Weird clicking sound?
 

Well, today I installed #0 plate, 300 marine injectors in my 12V.. Bled the fuel lines, tightened everything up, and thought I was good to go! However.. I have a problem now. I didn't notice it until after I took off up the highway - whenever I stopped at a red light.. BAM, this clicking sound appeared. I'm not sure what it really is - it's relative to engine RPM i'm almost certain of.. whenever I give it more throttle, clicking goes faster.. then on decel.. it slows back down. I haven't noticed any changes in engine temp, oil pressure / levels or anything.. and the truck definitely responds great! But this clicking bothers me.. Someone threw out the idea of KDP, but I didn't see any holes anywhere, no oil loss.. The only negative I've seen is the smell of diesel fuel whenever I turn on the heater / vents. Any ideas / thoughts appreciated!

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Update: Well, figured out what the clicking sound is... #4 is blowing out cylinder gases :(. Looks like things need to come off again.. and #3 is leaking like a mofo where the injector tubing connects... hope I didn't mess up the head pulling #4.

I had a similiar problem with my 12v. I had a clicking noise which started before I even modified it. I originally had a #5 plate in it and then the clicking got worse and it blew the headstud out of cylinder 6 and blew the head gasket. At the shop they said that the stud was cracked and that caused the clicking noise and why it got louder with acceleration because the engine was rattling it.
That could be your problem but definetly worth getting check out because the repair will set you back close to 2K

Well, not to worry.. the clicking was #4 leaking chamber gases.. wasn't sealing correctly. Got another brand new injector install kit w/ new copper seals, that did the trick! :D