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View Full Version : I dug an old Dwell Meter,....Now what?



Stinky
07-27-2004, 02:42 PM
Since my TR6 is scheduled to picked up in about 17 days,...I've been going thru some old car stuff which I have'nt looked at in many years.
I ran across a combination Dwell, Points, and Tach meter.
Now that I've got a TR6 on the way,...I figure I can put this thing to use. Problem is I don't remember how to hook it up....:(
It has a 3 way switch that will change it from Dwell, to Points, or Tach. That's pretty easy,...but it only has 2 wires coming out of it, one has a red alligator clip, and the other wire has a black clip. There are no other plugs, or ports on the meter,...so apparently it works off those 2 clips.
Can someone clue me in as to where to hook the clips to make this thing work for the 3 different processes?

Thanks in advance /ubbthreads/images/graemlins/confused.gif

Geo Hahn
07-27-2004, 03:01 PM
I think the red would go to the dizzy side of the coil and the black to ground. Does it also have a switch for selecting 6 or 8 cylinders (or maybe just 2 scales and you read the appropriate one)?

Actually, I doubt this is going to be the favorite tool in your toolbox -- I have never used one on a British car just 'cause there are simpler ways to set the points & timing.

Bugeye58
07-27-2004, 03:24 PM
They are handy as an underhood tach while setting idle speed though. And I think the "Points" function is an ohmmeter. I'll have to see if I can find mine, and take a look.
Jeff

Simon TR4a
07-27-2004, 03:57 PM
I would suggest there should also be a small clamp at the end of a cable in order to clamp to one of your plug wires, this then flashes the strobe light which you point at the timing scale on the front pulley.
If that's missing I'm not sure how it would work, I assume the red and black go to your battery terminals for power and ground!
Simon.

Bugeye58
07-27-2004, 04:23 PM
Simon, DWELL METER, not a timing light.
Jeff

Stinky
07-27-2004, 04:55 PM
I'm guessing the red lead goes to the dizzy(distributor) side of the coil,...and the black must be ground. My problem is where does the meter get it's power from?
I have a larger engine anylizer and that one has a red and black that clip to the battery, then a green lead that goes to the Dizzy side of the coil.
That engine anylizer is large and bulky,...I'd like to figure this smaller unit out. It's something I could leave in the trunk of the car with some other tools.
I suppose I'll have to wait...17 days, and 8 hours to try it out on the TR6 I'm getting. Everything else I have has electronic ignition.

SilentUnicorn
07-27-2004, 05:10 PM
you wouldnt happen to have a picture of it?

mark

07-27-2004, 05:12 PM
Stinky,
Thank god for dwell meters. I challenge anyone to set the points perfectly with a feeler gauge. Set the dwell at 35 on your TR6 and you will be running right on. black-ground, green-coil. And bit of advice from someone that has bad luck (this topic has been broached many times) with electronic ignition on LBC's: don't do it!

Bill

Stinky
07-27-2004, 05:30 PM
I have a pic,...let me see if I can get it uploaded here.

Looks like you're gonna have to click where it says "Attachment" above

Bugeye58
07-27-2004, 06:21 PM
Stinky, the power comes from the low tension side, (dizzy) of the coil. And, you've got the wiring figured out.
Jeff

Stinky
07-27-2004, 06:36 PM
Thanks Bugeye /ubbthreads/images/graemlins/smile.gif

Bugeye58
07-27-2004, 06:55 PM
Stinky, just one thing to remember is that if you are adjusting the dwell while cranking the engine over, remove the distributor rotor. If you don't, it hits the screwdriver you are using to adjust the points with a nasty " crack ", and then falls someplace in pieces.
Of course, I have only heard this story, and can't verify that it's true! /ubbthreads/images/graemlins/grin.gif
Jeff

Stinky
07-27-2004, 09:39 PM
So I can't adjust the dwell with the motor running?

Bugeye58
07-27-2004, 09:49 PM
Nope, as you have to remove the distributor cap to get to the points. You can do it by just spinning the engine over with the starter.
The only engine I ever saw that you could adjust the dwell on a running engine was the GM with the trap door in the distributor cap. One of the smartest things I ever saw GM do.
Jeff

Geo Hahn
07-27-2004, 10:56 PM
[quote...The only engine I ever saw that you could adjust the dwell on a running engine was the GM with the trap door in the distributor cap...

[/ QUOTE ]

I was trying to recall why I had used one of these years ago -- was my girlfriend's (now wife) '73 Camaro. Seems like you fitted an allen wrench or some special purpose wrench in there to adjust. I agree, a useful feature.

Bugeye58
07-28-2004, 06:24 AM
George, the special tool was essentially a 1/8" Allen wrench grafted to a short piece of speedo cable, and attached to an insulated handle. If you just used an Allen wrench, there was a good chance you would wind up getting knocked on your butt!
Jeff

Dave Russell
07-30-2004, 06:39 PM
[ QUOTE ]
Stinky,
Thank god for dwell meters. I challenge anyone to set the points perfectly with a feeler gauge. Set the dwell at 35 on your TR6 and you will be running right on.
Bill

[/ QUOTE ]
Dr. Bill,

I think you are overstating the importance of dwell in it's effect on engine performance. A .004" error in point gap setting would only change the dwell by about five degrees.

To put dwell into perspective, on a six cylinder engine, running at 5000 rpm, a dwell setting of 35 degrees would give a point closed time of about .00233 seconds or 2.33 milliseconds. Reducing the dwell to 30 degrees would give a point closed time of .002 seconds or 2.0 miliseconds. This decrease in dwell time would reduce the available secondary spark voltage by about 2%. Hardly enough to be detectable.

This same 5 degree dwell error WILL change the initial timing by about 2.5 degrees. So if anything needs to be adjusted it would be the initial timing. How many timing lights are accurate to 2 degrees.

If you have experienced difficulty with the effect of dwell on engine performance, I suggest you look elsewhere for the problem. It will have no noticeable effect on engine performance until it gets off by about 10 degrees or about .008" point gap. certainly easy enough to detect with a feeler gage.
D

07-30-2004, 07:16 PM
Dave,
I find that an arbitrary setting of my points using a feeler gauge is at best a starting point. By arbitrary, the selected gauge is only as good as the gauger, namely me. Alot has to do with the integrity of my gauge and integrity of my points and the absolute accuracy of the flat surfaces and their approximation. Some people can stick the equivilant of a beer pop top between the point surfaces and get what they feel are good results. I find it much more gratifying for me to set the points, knowing that all the variables can cause me to get a less than good result. Many a time I have set them and find that I did a lousy job when checking with my trusty dwell meter. I use it as a confirmation and it makes me feel good. Isn't that what LBC's are all about. When I get into my Tahoe, the only thing that makes me feel good is if the AC is working. I just like fooling with my little baby.

Bill

07-30-2004, 07:17 PM
You ought to see my set my valves. You would think that I was a dentist or something.....

Bill