This may turn into a long post but I'm at the end of my rope with this project.
Last fall I built a 59 235 for a friend of mines 52 2 door hardtop with a powerglide. He fell in love with the 62 235 I built for my 50 PU and pestered me until I agreed to build him one.
List of new parts included pistons & rings(.030 over), bearings (all standard with a nice polish on the crank), oil pump, cam and lifters, water pump, valve job and head milled .025 (just to make sure it was nice and flat), fenton headers and intake with 2 rochesters. All tolerences checked per motors manual and all fell at or near the center of the specs. Engine was broken in properly with quality breakin oil and driven only about 3 miles then went to the upholstery shop for the winter.
My buddy decided to drive it home from the upholsterer this spring and proceeded to get on the interstate and run in 70 mph for about 45 minutes steady! He overheated it (non working temp gauge, now replaced!) so badly that it melted the bearings, rods, mains and cam bearings out of it and turned the rod big ends black.
Back out and now after tuning the crank, .010 under mains and .020 under on the rods and checking all the rods for round and straight, it went back together.
Ran great for 400 miles, 40psi of oil pressure and never got over 180 degrees.
Life seemed good, until the noise came.
#2 rod bearing was knocking.
Pulled it again to find that #2 was just the first one that was going bad. The mains and cam bearings look great but the rods are all scored to varying degrees, particularly on one side of each throw.
Let me say, I have built well over 100 engines of all makes and models over the last 35 years and this one is the first that has given me this much greif. The machinist I use is 3 generation in the same location and very reputable and my buddy learned his very expensive lesson and I'm sure was not doing anything stupid this go round and I don't believe to blame for the failure.
My question for the stovebolt experts here is "why, what could have happened?"
Could the heat have changed the metalurgy of the crank or rods? The bearings seem to be correct as marked, I have had some in the past that were mis-marked but I checked these and they seem to be correct. Now I'm gunshy and thinking of finding a different crank and rods, or a different engine and start over, or even (gasp) giving him mine!
This thing is like a bad penney!
HELP!