Suddenly ..... after many changes - new pushrods, new hyd. lifters, new spark plugs, new oil, new oil filter and new fuel pump ..... the distributor won't hold timing. The rotor jumps 50-60 degrees when I attempt to start it.<br />I pull the distributor and the drive gear is fine, as is the gear on the shaft. And I have been cinching the distributor to the engine very tight.<br />I pulled the plate to check the advance mechanism and cannot tell if it is stuck or jammed. Can't tell.<br />Pulled the fuel pump to see if the pumping lever is smacking the distributor drive gear. Nope.<br />Something is causing that distributor to jump out of timing??????????<br />Note: This all started with a clattering noise on the top of the engine and I've been at it for a month..... am at my wit's end.