2.3L Throws Off #4 Exhaust Cam Follower

[Dtruedog]

This is a 1089 L4 Cobra setup. Tuned timing to ~9 deg BTDC at 650 rpm in gear. Briefly ran motor to 3000rpm. Backfired, then engine backfired every power stroke. Pulled rocker cover and found cam follower laying on head. Hydraulic positioner seemed ok.
What would cause this? Reinstalled follower, cover and fired it up. Damned if it didn't come off again at around 3K rpm.
Can anyone tell me what exactly to look for to troubleshoot/repair this. Totally annoying since Summer is almost gone!!

 

[Speak]

Re: 2.3L Throws Off #4 Exhaust Cam Follower

When the follower falls off has the valve returned to the closed position? If it has not then that's your problem. Try compress the valve with a set of big channel locks with the follower off to see how the valve feels. Which valve is it. Intake or exhaust?

 

[Dtruedog]

Re: 2.3L Throws Off #4 Exhaust Cam Follower

I believe it is the exhaust valve, #4 (second from rear of head). The valve seems to be free and move readily. I think it's closed as the pressure/contact between valve stem and follower is tight when I release tension on the valve spring. Didn't use a gauge but valve tension seems pretty strong, similar to the other valves. No visible damage to the follower or retainers. Repositioned follower and I compressed the valve and it went right back in place. Compressed valve to check and turned crank several times watching the valves. Everything looks ok!

Is it possible the cam lobe has a slope in the grind, other than level, front to rear or converse, that would act to wedge the follower off to one side and fail?