TheSamba.com :: View topic

Mon Jul 16, 2012 5:30 pm

Hi guys. I'm a newbie to the VW world but getting better but totally new to a Dwell meter. I have one now but it has three connections while most I see here seem to have two. I want to check my Dwell, and use the tach function to set my carb. First of all heres a pic...

I am thinking the Red lead goes to the green wire on the coil. The black lead goes to a ground. The nut on the coil to the housing seems to be a popular choice. But where does the last go if anywhere. In the little booklet that's with it says on the number 1 plug wire, but I haven't seen that in the stuff I'm reading. So I'm just trying to be sure. Anyone know?

Ryan

Mon Jul 16, 2012 6:04 pm

My guess:

Red to positive (like coil positive, not where the green wire is). Black to ground. The sensor lead likely goes either on coil to center of distributor, or on a spark plug wire.

My dwell meter is different, has positive, negagative, and then a green sensor wire which goes to green wire connection on coil negative side.

Be patient, someone will know for sure. Did you try a google search for the manufacturer?

Mon Jul 16, 2012 6:42 pm

Looks like you're missing a 3rd wire wih an alligator clip to connect to the coil. I could be wrong, but I am not sure how that inductive pickup would help with dwell.

I found this description of what you've got on toolsource.com "Equus Products Replacement Inductive Pickup w/out Green Clip for Dwell"

but I can't find a pic of the green clip on Google. Weird.

Mon Jul 16, 2012 6:45 pm

My dwell/tach only has two clips. One to coil and one to ground.

Mon Jul 16, 2012 8:44 pm

If I saw this sooner I could have dropped off my dwell meter to you today. Ill be out Thursday if you want to borrow it then.

Tue Jul 17, 2012 6:53 am

I've seen a meter similar to that before. You are correct that the large black thing is an inductive pickup. Yours "looks" broken and missing part of the clamp that keeps it wrapped around the plug wire. If the key part of the magnetic pickup is still in the remaining portion picture pickup it might still work (Use a rubber band to keep the wire in the small slot).
The pickup will detect the pulse of the #1 spark plug wire and register this as "one revolution". By measuring these pulses the meter can determine the engine rpm. This is how the meter measures RPM.

The red and black clips are used the same way as most dwell meters. Black is ground and red goes to the #1 terminal (-) of the coil. This is how the meter measures dwell.

Tue Jul 17, 2012 6:56 am

Hi Ryan,

I have the same meter as you including the manual for it. The Black Clip goes to a ground (-), the red goes to the negative (-) on the ignition coil. The inductive lead is not used to read Dwell.

If you send me your e-mail address I will copy and email you the manual. If you prefer and you send me your mailing address I will mail you a copy.

My email address is: [email protected]

regards

Ron

Tue Jul 17, 2012 8:29 am

Ashman, the pickup isn't broken actually it just slides back inside when not in use and slides back up when on the wire.

Gitchigumi, I do have a manual but of course it does t look like a bug lol. Let me jut ask this though. The ground I know. The red wire goes to the coil. Does it clip to the green wire or the other side? Also does the clip need to be on number one plug wire for both or neither?

Ryan

Tue Jul 17, 2012 8:59 am

its missing parts
look at that dirty face.. clean it.
but it measure volts. and ohms.... (found a clean one on ebay)
so the black goes to the body of car. ground
the red goes to battery , or to #15 coil lug , dont ground that lug or 15 catches fire, (no fuse) ground btw is just 1/4" from here,,,, boom.

then it shows a scale for resistance, that alone proves that the mag pickup
is not used for that, so you are missing wires..

the missing wire, is the coil minus lug wire, green or called #1 by VW and DIN.

the instructions would have all these facts.
RPM = mag
Dwell, = test lead X
volts, =red and black. to battery ground. these 2 wires power the meter too.
ohms, = RTM ,it will say. read it.

possible 2,(lots of ways to do things in electronics)
the mag pick-up may be so sensitive to pick up the points current.
it's not hard to do that , at all (a few turns of wire and ferrite core)
and may just work that way. seems so...
maybe the only way.
but the ohms has me baffled.? but not really..

but here is one theory... the current pickup measures amps.(sure does)
so R = E/I (good old ohms LAW) E means volts to a tech.

12/2 = 6 ohms. (12 is a constant ,the battery? sure but...)

6 ohms is the total combined resistance from points , coil and ballast.
R1 + R2 +R3 = R total.

the voltage is easy , the red and black clips are on power. so volts is power feed voltage from #15 to ground. I bet this meter has NO BATTERIES.

so 12v is not a constant it is measured, full time.
Red and black clips. so those clips do 2 things, power the unit and are measured.

ive worked in a instrument test and repair lab and seen most every trick in book
but reverse engineering from a photo. your kidding, right>? but tried.... i did.

short answer,
red to battery + (how you do that is your call) (coil + (15) IS IFFY.
minus to battery - ( how to you that is your call) body ground works.

YOU DO KNOW , that many bugs have ballasts resistor to the 15 lug on coil
right and if so, the meter WILL FAIL. see why?
answer, its not at 12v !

the clip (telescoping, love that idea) is to the GREEN points wire.

the tach is nice, but i have no need for dwell ever, my cam is square and
points are at .016" is ALL THAT matters, dwell wise. DWELL is not critical unless user is OCD to the max. RTM , its a FACT.

I use an optical hand tach in the back and a real tach in the dash.
I'd spend the cash on a nicer timing light... or gages.
my hand tach can check any spinning object is and for more usefull.

nice unit, too bad they dont make them now.

Tue Jul 17, 2012 9:57 am

Hi Ryan,

Yes, the red goes to the green wire that runs between the coil and the distributor. You can clip it to the coil end of the wire.

ron

Tue Jul 17, 2012 10:46 am

ron , you guessing. or have one.
?
the poster would do better posting his instruction manual
send it to me and ill pdf the thing and add help clouds. too.

but the net shows zero manuals.... not that i can find...

it is a black box, until that is done. its even black.

i have NITRO publisher, so ,.... can do it.

Tue Jul 17, 2012 10:51 am

the poster
has the manual
and asks use to read it and tell him what it means , unseen. ouch

he says, it dont look like a bug. (took me 10 reads to figure that)
sure............

that means the diagrams in the instructions show normal cars
cars with battery in front and motor in the front.
is that a surprise?

what you forgot to say was?, what did it show with the diagrams?
where was that red clip? on that V8 detroit iron (guessing drawings...)
and
where was that black wire clip,,,,
if you had stated that, then all this speculation will end now.

my wild guess is,

red battery +
black battery -
clip to points wire..... magnetic clip.
am i right. and if wrong correct me... .you have the book , not we.
and google shows zip. meaning they are RARE.

not saying i know ! but with just a little more input. bingo

Tue Jul 17, 2012 5:10 pm

Here you go gentlemen. This seems to be the related topics I'm trying to use...

Ryan

Tue Jul 17, 2012 7:26 pm

Yep, the page with the 3 pics of the points is page 11 of the manual.

Wed Jul 18, 2012 5:45 am

Ryan,

Just a follow up to the discussion about the dwell meter. If checking dwell you don't have to connect the inductive pick up. The meter reads the electrical impluse sent by the coil to the distributor via the green wire and converts it into a degree reading on the meter. You will note that the meter has a 4cyl, 6cyl and 8 cyl scale on it. If using as a tach, then you hook the inductive pickup to the number 1 cylinder spark plug lead. The pickup has an image of a sparkplug on it which goes to the spark plug side when hooking up. If you are measuring volts then the black is (-) and the red is (+). Ashman described this in his response.

You don't have to actually start the engine to check the dwell. The digital meter I now use, instructs to remove the high tension wire from the coil to the distributor and ground it and then turn the engine over to get your dwell reading. You can actually keep the distributor cap off when doing this as all you are doing is measuring the opening and closing of the points.

As was pointed out by candymustang66, if your set up is stock, and the lobes on the distributor shaft are nice and square (corners are rounded a bit though) and you set your points to .016" your dwell will be well within spec.

Not surprised we can't find the manual on-line. I bought my meter in 1975 or so, when I owned a 68 vdub, which to me doesn't seem like a long time ago but I have to remind myself that's almost 40 years ago. Guess I'm getting old!

ron

Ron

Wed Jul 18, 2012 10:36 am

Forgot to mention that if you don't actually start the car you at least have to have the ignition key turned on so the coil receives power.