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1st 930 Valve Adjustment Mystery

Hello,

Appreciate assistance to the following. I have done valve adjustments on my previous P-car (1980 911SC) w/ no issues. The procedure for a 930 should be fairly similar, just a few more items to remove. So the mystery is this, I align the Z1 mark to the crankcase and observe where the rotor is pointing. I assume it should be on the cylinder #1 mark of the dizzy. Instead it's before!
Any thoughts?

Thanks
Old 06-22-2014, 05:18 AM
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Try rotating the pulley one more full rotation and get Z1 back at the top. You may be at TDC on the exhaust stroke.

Rahl
Old 06-22-2014, 08:26 AM
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Your timing is advanced. That's just spark, your cam will be properly aligned to adjust #1 cylinder valves.
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Old 06-22-2014, 08:34 AM
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The rotor in my car doesn't point directly at that factory hash mark either and neither does the one in my old BMW when #one is at TDC on the compression stroke.

In a 4 cycle motor the cams and distributor rotate half the speed of the crank so turning your crank one full rotation 360* will turn the rotor one half turn 180* and it will point approximately opposite the hash mark.
Old 06-22-2014, 08:47 AM
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Quote:
Originally Posted by frankie11 View Post
Hello,

Appreciate assistance to the following. I have done valve adjustments on my previous P-car (1980 911SC) w/ no issues. The procedure for a 930 should be fairly similar, just a few more items to remove. So the mystery is this, I align the Z1 mark to the crankcase and observe where the rotor is pointing. I assume it should be on the cylinder #1 mark of the dizzy. Instead it's before!
Any thoughts?

Thanks
As you turn the crank in the direction of rotation, watch the #1 intake valve open, and then close. You are now on the compression stroke for #1. Continue turning the crank in the direction of rotation, as Z1 should be about to align with the mark. You are now at TDC number 1. The rotor "is" where it is. Probably in the general area, but watching the intake valve assures relative position.
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Old 06-22-2014, 09:02 AM
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To add to this the TDC mark on the 911 fan housing that you use to align the Z1 mark on the pulley is not accurate but the split case seam under it is. Unfortunately the fan housing covers up the case seam when it's installed.

If you align the pulley Z1 mark with the case seam while timing the cams and then install the fan housing you'll see that the fan housing mark is a little off.
Maybe not all of them are but the one on my '87 is and so is a friends '87 and we both have factory Porsche magnesium fan housings.
Old 06-22-2014, 09:40 AM
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+1 what Jim said. The TDC mark on the fan housing can be off by a few degrees. The best bet is to find out where true TDC is. And it is quite simple with a piston stop. You can make one with an old spark plug. True TDC is a must for any type of valve/timing work.
Old 06-22-2014, 11:00 AM
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dont worry, just use the mark on the fan. the dist is only to get you on the compression stroke for #1. i dont use the dist for this. cap is a pain to get back on. just watch for #1 intake to close the line Z1 up when it comes around again.

if the mark on the fan is not right that could be bad for the motor since you use that to set ignition timing.
never heard of this being the case.
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Old 06-23-2014, 03:47 AM
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