timming jumping around?

mopar340dave said

The oil pump/distributor drive shaft runs through and sits on a hat bushing that is pressed into the block. If that bushing is worn it will allow the distributor drive shaft gear too much room to move around and it will destroy the cam and drive gear....and who knows what else!

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I had the same problem on my 360 I rebuilt 3 yrs. ago and didn't replace this bushing Dave's referring too. Made it real hard to set the timing right on cause it jumped back and forth 2-3 degrees constantly. I had to take it back apart to replace a defective oil pump and replaced the bushing and now the timing is rock solid.