So, next step is partially assembling to check for rod bolt clearance in the crankcase. I expected maybe a little interference, requiring some slight grinding for clearance, because of the long stroke. This is a shot of the assembly. There is a piston on the left rod to guide the rod appropriately. I'll eventually do the same with the left side crankcase half, with a piston on the right side rod.
The problem is worse than I expected, with significant interference. You can see the bolt head hitting the case in this picture.
This shot shows the area (between the marks) at the front of the case that needs metal removed to clear the rods. There's a similar area at the rear.
I hadn't expected this much problem, but after looking at it, I realize part of the problem was the rods I was using. Instead of Carrillos, I'm using a set of Don's (madass) rods, which are pretty much copies of the Carrillos, and very nicely done. Unfortunately, they have 3/8" bolts, instead of the 5/16" bolts Carrillo uses, so the heads are larger diameter, and also a little further out from the center-line. Both rods use ARP 2000 bolts, but Don chose to go up one size. Great for strength, but not so hot for clearance. They might work fine with stock or short stroke, but with the 93 mm stroke, there just isn't room for them.
I'm still working on a solution. One option is to order a set of Carrillos, and hope they have them on the shelf. I'll check with them and see. I don't want to have to wait till they do another batch of Norton rods, because I need to get this project done in time for the rally in July. I might still have to grind some clearance, but it would be a lot less. Another option is to tape up the crank, and grind the heads of the bolts at 45 degrees for clearance. I've actually done that before in a race Commando, and it worked fine. Even then I might have to grind the case a bit for clearance. The problem is that every time you tear it down, you have to use something like vise grips to remove the bolts, and you have to put in a set of new bolts, and then grind them to fit. I'm hoping to not have to tear this engine down for a long time, but you never know. Using stock rods is also an option, but I've already balanced the crank for steel rods, and don't really want to go through that again. Besides, it is 1006 ccs, with cam and big valves, etc., so that might be a bit much for the stock rods.
Stay tuned to this station for further developments.
Ken