Timing Wheel
 

I fancied jiggering with my valve timing so I bought a wheel off ebay ... It's made of carboard!!!!!

Can't help but think that this is not a precision instrument

I take it a proper one is perspex or metal or something of the sort??

Mines Metal and has lasted really well, I bought it back in 1981 from Dixon racing, I don't think a cardboard one would have lasted this long