Alex Sol

Fellas,

I started a post in the 964 forum on the rebuild of my 1991 964 C2 with 292,000kms in November. It's been quite a journey and pretty close to the finish. Just one minor situation....

My mechanic (and I) set the Cam timing a little off and cause some major stalling issues and backfire. It ran fine for two drives around the block and then we could not get it started again. He has rebuilt 6 or 7 911 motors and was a full time BMW wrench for 20 + years....


When we went to investigate, we opened the Rocker arm cover and found 3 broken Rocker Arms!!! Anyway, hopefully we have not any irreparable damage and can replace the 3 rocker arms.

If anyone out there that has these that just happen to be collecting dust, i would be happy to take them off your hands (for a reasonable price of course!).

The are on the exhaust valve side and all 3 broke in half. would anyone have any experience with this and would you suspect there to be any damage to the exhaust valve perhaps making impact with the piston head???

Thanks for your help!

theiceman

Alex Steve Weiner and Pete Zimmerman on the 911 forum are engine rebulders and P car shop owners and coud comment. personaly I think your valves are toast , and would at least have to check.

Imo000

Broke 3 rocker arms???? WOW. How the hell did that happen? it takes a considerable amount of force to snapp it.
Why was the engine even started when the cam tining was off? Did you guys know it was off?

Alex Sol

thanks for the comments fellows. we advanced the timing 4 degrees when it should have been 2 degrees. i think. you are right that it would take some serious pop to snap the rocker arms. it was running incredibly smooth and stalled after about 30 mins of running then we brought it back to the shop. I turned over the motor a few times and pow! the motor backfired and a small explosive sound was heard....

Alex Sol

Okay, i picked up 3 used rocker arms from Frank at nineapart and will install Tuesday. I asked him to pull the exhaust valves too as they would like be bent / mangled beyond all recognition/??

theiceman

i woild imaine they are bent. i think a leakdown would tell you instantly without pulling the heads off would it not ? I can't imagine they are not bent if there was enough whack to snap a rocker arm.

back to stock cam timimg ?

Alex Sol

thanks ice. back to stock timing alright....

looks like i am missing a small 'key' that is stopping the cam from rotating when manually cranking the motor.