Digital dwell meter hook up

[fizeus]

Hi all,
I'm looking for some gentleman can tell how to hook up a digital dwell meter to set dwell on my Bosch dizzy. (Analog dwell meters was out of stock)

I've searched around and i think i have to put the black cable from the meter to the ground and the red cable from the meter to the low tension cable coming from the coil and going to the distributor.... at least according to the dwell meter manual.

Right or wrong? i'm confused and paranoied... and aboveall this is my fist attempt in dwell setting.

Can anyone please describe how to hookup the meter correctly to avoid damages to car, to the meter and to me ?

I'd love some photos to fully quit my paranoia.

The car is a stock carburated with Zenith 911 T from 1973 with a Dizzy Bosch distributor.

Thanks in advance to anyone can help

[E Sully]

If you give us the model of meter you are using, perhaps we can help.

[E Sully]

This is from Pelicans technical article on adjusting points and timing.
"You can measure the dwell angle on 1965-68 911s by hooking your meter up to the positive and negative terminals of the coil. On 1969-1977 911s, you will need to use a different technique since the capacitive discharge system won't give you an accurate signal. Don't hook up the dwell meter to the coil, or you may damage your capacitive discharge system and your meter. Instead, hook the signal wire to the dwell meter directly to the points wire that is coming off of the distributor. In some cases, it may be easiest to hook the dwell meter to a long screwdriver and place the tip of the screwdriver on the contacts where the wire is plugged into the distributor. You should be able to get an accurate reading from the distributor using this method."

[fizeus]

E Sully, thank you for your kind reply.

My Multimeter is an UNI-T UT107 and the english manual is available here.
If you open it you should be at the dwell metering page.

K. Dwell Testing - Uni-t UT107 Operating Manual [Page 28]


You also provided me very useful informations about how to hook up the dwell meter.

hook the signal wire to the dwell meter directly to the points wire that is coming off of the distributor.

So basically I have to plug the Multimeter RED cable to the plug coming off the distributor (green circle in the photo below) and the black cable of the multimeter to the ground (fan shroud). Right ? Do I understood well ?


Excuse for the newbie question but it’s the fist time I’m messing with distributor and I prefer to not damage my baby.
I Hope you can understand me

[HarryD]

^^

That is where I hooked my dwell/tach meter for my 911. Right on the dizzy.

[fizeus]

Thank you HarryD ! :-)

[fizeus]

How this story ends:

After years honoured work I trashed distributor points, rotor, cap, plug cables and obviously spark plugs replacing them with new ones.

Following members tips I setted dwell and checked timing this week-end.

In my Bosch distributor (dizzy) a 0.35 mm gap exactly correspond to 37.9 dwell angle and it seems steady through various RPMs.
I also checked timing and advance with a timing light and now all is in specs.
(timing seems a little bit unsteady in 850-1050 RPMs range but I assume it's normal for a 40 Y.O. unrebuilt distributor to have an oscillation of 3-4 degrees).

I also did a little ride, about 40Km...
Only now I can understand why you always tell to check dwell and timing!!
The engine now is very responsive, small hesitations under acceleration are gone and it perform very well over 5K RPMs (previously the engine feels sluggish), also in 5th gear the engine has a veeeery good progression.
(There are just some pops in the exhaust in 3.2-3.0 RPMs on decel but I’ll investigate the problem later)

All this story to say “thank you” to all the people on the forum helped me, replying to, my sometime stupid, questions.

Your happy driver
fizeus

[E Sully]

Nice to hear it is running well. Adjusting points and timing regularly is important. Distributors can also wear out and develop play causing timing issues if not maintained. Make sure to add a couple of drops of oil to the felt under the rotor, and apply a small amount of points grease on the lobe. Apply just a little, you don't want it getting on the points.

[HarryD]

Originally Posted by E Sully

Nice to hear it is running well. Adjusting points and timing regularly is important. Distributors can also wear out and develop play causing timing issues if not maintained. Make sure to add a couple of drops of oil to the felt under the rotor, and apply a small amount of points grease on the lobe. Apply just a little, you don't want it getting on the points.

Just to emphasize.

Any light oil (3 in 1 is good) for under the felt.

Get Distributor Grease for the lobe. Bosch has a tube you can get. One tube will last a lifetime.

[fizeus]

I oiled the felt using traditional engine oil (20W50) and I think it should be ok.
(Repeated the oiling procedure 2 times, just to be sure!)

Unfortunately Bosh grease is hard to find here, I used the CV joint grease (it's black) even if I read on the forum that it's better to use Bosch Grease because it's developed to resist to high temperature (and after 20 min the lobe seems to be very very hot... ask me how I know!!)

I think I'll end up ordering it from ebay !