just replaced the timing chain in my 68 galaxie 500 390. when i pulled the old top gear it was missing the nylon on 10 teeth! anyways.....i replaced the stock chain and gear with a double roller setup. when i started it up i was getting a horrible metal on metal noise. tore it back down , and discovered the chain and the eccentric were hitting the casting marks on the inside of the cover. reinstalled and now i get a chatter out of the cover at idle. methinks the eccentric rubbing. when i give it gas it stops. tear it down again or let it "wear in"?