Compared to the last model which I was very pleased with until I tested it was a completely different model

I’ve extensively reworked the valve system to create a solid bedding

I must have tried at least 10 to 15 versions until this one showed itself as the right one

What I found was switching from the first models valve holder system to the new one, there was a micro change in height which stopped the valves from working

Even though they’re in the same place, this was infuriating

I’d to then figure out a new cam follower system as the valve holder was working well, the search in my Lego parts bin was on

I had an idea of how I was going to do it, but wasn’t sure if I had the parts. I then found some very old parts

Part number 32557 came to my savour and yes it can be built with other parts, but this was a simple solution. It then enabled me to use two half pins and LEGOs 2x1 31 degree slope 85984

Amazingly, this sits perfectly on the tiny valves and works so much better than the 3 length beams used previously

The gap between the cylinder and valves is to the limit, but the engine also runs super smooth with it being so easy to turn by the tiny winding handle, it feels just like a normal Lego technic engine

This engine still follows the same principle for the 4 stroke cycle with the crankshaft rotating twice as fast as the camshaft. It works on the 1,3,4,2 firing order too

Those interested in the springs, these are 0.3*6*10mm and I found them on eBay. If found the accuracy on then can be out by as much as 1mm which at this size is a huge discrepancy when the valve only moves about 1.5mm, but they work and I'm happy

The timing is good enough for the inlet and exhaust cycles to open and close their valves while the piston runs that cycle required

This Twin Cam Lego Engine evolved from the first version
   • Prototype Twin Cam Lego Technic Engin...  

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