If this question has appeared before, I apologize but I have a dilemma about my '54 GMC 350 dump/flatbed. It has its original 270 in it, which I overhauled in 2002 - rings/bearings & valves. Afterwards it had some poor compression in 5 & 6, but ran pretty well nonetheless. This summer I noticed that it was using oil and that the oil on the dipstick was creamy brown. I milled the head and replaced the head gasket, but that wasn't the problem - with the compression issue in 5 & 6, I figured I probably had either a cracked head (which was OK with the original rebuild) or a cracked block. So I clenched my teeth and kept driving it replacing oil frquently.
Last week, while hauling a load of gravel, oil pressure plummeted and fluids went to zero very quickly - engine overheated and I shut her down before anything siezed. But I think there is a cast iron problem, either block or head on this engine, and my question to you all is this: do I stay stock and rebuild the 270, knowing that it may take sleeves and a LOT of expensive machine work, or knowing that this is a working truck that hauls a lot of heavy loads, do all the fabricating of engine mounts and bellhousing to put a 350 in it? (I know, I'm on a stovebolt forum, but just listening to opinions at this point.)
I do have another 270 long block that a kind member of this forum donated to me a few years back - haven't yet torn into it to know if it works at all. I do know that this engine works at nearly the limits of its power all the time, and while I don't have to get anywhere fast, I just want to know that, if I rebuild it, I am not going to push a 50 year old casting into failure again. Appreciate your thoughts.
