Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Pinking - another possible cause

Dan. My thoughts are that an even 360 degree firing would do away with the Centa while the counter balance shaft would would help with secondary imbalance. Allow me to clarify that when I wrote 'offset crank pin' that I was describing a single crank pin being split (as used by some V6 car engines). I think a 90degree V-twin would be a better option to do away with the Centa, just my opinion though.


Back on topic;
So it was the damaged camshaft keyway key that allowed movement on the cam cog, which changed the timing, causing the pinging/overheating leading to the cylinder head gaskets to go. The question then is what caused the damage to the key. Perhaps extra keys should be carried as spares along with the usual suspects.

I think the toothed pulleys in the timing case are all sintered (produced by a technique known as Powder Metalurgy) and therefore have a lower mechanical strength than if the pulleys were cut from steel and then suitably hardened
If they are not a really good fit on the shafts and their associated keys, any rotational clearance will allow the pulleys to rock backwards and forwards and the keyways in the pulleys will widen due to the on and off effect of the load. This widening of the keyways will allow angular movement which will alter the timing of the valves.

Only a theory but maybe a possibility?

Keith

Another theory:

S&S changed the specification of the camshaft pulley nuts from a flanged serrated type to a flanged, non serrated type intended to be used with Loctite. I'm not sure when this change took place, but it's documented in their literature as well as in a post or two on this forum.

The specification change was no doubt for a reason, perhaps that reason being the nuts were not sufficiently keeping the pulleys immobile relative to the camshaft?

Would be interesting to know which type of nut was used on the damaged engine.