hows it going H/T i keep having a issue breaking the key on cam gears and chewing up the tip of the cam shaft on my rebuilt z6. the z6 is a factory rebuilt z6. it does have a 89 crx crank pulley, not sure if that could be an issue, it had a one piece aluminum crank pulley before. if anyone has had this issue before feel free to chime in, all and any tips or advice will be appreciated.

 

sounds like you're using garbage cam gears.

 

Cam gears are Oem.

 

to do that with a steel oem gear, something needs to be seizing up the cam really bad. either the valve lengths are terribly wrong and maxing out before it hits peak lift, or you mixed up the cam caps or are using cam caps from a different head.
cam caps are crucial to be original from that head AND placed in the correct locations, and torqued to proper spec.

 

The head, cam and cam gear were all new, this happend to my first z6 head coming from San Diego, it was running great 2 day ago with no problems. I've never had this problem before with other motors I've built.

 

Its gone....

 

What's gone Tony_2018?

 

So I was told the cam gear key break due to the cam gear bolt not being tight enough allowing it to walk out but I don't see how when the bolt was torqued to the specified foot pound it says in the manual?

 

Did you use the original cam gear key? Is it the original key? For it to break off and caused that much damage to that area is insane.

 

Yes all original

 

The key should be part of the cam gear. Tony might be right, maybe the valve tappet adjustment is too tight and the valves at putting a lot of pressure on the camshaft?

Are there any other modifications on the engine other than the crank pulley?

Is your wrench calibrated correctly? Get it checked or if it's a cheap torque wrench throw it in the trash.

 

I took a nap and thought about this. If the timing belt is too tight it would cause the cam to rub against the head and grind against it harder than it should, right?

Do you guys think the timing belt being too tight might cause this?

 

Hondur - the key is part of the cam gear, valve lash is set to intake-8 exhaust-10. No other mods. All stock. Went to the junkyard and got another cam and bought a new T-belt tensioner. Gonna re-lash the valves tonite and run it at 2500rpm tomorrow for a while and see what happens.

 

overtensioned belts make noise. a belt this overtensioned would wail.

 

I'm as stumped as you guys. When the cam gear broke the first time there was scoring on the cam journals both head n cam, n this time there was a very light scoring othe 3rd n 4th journal on the head.

 

Shot in the dark: Cam gear on backwards?

 

No cam only fits one way cause of the distributor key

 

 

The question is why did it break. Were the cam holders not lubed before installation? There seems to be some scar's from the camholders.