KIWI Mk2
I/C ENGINE BUILD
Part 5 By Vince Cutajar
KIWI Mk2
I/C ENGINE BUILD
Part 5 By Vince Cutajar
The next operations on the rear part of the crankcase is where I decided to deviate from the instructions in the article. I skimmed the side where the timing cover sits. And then I stopped to meditate on the next steps.
I then took a piece of 10mm silver steel and turned one end 45 deg to make a temporary punch. Put the punch through the front half which was a nice fit, and marked the rear side on the bearing housing. The the plan was to put it on the rotary table for facing and creating the recess for the front half spigot, but could not find a suitable way of clamping it properly. So after much fussing about it was time to try the 4 jaw chuck on the lathe.
Unfortunately, the piece of the casting I wanted to chuck has a slight taper, so pieces of marine three-ply wood were inserted between the jaws and casting so that it could grip the casting better and also avoid scoring the casting with the jaws. Eventually the casting was lined up with the punch mark I had done earlier and the face was trimmed off to dimension. Then the recess was machined and a trial fit was attempted with success. Nice fit without any slop.
Next operation was supposed to drill and tap for the 6 bolts which will hold the crankcase together but am having second thoughts. On the plan it specifies 4BA which I was going to replace with 4mm ( which I already have ) but I suspect that would be cutting it too tight for the bosses (especially one of them). So I was thinking of using 3mm bolts instead.
I am a bit hesitant in describing it, but it did work, so here goes. I chucked the timing cover in the 3 jaw chuck and using a pointed tool in the tailstock, lightly marked the centre. I put the cover on the casting, centring it by eye, and taped it up with masking tape. Put the casting (with taped up cover) on the rotary table and centred it using the centre mark I had on the cover. Clamped it tight, removed the tape and the cover and machined it. I must have been lucky because it worked well.
Timing cover is now attached to the casting. I also faced off the bosses on the front crankcase casting in preparation to drilling.