First I would like to say hello to everyone. I have used these forums for some time now and they have been extremely helpful in working on my 911sc for a couple years. Since this is my first post I am including a photo of the car so I won’t get commit that social mistake.
Here is my problem. Recently I was racing my 78 911sc at a Daytona SCCA race and when I returned for tech. inspection after the race it was idling rough. It felt like it was missing on a couple cylinders. On acceleration and wot it runs great. Track times were right on the money with previous runs at Daytona. To my knowledge there were no over revs and it was running up to it's normal 6400 rpms in fifth gear on the track.
I brought the car home and started the normal checks. Spark plugs, spark plug wires, Dist. cap and rotor. Vacuum leaks, air box cracks, and all tested fine. Now it was time to break out the compression tester. These numbers were performed cold (for the sake of the neighbors).
Left side #1-145,# 2-135,# 3-140, right side # 4-45, #5-40,# 6-55. There is no smoke being produced by the engine when running.
When I found the first low #’s on #4 I thought to myself burnt or bent valve, but all three at the same time with similar compression #’s.
I was wondering if it is possible my cam timing on the right side may have jumped a tooth, or is it possible for the cam timing itself to move?
Any help would be appreciated.
