whats up guys im mike, still pretty new to this forum though ive tried searching the topic because im not new to forums in general lool.. couldnt find enough information so here we are. first of all i have a theory as to why this happens with these engines. im talking of course about cylinder #1 going out of round at the upper section right behind the water pump.
from what i can tell every other cylinder is wearing evenly in both of these 250's ive torn apart so far.
one is a pre 75 non emissions that had been at least taken apart and freshened up at one point from what i could tell by the gasket maker and the driver side cracked head bolt hole behind water pump indicating he should have used head studs lol.
other one is a 1979 integral with a clearly longer service life with some possible neglection as well but overall not terrible for 80 dollars.
both engines seemed to show even cylinder wear on cylinders 2-6 but the same type of tapered wear focused mostly on the area directly behind the top of the water pump impeller. from what ive read people claim the number 1 cylinder runs hotter than the other 5 and im not so sure thats the case.
with even wear on every other cylinder that would indicate a consistent temperature change throught the entire cylinder allowing for evenly dispersed slow enough for safe expansion and contraction. with the water pump pumping cooled water directly onto that upper portion of the cylinder wall it causes that upper portion of the cylinder to not expand to quite the tolerances as the rest of the cylinder promoting increased friction and wear inevitably egging the cylinder out.
this is my theory and im more than ready to entertain any other ideas or findings on the matter. i dont yet have any exact measurements, i need a good, painless, and accurate bore gauge for about 50-60 dollars or less as long as its a good product! but i am concerned about this problem because on the 79 integral motor the edge created from the wear appears to be close to .030 deep and the engine appears to be completely standard. it just sucks i got that other engine that looks beautiful inside, and the block is cracked.. i just hope the 79 block is useable because though the engine may come cheap its still annoying to have to find another engine for the right price in hopes its unmolested and rebuildable.. any insight is greatly appreciated and entertained.
