I have a couple of questions about two components on my engine. The engine was professionally rebuilt approximately 4k miles ago so all the parts are relatively new.
First: I recently replaced the lifters with Rhoads type. I primed, installed and set the lash to one half after reaching zero. Started the engine with the valve covers off to ensure oil flow through the push rods and all checked out fine. Ran the car on and off for a week to tune the carb and always heard the same noises - a racket of lifter noise on start-up that got better as things warmed-up.
The tough part about these lifters is not knowing what is normal ticking and what is abnormal lifter noise.
After two weeks I took the car down to the local strip and made some passes to finish off the carb tuning. On the final pass I heard a valve train sound that was way-off and a notably rough idle. I connected the vacuum gage and saw the needle bouncing the the rhythm of the tick. Pulled the valve cover off and found the #4 intake push rod end-ball mashed into the rod body and the companion exhaust rocker and one inch of push rod from the ball down blued from excessive heat. All lock nuts were right where I set them as I marked them against the stud.
Question: Is this a case of a collapsed lifter? What could overheat one rocker assembly?
Second: During said test period, I noticed a random spike on my tach which coincided with an engine miss. This was totally random and sometimes occurred in clusters and others just once or twice. Im using the stock distributor with a Mallory Unlite retrofit. The coil is a Pertronics, all connections are clean and tight, all spark plugs, wires, cap & rotor replaced twice.
Question: Is this a case of spark scatter or too much vertical play in the distributor?
Thanks for any insight. The real frustration is I just got the nitrous installed and I cant pull the trigger until I get these gremlins out of my engine.
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