Victor Adame

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.

motoxxxman

sounds like you're using garbage cam gears.

Victor Adame

Cam gears are Oem.

motoxxxman

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.

Victor Adame

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.

tony_2018

Its gone....

Victor Adame

What's gone Tony_2018?

Victor Adame

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?

tony_2018

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.

Victor Adame

Yes all original

hondur

iTrader: (1)

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.

hondur

iTrader: (1)

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?

Victor Adame

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.

eghatch9295

iTrader: (1)

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

Victor Adame

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.

Ohmega

iTrader: (1)

Shot in the dark: Cam gear on backwards?

Victor Adame

No cam only fits one way cause of the distributor key

Ohmega

iTrader: (1)

tony_2018

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.