Thread: Knocking sound after N1 cam install - Help

I have installed N1 cams in my ve following JWT instructions (except for using 1/4" extension to block the sprockets when torquing them down to 100 ft lbs). I also noticed when I was tightening the intake side sprocket the bolt was rotating freely and then had more resistance then was rotating freely again (until I got it torqued down), indicating that possibly the sprocket was not going on evenly. During the first startup today, I noticed a knocking sound :mad3 min after the startup), getting pretty loud which I wanted to ask on your opinions of what it might be , here is the video:

The noise seems to be louder in the front of the engine (sprocket area or chain tensioner/guide):
video-2011-11-14-20-26-02.mp4 video by wojtekj - Photobucket@@AMEPARAM@@file=http%3A%2F%2Fvid93.photobucket.com%2Falbums%2Fl56%2Fwojtekj%2Fvideo-2011-11-14-20-26-02.mp4@@AMEPARAM@@file=http%3A%2F%2Fvid93.photobucket.com%2Falbums%2Fl56%2Fwojtekj%2Fvideo-2011-11-14-20-26-02.mp4

I only idled it for 10 min after which I could not bare the noise before shutting down.

Here is the view of the sprockets before and after the install:

Before (stock cams):


After (N1s)


Let me know if you had similar issues, and the fix for this.

Thanks.

1st time installing cams? If so, you should have paid somebody to do it for you. If u took those pictures directly after the install something definatly isn't right.

double check your timing. one tooth = 20*
does it sound like your piston is hitting the cam lobe? or like a valve is slamming the piston?

One picture is before the install, the other after, what difference do you see on the one after?
There were 11 chain links between the markings on the sprockets before and after (just like in the FSM). I had the chain zip tied to the sprockets and wooden block wedged between the chain the the casting. I also did one cam at a time to prevent the chain shift on the crank.
It sounds more like a chain rattle to me but I might be wrong, it was very quiet in the first few minutes then got louder (I didn't rev it past 2k but it is more apparent at lower speeds <1000rpm).

Open up make sure everythings tightened down. U be surprised sometimes thigns u think are tightened get losse when u start up. Right lynchfourtwenty.

Welcome to -I just f*cked my cam install- This very same thing happened to me and I even was using the wood block. It's common while installing the big sprocket bolt, to bite off a piece of the cam lip (where the sprocket sits) and can be either cam depending on which one you tightened first.
The problem manifests itself when tightening the sprocket down and suddenly feel an increasing resistance (as in reaching for the final torque) but then abruptly the resistance of the bolt diminishes to hand torquing level. After that to the resistance increases allowing to apply the final 100 ft lbs. Like normal, hard, harder, loose, loose and the final hard. Don't ask me how I know. BTW this sounds pretty similar to what you described.

I suggest you to take out the sprockets again and check for damage on the cams where the sprockets sits. If the problem is there, a machine shop can fix the problem. Tightening down the sprockets it's pretty tricky, cams must be precisely at the desired locations (10&12) and with absolutely no tension on the chain.

Good luck with the problem

PS: By looking closely at the pics, I think the problem's at the intake cam (intake dowel pin looks more recessed than exhaust cam's dowel pin)

I am going to open it up tonight and see what's going on, my bet is on the intake sprocket as well as I had a "weird" feeling when I was tightening it down.
Thanks for all the suggestions.

I was thinking the dowel pin may have snapped from holding the sprocket the way you did and not using a wrench to hold the cam when tightening the bolt on the cam. If that happened then you will need to pull the cam sprockets back off at least and more than likely if you are lucky, just the cam. Your timing will also be off and hopefully it didn't damage any of the valves.

In the 1st picture the dot on the cam is lined up with the yellow marking on the chain. On the.2nd picture.the.yellow marking is completly gone....

guessed he rotated the engine after the n1 cam install, so the yellow (master) link would not fall same place, until after multiple rotations

peace