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Thu Nov 06, 2008 10:51 am

I just got an old Mac Tools ET 805 analog dwell meter and I want to do my tuning right.

Do you plug off the vacuum canister and carb on all vacuum advance dizzy's? Mine is a '62 big cap.

Am I correct in using the red lead wire on the dwell meter to the dizzy side, terminal 1, of the coil and the other to ground?

Is the following process in order

1. Valve Adjustment
2. Points
3. Dwell
4. Timing
5. Carb Adjustment

I've been through a ton of searches and can't get all my questions answered.

Thu Nov 06, 2008 11:30 am

This really old timey unit I still have that I used back in the 70's worked this way: There's a red lead (battery cable type for jumping) that goes to the + on the coil, a yellow alligator clip that goes on the - on the coil, and a black lead like the red that grounds to a suitable source. Then you select amps, volts, points, dwell, hi rpms or low rpms, but you have to select 4-8 cyl rather than 6. "4 cyl rpm and dwell, double 8 cyl. readings." This little unit still works fine if you like the wavy indicator needle types. Now, if you're working with a 6V system, I'm not sure if my suggestions are appropriate with an old analog meter like what you may have. Mine are for 12V.

Thu Nov 06, 2008 11:42 am

I like analog tach/dwell meters, they usually are a lot smoother reading than digital ones. Make sure the needle is "zeroed" - there's probably a little screw that allows you to set the zero point of the gauge.

Does it have a 4-cylinder scale on it, as mentioned above?

That's a two wire gauge, as far as I can tell from the one picture of one I saw on eBay of such a meter. That one should work fine on both 6V and 12V systems. So yeah, red to terminal 1 on the coil, black to a good ground. I find the stock chrome bumper on my 62 works OK as a ground.

I go to around 47° of dwell - earlier books said 50, but later on VW changed that to 47 +/- 3 degrees. And as the dwell often increases slightly over time as the contact block wears, I like to start it out on the lower side.

Your order of operations is right. Valve adjust with a cold engine. If you're putting in new points, do that, I set them to about .017 as a baseline, and static time to close to where it needs to be. Start engine, let warm up, check valve covers for leaks. Then throw on the dwell meter and check that. Adjust it as needed to get it around 47°. Then dial in your timing and then your carb for idle speed and mixture if needed.

-Andy

Thu Nov 06, 2008 12:03 pm

Thanks Jody and Andy,

It's not here yet. Just bought it off Ebay, but it does have the 4 cylinder setting. Jody you said the + side of the coil. Is that terminal 1? Maybe I've got it mixed up, but read t attach to the dizzy side which I thought was the - minus?

Andy it does have the screw to zero in. I'm going to have to use old points until I can get a set. The big cap 2 piece sets are hard to find.

What about plugging off my vacuum canister and carb? I think I'm supposed to do this

Thanks a Lot Guys.

Lou

Thu Nov 06, 2008 12:12 pm

Vacuum does not change dwell. That only matters for timing.

Zero the gauge in the position at which you will be reading it. In other words, don't zero it flat on the bench and then take a reading shiel holding it vertical. The zero pint will often change.

It connects to the small coil wire that goes to the distributor, not the other side.

Thu Nov 06, 2008 12:20 pm

I set the dwell with an analog gauge once. The engine ran for a while then cut out on me. I reset the points gap to .016 and it's been fine ever since.

Thu Nov 06, 2008 12:20 pm

Thanks for all the good advice. The Samba forum is better than have an old dealership of certified mechanics.

Thu Nov 06, 2008 12:25 pm

If your points are new, the feeler blade method works fine. If they get a tit on the moving part this is no longer accurate. The dwell meter works for both.

Thu Nov 06, 2008 12:26 pm

My old tach/dwell unit attaches like this:

Red to positive source, either battery or to the coil 12 volt positive connection, usually on the outer (driver) side of the coil, wires there continue to electrojet on carb and to carb choke heater.

Green to the coil terminal (usually a green wire) which goes directly to the distributor.

Black to engine ground.

Thu Nov 06, 2008 12:53 pm

Jody,
Re-read your post and your right. I wasn't thinking about the lead for battery cable. It does, I believe, have 3 leads.

lou

Thu Nov 06, 2008 1:38 pm

Try hitting the Mac Tools web site for a user manual in PDF. Ya never know. They may still exist.

Thu Nov 06, 2008 1:45 pm

Will do--- Thanks

Thu Nov 06, 2008 2:08 pm

Oh it does have three leads? It's possible that you might not need to hook all 3 up, as sometimes you don't need the 3rd to read tach/dwell - the signal from the coil powers the gauge on those settings.

Thu Nov 06, 2008 2:42 pm

Andy,

I believe it has 3, but could be wrong as I've only seen a not too clear photo. I e-mailed Mac Tools to see if they have a manual electronically stored. Nothing on their website of PDF files. I'm not that good on electronics, so I'm sure I'll ask more questions when I get it.

lou

Wed Nov 12, 2008 6:11 pm

[img]http://www.flickr.com/photos/7682942@N03/3026429840/[/img]

[img]http://www.flickr.com/photos/7682942@N03/3026429846/in/photostream/[/img]

Hey Guys,

I got the Mac Tools dwell meter in finally. It has 2 wires. A black one and a green one. I am assuming the green goes to the - side of the coil and the black to ground for dwell. It has three settings. Volts, Dwell & RPM. Where do the wires clip to on volts and rpm's?

I hope these images come up

Wed Nov 12, 2008 7:08 pm

Ha, I thought it was only two wires on that one I looked up on eBay.

Black is probably ground and green to terminal 1 "-" side of the coil. That will give you dwell and tachometer (RPM) readings. For voltage, probably black for ground and green for the voltage input.

Okay, time for the photo lesson. :D

For images to come up, you'll have to have them displaying on your screen, then you right-click on the images, and select Properties - then a box should pop up with a different URL of just the image. If that URL ends in an image extenstion like jpg, gif, bmp, then it will work to display it here on the forums. In your case I see the URL ends in ".jpg?v=0" - you have to get rid of that extra question mark V = 0 stuff. Here's your pics, and I'll include the bare URLs as well so you can see what they look like.

-Andy

http://farm4.static.flickr.com/3153/3026429840_b14fae7bc4.jpg

http://farm4.static.flickr.com/3165/3026429846_21d5cd469f.jpg

Wed Nov 12, 2008 7:15 pm

Thanks Andy,

I'll make sure I follow your directions on posting photos. Only excuse I've got is I'm old, but still trainable at 69--I think.

I'll check out the meter tomorow evening.

Lou

Fri Nov 14, 2008 8:45 am

Well it works, but as Jody mentioned the needle is wavy and it bounces from 25 to 30 degrees at idle. If I had to adjust the points just a small amount, I would not be able to do it accurately.

Do all dwell meters do this?

lou

Fri Nov 14, 2008 9:14 am

I've never had a meter like yours, but in my experience with other types, analog dwell meters usually do not bounce (RPM, of course, will) But my little analog dwell meters, as shown below, the only time I've seen variation is when the dwell really was varying, usually when revving it up, with the old wobbly breaker plate syndrome. I just used this to check the dwell on my baja bug the other day.

Fri Nov 14, 2008 9:40 am

Thanks Andy,

I also can't adjust the needle to zero either, but that's the way it goes sometimes.

Lou