Why did my rockers break? 6 cylinder Options

[David Stowers]

Hi all,
All 3 exhaust rockers broke on one side (4,5,6) when I started my engine for the first rime after cam and rocker re grind.
What’s the likely cause here folks?
Thank you

[Superhawk996]

Lots of possibilities. None of them good.

I'll start with the obvious. Did the engine rotate freely when assembled? Did you verify proper valve lift?

Then to the less obvious.

Did you verify that valve springs aren't going into coil bind with the new and/or reground cam? Did you verify rocker shaft OD to rocker ID is proper? Did you verify that the 4,5,6, cam is timed properly prior to firing the engine?

Sort of odd that all 3 are on the same bank. Seems to suggest cam timing to me. (IMG:style_emoticons/default/confused24.gif)

Did you verify proper piston to valve clearance?

I'll stop there and suggest that it doesn't really matter what anyone (including myself) speculates. Only sensible thing to do is to remove motor, tear down at least that bank and get to root cause.

[David Stowers]

Lots of possibilities. None of them good.

I'll start with the obvious. Did the engine rotate freely when assembled?

Then to the less obvious.

Did you verify that valve springs aren't going into coil bind with the new cam?

Sort of odd that all 3 are on the same bank.

Did you verify proper piston to valve clearance?

I'll stop there and suggest that it doesn't really matter what anyone (including myself) speculates. Only sensible thing to do is to remove motor, tear down at least that bank.

Rotated freely, cam only changed from T to E profile. valves pistons etc undisturbed