KIWI Mk2

I/C ENGINE BUILD

Part 19 By Vince Cutajar

Carved up one of the head flanges. I could have left it as is and avoid all the work but something deep down inside convinced me to do it. First, using the brass template, I marked out the head flange. Clamped the head in the vice and started milling to the marks.

The second one took less than half the time to do the first one. With all machining of the head is complete decided to do a general clean up of the head especially between the fins. These castings are coated with a light grey paint so I thought ‘how about using a paint remover?’ I tried a small area first and it seemed to be working. So using a small stiff brush I went through all the fins. After a couple of applications of the stripper the paint started coming off with the brush. Washed it under running water and gave it a good clean in the ultrasonic cleaner using water and liquid detergent. I will use this same method on the crankcase.

I was quite happy with the result. Next I will go over the head with fine sand paper to remove the machining marks.

I decided to drill and tap the four mounting holes in the top of the cylinder. I used the cylinder head holes as a template and used the usual homemade transfer punch to mark the top of the cylinder. Drilled the first blind hole 7.5mm deep and started tapping 4mm. Started with the tap in the drill chuck and turning it by hand to get it straight then continued by hand with a tap wrench so that I can feel when I reach the bottom of the hole. All of a sudden the tap felt loose in the hole and that's when I got that dreaded feeling. I must have stripped the thread.

After the shock passed I removed carefully the tap and inspecting the hole with a magnifying glass I could still see the thread. Blood started circulating again. I was using the first taper tap. So I continued tapping using the other two taps. Used a 4mm bolt in the hole and it screwed in nicely. So I guess I might have saved the hole. I continued with the other three holes without a hitch.

Used 4mm threaded rod as the studs. Cut the studs in situ with a Dremel cutting disk  so that they would be of the same height.

Started work on the rocker arm pillar using a piece of 3/8" square stock that came with the kit. Centred it in the 4 jaw chuck with a DTI  and turned and tapped one end 6mm fine.

Then with a thin parting tool I faced the shoulder by trial and error till when it was screwed tight in the cylinder head, one face was parallel to the valve guide holes. Then I marked the faces where I need to drill the hole for the rocker arm shafts and calculated how high the hole should be from the bottom of the rocker pillar. Marked where the hole should come. Used a 1-2-3 block to do this.

I then drilled and tapped the hole 3mm and just for fun fitted the rocker arm pillar to the head and the rocker arms to the pillar to see how they look. Now to make the pillar pretty and cut it to length.
Gave the column a 5 deg taper in the 4 jaw chuck. Then changed to a 3 jaw chuck. Held the pillar from the threaded end to machine the top part. Used a split aluminium collet between the threads and the chuck.
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