Still stuck on starting ( which spark plug for petter a1)

Hi all still stuck on petter a1 starting , I had a look at the plug and it has got a short reach champion plug in it, I don't think it right as it cant protrude beyond the threads, so looked around and from what I can gather , these engines run fine on NGK BP6ES , so I got one went to fit it, and it hits the valves and bends the ground electrode on the plug, can any one shed some light, seems a 19 length is wrong, even the lodge BL14 is the same length, what going on,john

A short reach plug is probably correct as some engines, Wolseley WD etc, use a short reach plug in a 'long reach thread' to help shield the plug and prevent fouling. My own A1 has a short 18mm plug as I had to drill it oversize as the threads were stripped! Just be careful that you haven't bent a valve, a lad at a local rally did just that a few years ago putting the wrong plug into a Petter.

Pete.

All my engines that take 14mm plugs I run NGK B7HS in and they work just fine

Thanks for that guys , I shall give that a try, as i was wondering that if the plug was shielded it might be another reason for poor starting and the wrong plug type, when the engine is running its good and good tickover too, but poor starting

You say that starting is poor, can you hear the impulse 'clicking' on the magneto when you turn the engine over? They can get stuck up with oil and sometimes need the mag removing and brake cleaner etc squirting into the mechanism to flush them out.

Pete.

Yes inpulse is working fine , with good spark too, just this engine seems be one of those stubborn ones, I think I might take the inlet and exhaust manifold off and look at the gasket condition too, must be a reason,john