose when timing and setting dwell back in the day.
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Offline J.A.F.E.

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Re: Dwell Tach and timing light
« Reply #29 on: January 12, 2019, 05:06:19 PM »
I use the dwell/tach more than the timing light on these old tractors. get the points right and set the timing by ear. if it rattles under load back it off just a tad. ;D

At least the early air cooled VW's were timed that way although there was a timing mark on the pulley that used the case split as a pointer. I still time the Spitfire that way as well even though I have at least three timing lights.
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Offline bmwrd0

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Re: Dwell Tach and timing light
« Reply #30 on: January 12, 2019, 08:12:47 PM »
I recall pop had a golf T he used to plug to vacuum advance hose when timing and setting dwell back in the day.
They taught us that in high school.

Offline lauver

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Re: Dwell Tach and timing light
« Reply #31 on: January 12, 2019, 11:43:24 PM »
Gang,

I still have 3 golf T's in my machinist chest (i.e. my first tool box ever, back in the 1960's) that I used to plug rubber vacuum & rubber gas tubing.

This thread has brought back all kinds of memories of the good old days when life was simpler.

Thanks guys.
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Offline stokester

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Re: Dwell Tach and timing light
« Reply #32 on: January 13, 2019, 01:37:47 PM »
Like many here I started with the very basic moved to the better stuff when I could afford it.

I static timed my '66 VW Bus using a test lamp with the original "Idiot Book" nearby.  A bit later I bought the cheapest Sun timing light without an inductive pickup where a spring device was inserted between the plug and wire - what a PITA.  On a trip to visit one of my VW mentors he showed me how to use the dial-in advance light and I saved up and bought the Sears one so I could do maximum advance without a degree wheel.  Its only use these days is on the '70 and '74 Bugs and my BMW Airheads.

The Mac meter was a later purchase at a sale and the Allstate vacuum and compression gauges were from a friend cleaning out her garage.  You'll also see one of those unpowered timing lights which I've never tried to use.
Nick
Yorktown, VA

Offline goodfellow

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Re: Dwell Tach and timing light
« Reply #33 on: January 13, 2019, 01:43:10 PM »
Nice Nick! That MAC analyzer was quite "the bomb" back in the day. I don't recall who make it (although I think it may have been Fox Valley) -- but it was a fixture in many pro tool boxes.

 

Offline slip knot

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Re: Dwell Tach and timing light
« Reply #34 on: January 13, 2019, 05:54:03 PM »
the unpowered timing lights were great for working on small engines and equipment. I had several but they were lost when the toolbox got stolen. still very handy to have.

Offline DeadNutz

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Re: Dwell Tach and timing light
« Reply #35 on: January 14, 2019, 10:25:26 AM »
I use the dwell/tach more than the timing light on these old tractors. get the points right and set the timing by ear. if it rattles under load back it off just a tad. ;D

At least the early air cooled VW's were timed that way although there was a timing mark on the pulley that used the case split as a pointer. I still time the Spitfire that way as well even though I have at least three timing lights.

It was easy to adjust the timing on my VW powered sandrail. The straight exhaust was plenty loud to let you know when it was just right. The crank pulley with the degrees marked all around it was just for decoration.

Offline stokester

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Re: Dwell Tach and timing light
« Reply #36 on: January 20, 2019, 02:50:10 PM »


It was easy to adjust the timing on my VW powered sandrail. The straight exhaust was plenty loud to let you know when it was just right. The crank pulley with the degrees marked all around it was just for decoration.
[/quote]

It is also an asset to have the calibrated nose to know if the air-cooled VW was running hot.  I trained my daughters to recognize the normal engine smell and recognize if it smelled hot, then to slow down and of course, tell Dad.  Another good indication was if the dipstick was too hot to check the oil after a run then it was either being run too fast or there was too much advance.
Nick
Yorktown, VA