tristessa wrote:Amskeptic wrote:We shall continue nonetheless . . . "no indication of a problem" save for a valve adjusting screw that was desperately disappearing down the rocker arm trying to find the valve stem.
You're overstating things -- yes, the screw was gradually adjusted farther and farther into the rocker arm, but it didn't suddenly start happening. Having to occasionally adjust the screw inwards because the 3000-mile valve adjustment found a couple of valves at 0.007 instead of the coulda-swore-I-set-it-at-0.006 isn't something I found particularly worrisome. If I'd kept a detailed log of every single valve adjustment, I probably would have noticed earlier, but I don't tend to be that anal .. er, "meticulous."
I read valve adjusting screws like tea leaves now. Without benefit of personal experience with a given engine or maintenance logs, the appearance of the adjustment screw would have . to . have . been . way into the rocker arm with the entire bottom of the lifter rubbed off, no?
I am currently looking at the BobD exhaust rocker arms, two of them have about one additional thread sticking out in comparison to the intakes.
Boxcar, a valve seat seat recession problem is readily identifiable by looking at the threads sticking out above the lock nuts. If one or two valves have noticeably more threads sticking out than the others, that would be evidence of recession. If the lifters have gone flat/been ground down into a facsimile of a pipe, then you would see that adjustment screw way down flush with the lock nut.
I have seen engines where the entire bank of rockers had screws jutting out and the other side of the engine had screws that were all in deep . . . that is more like engine build issues, like a flycut on one side of the engine is different than the other.
In the Hall of Infamy, I have seen some engines with different cylinders and pistons on one side than the other, several heads that were totally different, a couple with sealing rings on one side of the engine but not the other, and Herrnkind's engine had 9/14mm valve adjustment screws on one side and 8/13mm on the other. This can change the appearance of the screws and nuts in a hurry.
It is when you have an individual screw that is totally different than all of its friends, that you are very likely looking at the above issues.
Colin
(we could have fixed that engine tristessa! if the lifter would have just been able to leave its bore . . . )
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles