I spoke to the engineering workshop today. They haven't looked at the rods yet, will need to make up a mandrell to do the measurement and asked me if I was going to reuse the bearings (if I was they would have marked them, left them in to get the benefit of their experience. I thought the last comment was quite interesting.
So with nothing happening on the rods I turned my hands to cleaning the pistons. I used diesel, brakecleaner, brass bristle brush, green scotchbrite and dry brillo pads as I didn't have any wire wool ready to hand.
Yep, I know there's only 3 in the picture, number 4 is soaking as I type this
That then led me onto thinking about the gudgeon pins. I went on an internet search, then searched on here to see what the dimensions and wear limits were, eventually ending up on the WBX Log page. Along the way there was a post that said the gudgeon pin was 24mm, though I suspect that is a nominal 24mm
http://forum.club8090.co.uk/viewtopic.p ... &p=8158242
Like Paul I couldn't find a WBX spec so widened my search, first looking at a/c CU engine then going back to original type 4. My Haynes manual for the 412, is vintage 1974, so it has lots of information in it and actually states the gudgeon pin clearance is 0.01mm to 0.04mm. In case friends across the water are looking I'm also going to say wrist pin, but you can do the conversion to thou yourself
Next I measured my gudgeon pins. As you can see in the pic mine measured 23.985mm - I did carefully calibrate the mic before measuring. The pin measures the same at the ends where it sits in the piston, so doesn't appear to be worn. (small end constantly rotating, gudgeon pin not, when in use) I zoomed in on itchyfeets pictures and his pin measured 24.005mm with the small end measuring 24.02mm giving a clearance of 0.015mm. Pretty good
I don't have my rods so cannot measure my little ends and get the clearance. From feel before removing the pistons & withdrawing pins I would say that the little end fit was good.
You should also be able to see that I have carefully filed away the little burr that was on the top of of piston 1 so that won't be a hot spot in the future