Well, my rebuilt x-flow has run once more - 15 minutes at 2500rpm, to get the cam bedded in (yes, I know it needs a bit longer yet). Whoopie! It's a great relief to hear it start and run once more, and it sounds very sweet.
The 'slight problem' is my spark plugs - I keep ending up with one or more of the plugs getting a cracked ceramic. Now I know that this is my fault, but what is the correct technique? This time, I used a proper plug socket, the rubber insert's been removed after much advice on this forum, and I used a T-bar to ensure that I turned it without tilting or going off-line.
I've never had this problem with previous cars or bikes, but I must have cracked 3 or 4 since first getting this engine. Is it a Ford thing? Or a problem with NKG plugs? Or is it simply me being heavy-handed?

cheers,
David

It migth just simply be you

Quite likely!

I forgot to say that it's the top ceramic bit that gets cracked, between the body and the metal top.

DJ

I've fitted thousands of N.G.K plugs as well as other makes , can't remember the last time I broke one fitting it or even taking one out for that matter and I still use the rubber insert in the socket. Suspect you may be putting sideways pressure on the plug when tightening. Try using a longer extension when tightening plugs and holding at the top so that extension stays in line with center of plug if that makes sense. Suppose like most things it comes with practice, hope this helps . Rusty

Last time I broke one I dropped it because it was still hot . I use the rubber lined socket with a short extension in it and tighten it by hand without the ratchet or bar. When it stops I then put the ratchet on and just give it the last half turn to seal it, don't go mad. N.G.K. are my plug of choice for most applications.

AS my late father once commented to me "you aren't doing up a flamin' steam fitting son!". Have you checked the manual to see if there is a torque wrench setting for the plugs (no, I'm not kidding)? If there is this would give you some indication of how tight they need to be.

What's annoying me is that I've worked on dozens of engines over the years, car and motorbike, probably fitted hundreds of plugs, and don't recall EVER breaking one in this way - it's just on this engine.

I've used my longest extension, a short T-bar (to avoid over-tightening) and usually finish with a torque wrench. I always try to keep everything straight and in-line with the plug.

I might investigate the socket - I had to buy it for this engine, and don't use it for anything else, so I wonder if it isn't fitting properly...

rgds,
David

[Edited on 7/2/05 by David Jenkins]

I had the same problem on a mini once. Again, I have changed hundreds (probably thousands) of plugs with no probs and then broke 3 in a row!!

Try a different manufacturer, I am not saying there is anything wrong with NGK (I use them) but just try it and see.