Engines > From Kits/Castings
Alyn Foundry CHUK 3 Mk 2
RayW:
Thanks to Graham very kindly digging out his one and only set of castings for me, my latest Alyn Foundry project is now under way in the shape of the Mk 2 version of the horizontal CHUK 3 flame ignition engine. The Mk 2 version features a rotary flame inlet valve underneath the cylinder, operated by a pushrod driven from a cam inside the flywheel.
Progress to date consists of machining the base casting, cylinder yoke, cylinder and piston. The cylinder is fully bored and honed to a nominal bore of 40mm and the piston is a nice sliding, almost airtight fight. The flame admission slot and rotary valve hole in the cylinder are still to be tackled.
Photo 1 shows the castings as received and photo 2 shows the assembled components so far, with the piston just peeking out of the end of the cylinder. In practice, the piston would stop just short of the flame port slot when at TDC.
Admiral_dk:
I see that you are of to a good start :ThumbsUp:
Per :cheers:
Alyn Foundry:
A good start Ray. :ThumbsUp:
Four of the castings are genuine Rhuddlan foundry and were cast a 1/4 of a century ago. Sadly the gentleman that bought them became too frail to machine them and approached me a couple of years ago about building it for him. Strangely enough I was actually in the throes of building one at the time so I basically exchanged his castings for mine and finished the job.
Here’s a photo of the Mk 2 along side the other CHUK family members. And one of the improved cylinder heads.
:cheers: Graham.
RayW:
Thanks Graham. Can you let me have details of the valve side of the cylinder head please.
Alyn Foundry:
Just a photo available Ray.
The casting was made dual purpose for this one. It can be bored out to suit CHUK 1 ( old style ) or used with a central compression spring as CHUK V. For horizontal use note the little pin which stops the “ Chipmaster “ valve from dropping off the seating edge. Obviously placed at bottom…. ;)
I made the stub into a “ chucking stub “ first and then machined all the faces from that datum. The central hole was drilled to 3/8” 10 mm to accommodate a light compression spring. The exhaust holes can then be drilled to any division that suits your taste
:cheers: Graham.
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