Can anyone here who has had the problem identify it better than a "tap tap tap...?" Does it sound like a valve tick, but less frequent? Rod knock?

Has anyone been able to look over the pistons, rods, and bore of one that's had the problem? Is it scoring due to poor oiling, or is it actually a broken ring land or something similar?

 

for the #4 cyl failures, what is the final condition of the top compression ring?

I've seen some problems where high heat and pressure will cause the ring to expand too much and pop out of the ring land. Then it will score the cyl wall, piston head starts burning and all hell breaks loose.

 

dt's old short block (#4 failure) was on display at the Irvine Mega-Meet this weekend. The #4 cylinder was badly scored (about 2" wide band of scoring running most of the cylinder length), and the #4 piston head showed a lot of burned residue. However, I didn't see any sign that a ring had failed and gotten into the combustion chamber in the manner that Silver Surfer's did. (The #4 piston was out for display but its rings were removed.)