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Thread: Knocking sound after N1 cam install - Help

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Posts: 21-30 of 31
2011-11-16 20:20:39
If I take out the tensioner, what is the easiest way to tell that it's faulty?
2011-11-16 20:31:36
It may be cracked so the arm is just going out as far as it can holding the chain too tight.

If the arm moves, try to move it back and forth.
2011-11-17 03:18:28
UPDATE: Good news, I took out the tensioner and it moved freely, cleaned it up, filled it up with oil and re-installed it.

Now The BAD: during the sprocket install (onto N1 intake cam) there apparently there was too much tension on one side of the chain causing some misalignment of the sprocket and the cam, which caused some damage on the sprocket and a little bit on the cam. I didn't take pictures of the cam but it seems as 270 degrees of the lip is intact with only 90 degrees "worn off". I am hoping to buy a new sprocket and re-install it onto the existing cam.

Congrats 1FastP11 as you were bang on on what the issue will be, did the machine shop re-welded the cam lip and re-cut it for you?

Sprocket pics:

Last edited by Wojtekj on 2011-11-17 at 03-22-22.
2011-11-17 03:34:04
Yep, lesson learned... cast materials don't flex, they chip and are brittle. Next time slide the entire sprocket onto the came before tightening and make sure its 100% flush.
2011-11-17 03:34:35
great it wasn't something serious. u could just get a de cam sprocket as ther is no real difference.
2011-11-17 04:31:48
Originally Posted by 1FastP11
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)

Good call 1FastP11.

This thread is a good example why I alway recommend removing the tensioner when doing a cam swap. You will get a lot more slack on the chain to properly align and seat the sprockets to the camshaft. The wooden block method is quicker because you don't have to remove the tensioner ,but you will run the risk of sprocket to camshaft misalignment due to the lack of slack and movement.
2011-11-17 04:45:12
yep yep this it why i take my time an make sure everythings perfect..

them poor n1's man..

cant wait till your popped the high lobes bro you'll love it!
2011-11-17 04:56:27
In my case the sprocket got very little damage so they pinch just a little pit of MIG (I suppose) and then machined it down. The camshaft was more complex. I’m going to try to explain it but bear in mind I’m a Spanish speaker. That ring around the bolt hole on the camshaft, got machined down below the surface of the camshaft. They kind of did a negative ring, instead of rising from the surface of the cam, -it got carved down-. So now it’s no longer a ring, but a groove to fit a new ring in (cylinder). After that, they machined a brand new ring, (Cylinder with twice the height of the protruding ring), to fit (glue) onto the machined groove. Now it protrudes the correct amount for the sprocket to sit correctly. Does this make sense?
Of course I’m no expert on machining metals. But that’s what they told me they did to fix it. Anyway I think you should go to a reputable machine shop and let them propose a solution for you. If they say they cannot fix it. Take it to another one until you find a shop that’s up to the challenge.

I'm glad I could give something in return to the forum afters years and years of leechin info for myself

2011-11-17 08:44:11
You know, if it weren't for me just now seeing this thread, I would have said that the cam gears were loose.

Like, seriously, I was just about to post that as my guess.

Well, no internetz points for me tonight. I wish you hadn't have found out yet, just so I could post. How about I post anyway, and we pretend it was yesterday.

Sounds just like a cam gear not being on all the way. Sometimes they can back themselves off a bit after install if you don't torque them down really tight. Always follow torque specs.

Ok done. ^^^ called it. lol
2011-11-17 17:18:05
Well I appreciate everyone's feedback, which got the brainstorming process going, which is why belonging to this forum so valuable.

Well, the sprockets were not loose, but the intake was installed at an angle due to trapping some of the cam material and distorting the sprocket material on one side. So when the engine started the sprocket had a side to side movement inducing chain rattle which was hitting on the chain guide sides, resulting in the knocking sound.

Lynch, yes those cams seen better days, at least now I can say that they are balanced as the intake and exhaust have a similar "accidental wear" I will make sure that I squeeze every bit of performance out of them out on tracks next year.

So the most important question, who's got a single sprocket to donate to my cause????
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