25-07-2020, 04:51 PM
(25-07-2020, 03:02 PM)Malcolm Parker Wrote: I would get the fuel level right and see how it goes with the Ruby head before swapping it for the earlier head. You might find that all your problems are cured!
+1 for that suggestion. It's always best to fix the problem rather than the symptom IMO. I've never noticed any particular harshness running a '37 head, but they certainly don't work well on engines that burn a bit of oil because of the daft position of the plug right above the bore edge. There is a noticeable difference between an oiled and sooted plug, so it's worth taking a bit of time to see which you have.
Before changing to a really soft (hot) plug, bear in mind that if the plug grade is too soft/hot, you won't get any soot on it at revs, no matter how rich the mixture is because the plug will be overheating and will have a "bleached" appearance.