Squeaking fuel Injection Pump

I recently purchased a 1970 911S in relatively good, non restored condition. I noticed soon after I bought it that upon first starting, the engine produced a slight, intermittent squeaking noise. It would go away fairly quickly, usually after driving about a half block so I didn't worry too much. I did a leak down test and got 7%, 5%,8%,4%,4%,& 7% on 1 - 6 respectively which I thought was acceptable. I pulled the engine (will explain in background below) and while doing routine maintenance and checks, I noticed that the fuel injection pump timing was off by about 40 degrees (counter clockwise while looking directly at the cogged pulley). I removed the belt and rotated the cogged pulley by hand and lo and behold, there was the squeak. I removed the rubber cap that covers the access to the plunger and checked the plunger. It returns when depressed but does not "snap" back. I depressed the plunger and rotated the cogged pulley and the squeak goes away only to return when the plunger is released. Does anyone have any idea what is making the squeak and if is going to be detrimental to run the engine in this condition? Also, what will be the effect on fuel mixture by rotating the FI pump Pulley 40 degrees clockwise?

Thanks,
JB

I assume you 'timed' the pump back to the 'correct' FE point, right? Don't know what is causing the squeak, although the cogged belt can generate 'noise' when worn and cracked. BTW, the belt can be changed and 'timed' with engine in place, should you decide to install a new belt!

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Warren Hall
1973 911S Targa

I can reproduce the squeek by turning the FI pump pulley with the belt off. And yes I have correctly timed the pump to the FE mark on the crank pulley. I recently tuned this engine on a chassis dyno and had to enrich the pump setting to get maximum power (154HP at 7000RPM at the rear wheels) Assuming the squeeking noise is not detrimental (since it goes away so quickly) what will the effect on fuel mixture be by rotating the pump pulley to the correct position (40 degrees clockwise from where it was)?

JB

I assume that having the 'previous' mis-timing you found might affect the atomization and proper mixing of the incoming air and spray out the injector, since whether early or late with respect to 'perfect' FE timing, the velocity or flow volume would not be as great, but I seriously doubt if there was a serious problem, since the early Bosch D-Jetronic system intentionally ( for economy of circuitry) fired half of the injectors at the 'wrong time' --- even on Mercedes 450 V-8 engines, so the timing can't be 'too' critical!!!

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Warren Hall
1973 911S Targa