I think the original Seidel is a 7-70...at least that's what it says on mine! They also made larger ones.
I was extremely careful breaking mine in, I bought it from a guy who had it for almost 20 yrs. and never ran it !
I did notice that the valve clearances were somewhat uneven...I would set a valve to specs. than rotate it a few times and saw that when fully opened on that cylinder again the valve would have a different clearance!..I suspect that the cam that activates the 7 cylinders pushrods is not 100% accurate possibly.
As mentioned, I used the Microsens Glo system from Austria which has worked flawlessly...it will turn itself off automatically when the glo temp. is sustained ....some batt. usage is happening during each flight.
I had about 10 gentle test runs to break the engine in to full power and only to actual flights before my wing tip caught a fence post and is out of action til I get it repaired.
But the engine ran really well and had great power, but the torque is what surprised me with a large 24x6 prop on a 1/4 size Fleet Biplane.
I was also worried about spare parts, but figured finding a good machinist would be the way to go if anything broke.
I do know that the Evolution is a copy of the Seidel ( they sold them the patents and plans) so maybe the parts are interchangeable also.....