16H Main Bearings again!

Gary:

Can you provide us with the bearing numbers on the bearings?

Mike

https://www.wdnorton.nl/Downloads/16h%20M&I%20manual%20200dpi%20by%20courtesy%20of.pdf

Hi Gary,

   Don't know if you have fitted your bearings yet, but I will give a brief description of the fitting order. Firstly the crankcase may be worn and the bearing outers might be loose in the aluminium. If this is the case, you will need to Loctite them in place. The first bearing you should fit is the ball type in the driveside crankcase. If the bearing is a tight fit as it should be you will need to heat the crankcase in a domestic oven at about 100 to 150 c. and make sure it is fully home by using a suitably sized drift. Next fit the loose bearing spacer and then the roller bearing outer making sure the lipped side is innermost and again tapping home. Make sure you keep the inner bearing that matches it's outer together as these should be a matched fit. Next fit the other roller outer in the timing side crankcase following the same procedure. Now you have to set the crank end-float by fitting the inners on the shafts and measuring how much the crankshaft moves from one side to the other when the cases are bolted together. There may be tightness in the ball bearing centre so you will probably need to tap each end of the crankshaft with a rubber hammer to check it is at each extreme. You should be looking for 10 thou of movement and hopefully you will have shims from the original set-up to achieve it. Any shims should be between the flywheel and roller inner as it is the outer lipped edge that controls the end-float, and the shims should be on the side which makes the little end of the con-rod central in the crankcase mouth. This might take a couple of goes to get it right. Finally you need to Loctite each roller inner to it's respective shaft and hold them tight against each flywheel while it sets.

Steel main bearing outers are not held in to alloy cases by loctite for very long, the alloy expands faster than the steel and the repeating heat cycles of a petrol engine break down the loctitie's grip. I tried it twice and it never lasted beyond 2000 miles. Much easier to have the outside of the bearing copper plated to give back the interference fit. Loctite does work on steel to steel gaps.

I have a 1928 16H, which has only two main bearings. According to the Parts list, that should be one roller and one ball race (Timing side). Imagine my surprise when stripping the engine recently, I find a roller race on both sides!

Has anyone else had the same? If so, have you left it or reverted back to the ball and roller? I must add, the engine has been running perfectly well with this setup (it covered over 500 miles in 2020)