Timing Question ('82 911SC)

[cdagnolo]

Ok guys, I've read enough to realize that setting the timing on my car is not far from black magic. Here's the deal; to begin with, it's pretty much a stock 3.0 but has MSD ignition (no adjustable or digital timing lights!). I've got the perfect old school inductive timing light and gave it a whirl the other night.

I plugged the 2 vacuum lines, did a minor tweak of the distributor to get her to 5 btdc at idle. Then, when I revved her up to check the advanced mark, I don't even see the 25 btdc mark. I really didn't want to start turning the distributor drastically so. I stopped. I was wondering if the vacuum advance was non-working (ya, I've since read that isn't likely to have anything to do with it.)

Full disclosure, I don't know what revs I revved it to but, in reading threads, some say 4000, some say 6000rpms. Seems that the timing is advanced as far as it's going to go, anywhere up in that area. I'm thinking I was up between 4 and 6k.

For one thing, an assistant would be hugely helpful. I CAN get one of those occasionally ;-) I probably need to do that.

I did, by the way, check if the vacuum advance is working and I believe it is.

What am I missing?
HELP!
cd

[Flat6pac]

You need to make sure your advance and retard vacuum is hooked up correctly.
The retard is pointing back to the distributor. At idle your hose for the retard will be sucking air..put it on your tongue and you ll feel it sucking.
The vacuum advance, connects to the outside of the pod, hose is above the butterfly so you need air going into the engine fast to vacuum the advance.
You have a PM.
Bruce

[Josh D]

Also, there is no 25* mark. You need a timing light that is adjustable. You would set the knob on the timing light @ 25*, rev until it is no longer advancing, and see where your Z1 is in relation to TDC.

[cdagnolo]

I believe there IS a 25 degree mark (see attached diagram). I see the additional mark when the pulley is stationary and I've marked it.

Also, as I mentioned originally, the mfr of the MSD ignition system on the car says 'do not use digital and / or adjustable timing lights on their system'. They say it's 'possible' to get a correct reading but, you can't count on it so, they say, don't use them.

Weird, I know. I wish I had the link to the tech's comment on their site.

Thanks,
cd