930 Distributor rotor position

totle · totle's Garage

After changing the seal, I am not 100% sure that I got the distributor back in the same position as before.
I am looking for any mark, but the only mark I find on the distributor is facing towards cyl #1.
I am quite sure it is placed almost like before.
I have set the crank to TDC for Cyl #1 and below is what the position looks llike.

Can anyone tell if this is the correct position, or where I can find the mark for the position?

The car is a 78' 930

A930Rocket · 03-12-2010, 06:08 PM

Isn't the #1 cyl at the hash mark at about 11:30 on the edge if the dizzy?

Flat6pac · 03-12-2010, 06:40 PM

CCW is the rotation. Leading edge of the rotor is in the correct position for #1.
Bruce

pete3799 · pete3799's Garage

Why is the notch on the dizzy not lining up with the rotor?
Looks like it's about 90 degrees off.

totle · totle's Garage

Quote:

Originally Posted by Flat6pac

CCW is the rotation. Leading edge of the rotor is in the correct position for #1.
Bruce

So you are saying this is correct position? I should be pointing towards the spark wire for cyl #1 on the distributor cap.
Kind of feel that I am a little much to the left??
Is there any mark to line up towards?

Quote:

Originally Posted by pete3799

Why is the notch on the dizzy not lining up with the rotor?
Looks like it's about 90 degrees off.

If you look at the position for the spark wires on the distribution cap, you will see that it points towards cyl 1
Im am not sure if it is 100% lined up

911st · 03-13-2010, 08:10 AM

Remember the crank has to turn over two full times to fire every cylinder.

Thus, you have a 50/50 chance you are at the right place to time the dist when set at TDC.

You have to be at TDC and have the crank phased to be at the end or top of its compression cycle.

You could pull all spark plugs except #1 and turn motor until you hit a compression stroke or just take #1 out and turn until you sense it is skipping a compression cycle and turn all the way to TDC.

On some cars the rotor will not be perfectly lined up. If so I would set it to the advanced side (hits hash mark before TDC or just after the mark).

Flat6pac · 03-15-2010, 08:25 AM

#1 wire is suposed to be to the left of the clip and #5 to the right of the high clip.
Bruce

Flat6pac · 03-15-2010, 08:27 AM

Is that a 76/77? then it turns clockwise but #1 is still to the left of the clip.

totle · totle's Garage

The illustrating picture is taken from waynes book. Does not know which direction this distributer is for.

First picture is from my 78 930, and I think this turns counter-clockwise

Flat6pac · 03-15-2010, 04:13 PM

Yes it does and it is correct for #1
Bruce

totle · totle's Garage

Thanks Bruce

equality72521 · 03-19-2010, 07:01 AM

Bringing this back for a new question. I thought I knew how the CDI/dizzy worked but not so sure now. Exactly what triggers the CDI to fire at the correct moment? The CDI discharges through the green wire to the coil inside the dizzy. Then through induction the charge is passed to the rotor and then to the spark plug wire. But what tells the CDI to discharge in the first place? Is it being triggered off RPM?

jwasbury · 03-19-2010, 08:31 AM

Quote:

Originally Posted by equality72521

The CDI discharges through the green wire to the coil inside the dizzy.

I thought that the green wire is the signal from the dizzy to trigger the CDI...but I don't really know

fredmeister · fredmeister's Garage

Not quite right.
The green wire is a coaxial cable that sends a trigger signal back to the CDI box. The CDI box sends high voltage to the coil which steps it up again and sends this higher voltage to the distributor thru the center cap wire.
The cap has 6 posts (1 for each plug wire) that have a copper or aluminum contact internally that gets connected as the rotor turns inside since it acts like a rotating switch. As the rotor makes contact with each post that spark plug wire fires.
The signal for the green wire is generated by a little spider like assembly that has six legs inside the distributor (under the rotor) that generates a pulse signal for the CDI box to fire as it rotates.
When you set your timing you turn the distrbutor housing relative to the rotor which is fixed to the shaft and fixed in relation to the crank. You are basically making the rotor come into contact with the copper contact inside the cap either earlier or later in relation to the crank position.
I tried to simplify my explanation as much as possible to make it understandable.

equality72521 · 03-19-2010, 08:41 AM

So looking at the first picture the rotor should line up with the "spider" tooth, correct?

smurfbus · 05-17-2011, 12:33 AM

Quote:

Originally Posted by totle

After changing the seal, I am not 100% sure that I got the distributor back in the same position as before.
I am looking for any mark, but the only mark I find on the distributor is facing towards cyl #1.
I am quite sure it is placed almost like before.
I have set the crank to TDC for Cyl #1 and below is what the position looks llike.

Can anyone tell if this is the correct position, or where I can find the mark for the position?

The car is a 78' 930

Quote:

Why is the notch on the dizzy not lining up with the rotor?
Looks like it's about 90 degrees off.

I'm wondering the same thing? The notch at the distributor on totles pic is about at the 9 o'clock and the rotor points to one o'clock? Is this distributor the original 930 distributor? My 79 (should have the same distributor) points to the same direction as the rotor when at TDC for cyl 1.

I can see that you can't turn the distributor 90 degrees as then the vacuum pot would be facing where the turbo oil lines are.

So does it not matter which distributor (or distributor position) one uses if you can get the timing set?