any good ideas regarding cambelt?

[vw754]

getting my timing checked on a4 tdi (b6) awx engine 1.9 tdi PD
any pics or info on what to replace? and how it should be set? going to strip front end down and replace water pump,as i never got it done when i had a cambelt and tenioner fitted 4,000 miles ago.

 

[vw754]

rumor has it if crank timing is advanced there will be no black smoke but car would use more fuel,even though it still drives good.

what would the result be for timing thats retarded?