Kiwi Mk2 Engine

[vcutajar]

After trawling the forum for the last 2 weeks and learning new things from the postings, I have finally taken the plunge. I have decided to build my first IC engine. I also took a decision to use castings which is also a first for me. I bought the kit of the Kiwi Mk2 from Hemingway Kits (http://www.hemingwaykits.com/acatalog/The_Kiwi_Mk2.html). I would like to thank Mainer (Steve) for sending me photos of his water cooled Kiwi (mine is going to be an air cooled version).
The kit arrived by Fedex and it was nicely packed with each item individually bubble wrapped. I already knew from the sales receipt that the timing gears were missing but cheching through the items I noticed that the BA hex nuts were missing (not really bothered as I intend to go metric). Also missing were a piece of spring steel and most importantly the piston casting. I contacted Kirk at Hemingway who quickly replied that he would send the missing parts with the timing gears (when these become available in a couple of weeks).
As I know that everybody here loves to see the pictures I took some photos of the castings.

 

[vcutajar]

Some more photos

Front and back crankcase

 

[vcutajar]

Cylinder head, cylinder and crankshaft weights

 

[vcutajar]

Timing gear cover, conrod, carburettor and float chamber, contact breaker attachment

 

[chuck foster]

this should prove to be a most interesting build 8)

if memory serves me right this is an e.t. westbury design???

thanks for sharing and as you know we all love pictures. ;D

chuck

 

[metalmad]

Sounds like a great project
Ill be watching
Pete

 

[tel]

As will I!

 

[vcutajar]

Ok so today I decided to give it a start.

I do not have any running projects at the moment and for the last three months I have been fitting a Shumatech DRO550 which has been stored for nearly a year to my X3 mill using linear magnetic encoders. As you can imagine I am a slow worker.

I thought I would start with something simple, namely the tappet guide which is a bronze casting. After checking the dimensions of the casting, I faced one side. As you can see I cheated a bit by scanning from the plans the tappet guide diagram, made it scale 1:1, glued it to the faced casting and used it as a template. Yes, I know, not very professional. I then drilled and tapped the edge holes 3mm and then drilled and reamed the middle holes (from where the tappets pass) 5mm.

 

[vcutajar]

And this is the casting faced drilled, tapped and reamed on one side.

This weekend I will work on the other side. I intend to fix the casting to a piece of aluminium using 3mm bolts. At first I was going to use the faceplate to continue working on the casting and then I realised that at some point I will need to take it off the faceplate for milling. So now the plan is to use a rotary table instead of the faceplate and do all the operations in one setup. At least that is the plan.

 

[maverick]

Nice little project you have there. I'll be watching with great interest.

 

[vcutajar]

Today I continued working on the tappet guide. First I marked the the tappet guide so that I could rough mill it before putting it on the rotary table. Rough milled it and then I attached it to a piece of flat aluminium using 3mm screws. Put it in the vice and then milled it some more.

Tommorrow final operation on the rotary table, or is it going to be a faceplate. Decisions, Decisions. I will decide tommorow. First I need a beer before going out with the family.

 

[vcutajar]

Today continued work on the tappet guide and the rotary table was used. Machined the circular section of the tappet guide to 14 mm diameter. Then milled down the height of the guide to the proper dimension. Took it off the rotary table and cleaned the side of the flange with a Dremel. Cleaned the whole part using 280 grit and then 400 grit sandpaper.

Final operation was to drill both 3mm tapped holes with a 3mm drill. To locate the hole under the chuck I screwed the 3mm tap in the tapped hole, locked the tap in the chuck and then fixed the tappet guide to the rotary table. Removed the tap from the chuck and inserted a 3mm drill.

 

[vcutajar]

First part finished.

Maybe tommorrow I will polish it with a Dremel (at least the visible outside part). This week I do not think I will be doing anything else on the Kiwi as I have a day course (hate it) and then I am off to Munich (Germany) for some sim sessions (love it).

 

[vcutajar]

So here am I in Munich in the hotel room pouring over the Kiwi plans. Its too cold outside (at least for me) to go running around the city.

Having finished the tappet guide, my next item in the build is going to be the tappets, and I noticed a mistake (I was warned to watch out for these). Actually it's not a mistake but a difference between the diagram of the tappet on the 1960 magazine article and the diagram on the large plans. On the magazine, the bottom of the tappet, the cam follower (is this the correct terminology??) is drawn as semicircular (having the same radius as the tappet guide), whilst on the plans, the same part is rectangular. I suspect that on the article it was semicircular more for aesthetic than practical reasons. At the moment I am leaning more on doing the rectangular version for obvious reasons.

 

[vcutajar]

I was looking at the recess on the tappet where the pushrod fits and also the same recess on the rocker arm where the other side of the pushrod fits. They are both 3/32" and 1/8" deep but have a slight taper so that the pushrod does not bind at its maximum angularity.

I was thinking that instead of the taper I use a slightly wider recess like 3mm. Any ideas??

 

[vcutajar]

Finally back home where the temperature is more decent (18C). Whilst I was abroad I kept thinking about the above post (tapered holes for the pushrods) and finally came to the the conclusion that I need to try what happens if I use a slightly wider untapered hole (3mm ball nose mill). So tommorrow I intend to experiment on a scrap piece of steel and see what happens.

Also tommorrow I need to figure out, with the plans in front of me, the intended use of all the pieces of bar stock that came with the castings.

 

[vcutajar]

Today I drilled a 3mm hole in brass to the specified depth of 1/8" using a ball nose and tried the pushrod to see at what angle it touches the side of the hole. For sure the tappet will not be at this angle and I do not think the rocker will also need this angle. So unless I think of a better way I will use this method instead of the tapered hole.

 

[vcutajar]

Today I tried solving the jigsaw puzzle of the bar stock that came with the kit. I tried to match the pieces of raw material to parts of the engine. I was never good at jigsaw puzzles and did not match everything. At least the pieces of silver steel and bronze which are hard to source locally I managed to match.

I also sourced from my stock the pieces of BMS I will be using for the tappets and rocker arms. Did not do any machining today as the lathe was doing a funny noise which was due to a spindle belt soaked in oil. Could not change it today as it's a holiday.

Spent the rest of the day mostly looking at my youngest daughter playing Assasin's Creed online.

 

[vcutajar]

OK. Today I changed the belt for the lathe and this evening started work on the two tappets. Started with a 12mm round section BMS and faced it. I then centre drilled the face and drilled the tappet hole with a 3mm ball nose end mill. I then reduced the 12mm section to 5mm. During the final cuts all the time checking with the tappet guide. Brought it down to a slip fit with 280 and 400 grit sandpaper. I then parted off the piece. I did not part it off right through but hacksawed the last part.

Next operation will be on the mill with a dividing head to give the cam follower the rectangular section as per plans.

 

[vcutajar]

This morning I continued work on the tappets. The original plan was to put it in a dividing head on the mill and face the cam follower and give the rectangular shape in one setup. But that means I have to true up the dividing head on the mill table and I hate doing that. So, new plan. Put the milling vice on the table and faced both tappets. Then removed the vice and put the dividing head on the mill table and gave the tappet heads their rectangular shape without needing to true up neither the vice or dividing head.