Dwell angle and CDS - HOW???

TSwede · 06-28-2004, 06:35 AM

Hi all - i know this is a well battered subject but here it is anyway - there might be someone who can enlighten me -

I have a 75 911s (CDS) and want to check the dwell

I am aware that with CDS I connect the meter (Gunson Autoranger) to the dist. and earth (according to threads and Haynes..)

I tried this and the engine started stalling - did it a couple more times to the same effect..

The 2 questions are as follows -

1) does anyone know the Gunson Autoranger - it has 3 leads - Red, Black and Blue... so is it something to do with how I am connecting it up - the instructions are ambiguous at best..

2) am I connecting to the right bit of the dist.. I am connecting to the terminal on the outside that connects to the points on the inside - it is the only terminal I can see (Bosch Dist)...

I've just put the points on and would love to get it bang on for once..

Ta All

rlane · 06-28-2004, 07:28 AM

I am not familiar with the Gunson...with my meter you just put the black to engine ground and red to the trigger (the connector on the outside of the dizzy. Make sure you have the meter preset for checking dwell/6 cyl/degrees. Wierd that it would kill the signal unless you are introducing some other current..or resistance.

donk · 06-28-2004, 07:33 AM

I can't help you with the Autoranger... Sounds like your doing it right to me. For my car, I connect one lead to the dist wire (the same one you're talking about) and the other to the ground on the coil bracket nut. So I would guess you need more specific directions for the tester you're using. Sorry, not much help.

alan911 · 06-28-2004, 07:37 AM

THis is for the Permatune. No flames please.

"To avoid damage to the unit and voiding your warranty: Do not attach a dwell meter to the coil. Do not connect 12 volts to the coil. Do not connect a test light or jumper wire to the coil, distributor or ignition box, use a Volt meter."

Why would you want to check the dwell on a CDS unit ? Just curious.

TSwede · 06-28-2004, 08:33 AM

They are not points in their truest sense but are points used as a trigger for the CDS unit.. they are as susceptable (if not moreso than standard points at higher voltage) to running differences if not set right.. also there is a school of thought that the gap represents the accuracy of the dwell setting less and less as the distributor gets more worn/older - though I know nothing of this..

TSwede · 06-28-2004, 08:34 AM

...that the meter is faulty - it is quite old.. It reads voltage OK though so can't be completely fried...

alan911 · 06-28-2004, 08:47 AM

But it doesn't explain why you engine started to run crummy other than you may have shorted the circuitry temporarily. Hopefully.

alan911 · 06-28-2004, 08:56 AM

Again from Permatune"

"The Perma-Tune system uses the points only as a sensor so they will generally last the life of the engine."

"Dwell is not a factor simply set the points to stock gap specifications and then adjust the engine timing using a timing light."

Now, I'm really confused.

TSwede · 06-28-2004, 11:13 AM

Done it - my meter connects differently to the ones folk refer to on the boards.. + to battery, - to battery and the third blue wire to the dist.. Got to points to 36 degrees - just within spec... but what a fiddly &*^&% of a job.. I'm never going to do it again.. I'm going down the Pertronix road....

Points!! Ha.... You shall trouble me no more...