help with ignition timing procedure ..

[ertech]

Hi guys .
done this a million times but have a brain lapse.
car is a 89 930.
if I want to set the timing at 4000 rpm,I clam the 2 vacuum lines going to the pod.
here is where I am confused .
Is this correct?I set the dial in the back of my light to 26 then point the light at the crank and turn the distributor until I see Z1 mark align with the fan?
thanks

[356911930]

Typically the vacuum lines are disconnected for the 4,000rpm timing setting. I believe your timing light procedure is correct, although I do not have an adjustable timing light myself. Your pully should have an mark at the 26 or 30 degree advanced position which you could also use if you set your timing light to zero.

You can also set the timing to … on my 1976 turbo it is 5degrees atdc at idle with vacuum lines connected. Then use the 26 degree, 4,000rpm setting as a check.

Hope this helps

Rahl

[ertech]

disconnected and plugged ?can I just use 2 vice grips to pinch?
thanks

[356911930]

The Porsche workshop manual does not say anything about plugging, just disconnecting. I suppose you could use vice grips but I am always afraid that I will crack or damage the hose. The hoses should pull off and push back on fairly easily.

Best of luck

Rahl

[ertech]

if we disconnect won't there be a vacuum leak from the throttle body?

[356911930]

Yikes, you are really testing my knowledge base! I don’t believe there is any vacuum above 3,000 rpm or there about. So it should not affect the running of the engine. On the later turbos the second “vacuum” line puts out positive pressure from the turbo to retard timing, you probably do not want to remove that one. I’m notan expert on the later turbos since I have a 1976 930. I just time the engine to the 4,000rpm mark and let the idle timing fall where it may, unless I’m going in for a smog check, since they check to see if it matches there chart. I always go back and check the idle timing because it should fall within the factory setting.

Best of luck

Rahl

[mark houghton]

Originally Posted by 356911930

Yikes, you are really testing my knowledge base!

I hear you! Been awhile since I've noodled down deeply into timing. Seems we have a pretty good stash of timing info up in the sticky