I had a close call with my engine last Friday!! Since the cam and rocker change the engine only had about 30 actual miles on it not counting garage idle and run time.
The weather was nice Friday so I went home a little early to take advantage and drive the Cobra! I had it out of the garage when I fired it up and noticed that it was not running right. It had a dead miss! I broke out the water spray bottle and found that the number 7 cylinder was not firing! The header was cool. Shut the engine off and checked plug wire but nothing seemed out of place. Started it again, still missing, so I revved it a little and heard a clunk sound from the drivers side valve cover!! That did not sound good!!
Shut it down, pushed it back into the garage and started the process of taking off the driver side valve cover! When I lifted the valve cover away from the head a roller rocker fell out and down to the garage floor!! My first thought was, “Oh great I have broken my engine without even zinging it!” Second thought was where is the nut that holds the rocker arm on? I found the nut lying at the bottom of the head rail where the
oil collects to drain back into the engine. The allen head lock nut was still inside the nut so nothing went down into the engine!! (Huge Sigh of Relief)
My guess is that I had not “locked” that nut tight enough and with the engine running had backed itself off until it finally fell off and that is the clunk that I heard. (It only ran for about 10 seconds after I heard the noise!) LUCKY ME!! It was an intake rocker arm so the engine was not getting any air/fuel into that cylinder, hence the cool header.
The roller rocker was fine, the pushrod was fine and the locknut was fine. It just flat fell off!!
I reinstalled everything, checked lifer preload and turned the engine without the coil wire and all looked good. Inserted the coil wire and it fired right up and ran fine.
I checked the other nuts on that side and all were tight! I then drove it about 6 miles and after cooling I rechecked all 16 nuts again!! I drove it about 30 miles on Saturday before the weather got ugly and all seems to be well!!
I was LUCKY!!