Jung HZ opposed 2-cyl

[petertha]

Yes looks like similar vent nipple positioned here.

[petertha]

I translated the Jung document to English. The plot thickens. Larger valve clearance values & also different clearance values on INT vs EXH. When I compute the resultant open duration I get values like this.

[Jasonb]

That's quite a bit different to the theoretical cam value.

Have you got a link to the download, I could not spot it.

[petertha]

The link is located here
https://www.cad-modelltechnik-jung.de/construction-plans-model-engines.html

Attaching (MS Word auto converted German to English) of aforementioned documentation.

[petertha]

Relevant Jung verbiage

To adjust the  engine timing, the  position of the  camshaft towards the  crankshaft is  adjusted so that the two valves of the first cylinder (seen from the front the left) overlap exactly and the piston of the first cylinder is on OT. The valve clearance should be 0.1 mm on the suction side and 0.2 mm on the exhaust side, this is to be checked often, especially if the engine is still little run-in. After about 5-7 hours, the engine can be  considered as running-in.  After that,  the valve clearance does  not change very often.  The valve clearance shall   be checked when the engine is cold.  The camshaft is lubricated by the oil accumulating in the crankcase.

[Jasonb]

Thanks, I was not clicking the headings, just the image of the engines. Will download the ones for the engines I have drawings for.

[petertha]

Perhaps Jung had his reasons. I'm not sure the OS Gemini twin is directly comparable but the  manual shows 0.04-0.10mm, no distinction between inlet/exhaust valve.

[petertha]

Its taken me a while to figure out how to compute & plot the timing so that the EC (exhaust close) and IO (inlet open) events are equal angle about TDC and simultaneously factoring LSA (lobe separation angle) which in this engine is 90-deg, but I wanted it to also be an input variable as a generalized cam timing tool. Anyways, hopefully I have it figured now. I think this is how the resultant timing looks if you did it according to instructions at least. If you spot any errors let me know.