I'm a newbie to this forum and a Volvo rookie. I just picked up a 87 760 Turbo Sedan by chance with 60K original documented miles. As I was messing around under the hood checking things out, I loosened the bolts that hold the distributor on instead of the cap and ended up twisting the distributor. I haven't removed the distibutor but what do I need to do to ensure I haven't altered the timing or something? Can I just put the bolts back on and retighten or is there some adjustment to be made? Any help/advice would be appreciated.

Thanks for the info. I'll see about getting hold of a timing light. Now I'm confused a bit after reading about the ignition timing in the Haynes manual. It says checking and adjustment of the EZK systems timing is not a routine operation. I'll probably show my ignorance here but, why did Volvo allow the distributor to alter timing?

Ignorance is not a problem here. In fact, without ignorance there would be no reason for this board to exist.

Adjustable distributors were the norm for many years. The timing of the spark is important to the proper combustion of the fuel. In fact it is not a constant value. The ignition timing varies with engine rpm and load. In the past, this was done with weights and vacuum mechanisms. Today it is more common for the engine control unit to make the neccessary ignition timing changes. The timing in your 87 is controlled and varied by the computer, the 12 degree before top center (BTC) is the base setting for the timing. This means that at idle, the spark occurs 12 (of 360) degrees of rotation before the piston reaches the top most position in the cylinder. As the rpm goes up it is necessary for the spark to gnite the fuel sooner. This is called spark advance. If the spark is too far advanced, the engine will ping or knock. There is a knock sensor on the side of the engine to detect this, and if it occurs, the timing will be adjusted back closer to TDC, or retarded.

Hope this helps.

Dan

As the distributor fits into the camshaft, manufacturing tolerances might allow timing to vary slightly at the factory. All you are doing is setting the initial timing of 12º BTDC one time. The B230 series of engine with the cam driven distributor are very stable with respect to timing. Once the timing is set, it will be many years before it might be changed. Yes, it should be checked periodically, but don't expect any wear in the distributor drive to let the base timing change.
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john

Rotating the distributor does change the ignition timing. It needs to be set up with a timing light. Takes about 2 mintes if you have the light. Spec is 12 degrees BTC.
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David Hunter

Thanks much for the info by all. I look forward further interaction and learning on this forum...maybe even a few contributions to help others as well.