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-   -   Sanity Check - TDC and distributor rotor (http://forums.pelicanparts.com/911-engine-rebuilding-forum/762788-sanity-check-tdc-distributor-rotor.html)

Green993 07-25-2013 11:29 AM

Sanity Check - TDC and distributor rotor
 
993

Installed distributor and have rotor pointing at the notch. Intake rocker installed on cylinder #1. Cam Timing stage completed.

Just want to confirm I am not 180 degrees out. As the TDC pulley notch approaches the crankcase seam the number one intake valve starts opening. I rotate the pulley 360 degrees and the cam is not acting on the intake rocker (it is at rest). At TDC #1 should the valves be completely closed?

Can someone confirm this is the correct combination of events. Just don't want to screw this up and I know this is a common mistake.

Thank You!

Lapkritis 07-25-2013 12:40 PM

Yes, #1 should have both valves closed at tdc. Good time to run the plug wires matching the firing order.

Green993 07-25-2013 01:19 PM

Thank You. Just want to be sure!

304065 07-25-2013 05:35 PM

Quote:

Originally Posted by Green993 (Post 7568496)
993

Installed distributor and have rotor pointing at the notch. Intake rocker installed on cylinder #1. Cam Timing stage completed.

Just want to confirm I am not 180 degrees out. As the TDC pulley notch approaches the crankcase seam the number one intake valve starts opening. I rotate the pulley 360 degrees and the cam is not acting on the intake rocker (it is at rest). At TDC #1 should the valves be completely closed?

Can someone confirm this is the correct combination of events. Just don't want to screw this up and I know this is a common mistake.

Thank You!

Hold it a moment.

You say, "as the TDC pulley notch approaches the crankcase seam the number one intake valve starts opening."

The intake valve opens before Overlap TDC, not Compression TDC. If you then rotate 360 degrees, and both valves are closed, you are at Compression TDC, at which point the rotor should be pointing at the notch in the distributor housing.

Here is a chart I made to help

http://forums.pelicanparts.com/uploa...1242665497.jpg

I think you are correct, but your first sentence confuses me. There should be no valve opening prior to Compression TDC-- at that point both rockers should have play

Green993 07-25-2013 07:58 PM

Upon re-reading that it does seem unclear. It really was an either or: Valves completely closed or approaching the notch with #1 intake opening. I went with valves completely closed.

Here's the next question: When turning the pulley do you turn it clockwise or anti-clockwise? Does it make a difference?

88911coupe 07-26-2013 02:48 PM

Facing the pulley always turn clockwise, damage can result going "backwards". I am assuming the 993 is same as my '88 Carrera.


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