Help Please;;;;;;
A guy gave me 3 engines. I do not know how to tell between the 28cc & the other size engine. All 3 seem to have the same stroke of about 29mm & piston dia of 32mm, 2 have cylinder cast the same so as you can use socket & extension to remove cylinder, other one has fins cast over bolts with small hole to get to cylinder bolts. Spark plug is angled into the head, not straight up & down.
Any help would be great.
Cheers.

the angled spark plug might be a 10-10..... 54.7cc if i'm not mistaken

The engines are 23.3 CC. Volume = pi x r2 x h = 3.1416 x (1.6 x 1.6) x 2.9 = 23.3

What size prop should one of these spin. I fired one of the engines up yesterday with a Master airscrew classic 20x8 with 1 inch cut off each tip, It tached at 5200. Temp was 89.6F humidty was 36%. Fuel was normal unleaded with coolpower syn oil at 50:1. I see on a thread elsewhere that the engine size should be on the cylinder behinde the muffler,but nothing there.
Cheers.

Try a 16 x 8 or 16 x 10. They will probably turn them about 7500-8500. The small engine like to turn up to give any power.

p.s. It's McCulloch by the way.

Well i guess with a bore & stroke as it has + the chamber in the head that would equate to about 28cc would it not? Are these engines any good to fit into a plane? or they too heavy. If so what sort of plane would suit them?

Sorry to be so late, just saw the thread and answered anyway.
The combustion chamber volume does not have anything to do with the capacity, but it does dictate the compression ratio.

Swept Volume (capacity) = D x D x 0.785 x Stroke. (dimensions in Cm)
Where D = bore, S = stroke.

CR (compression ratio) = swept volume + combustion chamber volume, divided by combustion chamber volume.

(to measure the stroke, measure from crankshaft centre to crankpin centre and multiply by 2).

The 28cc model would probably suit a 1/4 scale model maybe 84" wingspan.

You probably know all this by now anyway!
Cheers, Will.