My spark plug short circuited

Here's A Smoking version cheap!

 

More expensive than a type 4 ready to fit though

 

That's something I dread happening - which is why I keep my speed down to 55/60 on the motorway and the revs down otherwise - good luck with the replacement

 

There was really no partucular sign of trouble. I had just climbed a hill on the M27 at less than my usual speed as I was creeping up the left hand lane inside two lanes blinded by the sun. Came over the top of the hill, overtook a truck and then dropped back into the left hand lane and slowed down. Vibration started but then the vibration stopped and restarted three times. Second time was loss of power.
Third time was as I pulled onto the hard shoulder.

If anything I was driving 40-60 mph rather than thrashing it.
I even changed down into third on the hill as the traffic was slow.
Normally I hit the bottom of that hill at 68mph and slow to 60 as it steepens.

Really there was no warning.

The only thing is that I know my engine had a sweet spot around 4400 rpm about 68mph where temperatures are stable.

Despite my reputation, I do keep the rpm below 4500 but will hit that regularly.

Slowing down the oil temperature drops but the CHT tended to go higher..
But its nothing the engine had not done hundreds of times before .

I had lined up a new set of stock valves to replace the valves in those heads but the ones in that engine were stainless and had been moved across with cylinder heads on my engine rebuild about 3 years ago. Before that they had done maybe 50000 miles. So the valves were older.
Heads were cracked but had stayed the same over the 30000 miles since last rebuild . Had lapped the valves about 4k miles ago. No real sign of receding valves/stretching stems on the last adjustment.




I think that valve was hammered while it was so hot that it was soft.

 

Oh bugger Mike thats a bit second hand!