Thanks tlowe. I need all the advice I can get.
I pulled the head off the motor in the jeep and found a blown head gasket. I also found .060 over pistons, in excellent condition. So while the motor looks much better inside than the "spare" there is no room for a rebore. My trusted "local", (120miles away) machine shop says maybe 6 months until they would get the spare block bored and decked. So I have a choice to make while I'm waiting. Put in a new head gasket and run it, hoping for the best, (compression was on the low side at 115- 120 prior to the head gasket blowing, the sun sheet says 130 min with 20 max variation), or do a redneck rebuild, (rings, bearings, lap the valves) and hope to get another couple years out of it. I'm wondering about decking it and surfacing the head because of the blown head gasket. That's not big money and a pretty fast turn around. I don't have any good way to check the surface flatness of either.
I set my bore gauge to 3.935, (.060 over stock) and did some measuring. Unfortunately I don't have enough experience to interpret the results. All of my prior engine rebuilding experience involved single cylinder 2 stroke motorcycle engines.
below is what I found
Cyl #1: .0030 over front to back, .0002 over side to side, both taper .0005 more open toward the top until I hit the lip which is about .0020 under the cylinder front to back and .0002 under the cylinder side to side.
Cylinder #2: .0015 over front to back, .0020 side to side, very little taper, lip is .0005 front to back and .0020 side to side
Cyl #3: .0015 front to back and .0020 side to side .0005 taper. less than lip than I can accurately measure, < .0001
Cyl #4 .0032 and cylindrical with about .0005 taper and .0040 lip
So #1 is .0028 ovaled, and #4 has some more wear than the other three, and more lip at the top. I am wondering what the expectations of accuracy on the rebore would be? And where I'd be if I just ran a ball hone through them all a couple passes and put in new rings?
