6v53N slight knock after injector replacement

"I have a 6v53 in a 29' bo

"I have a 6v53 in a 29' boat with dual exhaust. I had the injectors rebuilt by a local (Signal Hill, Ca) shop that has a very good reputation for Detroit as well as other injectors.

After installation, there is a slightly louder "diesel knock" from one cylinder. Runs fine but doesn't sound "right". Especially at low speed in gear. I set the timing and re-checked with a borrowed Snap On dial indicator.

There is also just a "wiff" of gray smoke from the port side at idle.

My question is what else in the tune up area could cause this.

Thanks, Larry"

"Your fuel rack is not set,cau

"Your fuel rack is not set,causing it to dump more fuel on that cylinder. 9 out of 10 thats it, anytime i change fuel injectors i reset the fuel rack.If thats not it, possibly could be a leaking injector. try setting the rack 1st let me know how it goes"

Thanks. I'll give it a go

Thanks. I'll give it a go next weekend.

"Thanks Mikey,

The 2L was o

"Thanks Mikey,

The 2L was over fueling. I set the rack to the best of my ability and it was better but still not quite right.

There happened to be a Detroit mechanic working on another boat that saw me with the manuals out with head scratching & stuff and came over to see what I was doing. (I think he felt sorry for me)

Anyway he jumped in and did a quick check on the rack with a screwdriver pushing on the fuel rods on the injectors and said they felt good.

He then had me start it. He backed the fuel off on that injector until it quit knocking. Then he said that either the injector wasn’t calibrated correctly at the shop or it may be a burnt valve or both.

The injector shop will give me another one no problem but what are your thoughts on the valves.

Also would there be any downside to doing a valve job on only one head.

Thanks, Larry"