Not out of surprises . . .
I am enjoying this project so much, I am finding ways to make it go on forever . . .
About a quarter square inch of babbitt was broken off the front edge of the front main cap, the loose pieces long gone. I was going to use it as-is, this being an overhaul, but after reading many positive statements on this forum, I checked with Bill Barlow in Bend, Oregon and he is going to provide me with a freshly re-babbitted, rough-machined cap for a very reasonable price. There will be a slight delay, but this will give me time to find more things wrong with my 85-year old-parts . . .
I am also waiting to get my freshly-installed rod bushings burnished and fitted to my new pins. The rod from Bob weighed in at exactly the same weight (both ends) as the lightest of my other three rods -- thanks again, Bob. I got all the small ends to the same weight (within 1/10 oz.) and will do the big ends later. One of the bushings did not take much force to press in, so I know that it will absolutely need burnishing if it is not to become a full-floating bushing. I would have liked to do the burnishing and fitting myself, but I have not yet found a source for a burnishing tool. Ideally, I could use a rotary roller burnisher that I could use in my turret mill, but among the many on eBay, I have not yet found one in the slightly under 1" size. While I have the rods being burnished, I am paying the shop to do the pin-fitting as well so they can make a bit of money on the job. I am also favor using a .002" oversize bushing for the one rod if the shop has a source for one. Once I have the small ends to size, I will rebore the big end babbitt, hoping to have enough wiggle-room to get all the rods the same length as one (of my original set) is shorter than the others.
Since my last post, I also did a traditional valve lapping job -- my first time for this. By luck, all the valves seat well, pretty much in the center of the generous play between the valves & split guides. The seats were getting kind of wide, so I cut them with a multi-tooth angle cutter that I had on hand. It was something like 55 degrees, but that not being critical for the job, it worked fine. I made up a simple arbor and did all cutting powered by hand. This made it much easier to control the small amount of material that needed to be removed. I also checked my two sets of springs and they came in at 40# and 50# at 2-3/8" -- I'll be using the 50# set.
Today, I laid the crank in the bock saddles and checked some things. The end thrust clearance without the caps being installed is a bit high at .009", but with the cap installed it may be closer to the .005" limit -- I still have to check that. The radial runout of the flywheel flange is .0015", thanks to a lack of care during crank grinding. The axial runout at a 2" radius is also .0015", which translates into about a .005" runout at the edge of the flywheel, right on the limit. I may do some work on that flange to cut that down a bit. It may be that the flywheel will mount better one way than the other.
With the crank laying in its saddle bearings, I found that I could rock it quite a bit, with it pivoting on the center bearing. My first thought was some amount of bend in the crank and there definitely was a position with maximum rock and 180 degrees away there was no rocking. I did a bit of straightening by using a blunt chisel and big hammer on the too-small filets on each side of the center main journal. That cut down the rocking quite a bit, but part of the rocking comes from the center main being about .002" higher (with the block up-side down) than the front and rear bearings. At this point, I have the same .004" of rocking, no matter what position the crank is rotated to. Drawing on my machine tool rebuilding hobby, I used a straight edge to check the cap-seating surfaces in the block and they are very near to being in the same plane so the block has not changed shape. Before I do anything, I need to check the cam-to-crank distance and see how much wiggle-room my new timing gears gives me. If I have enough room, the next step is to scrape the center babbitt lower and then continue with the end saddles, finishing with fitting the caps to the crank. I will probably do the block now, but wait until I get the replacement front main cap before fitting the caps.
At this point, I think that the font and rear bearings were poorly fit because of the bent crank. I pulled the crank and put the three caps on with the same shims that were in it when I took it apart -- the center bearing had around .002" clearance and the end bearings were closer to .004". Once more, I am really glad I took this "running" engine apart.
Archie
P.S.: I sense that the state this engine is in will require a very careful approach to "fix" without making things worse. I will be taking my time and appreciate any insights that anyone wants to volunteer.