Josephine rebuild

[Srenner]

Pretty devastating to see. You're fortunate it didn't clobber the piston and transfer down the rod to flatten the bearing or damage the crank. Be sure to check the bottom of the tappet.

I hear your concerns about the other seats. Situations such as this present a challenge to optimism. We want to believe it was a one-off failure, but the smart move may be to replace them all. Cost is often a driver in the decision, but catastrophic failure can be, well, catastrophic and even more expensive in time and money.

As I have augured into old age, I find my approach is one of preemptive action rather than optimism.

[Keith Clements]

What is lucky is that this happened in my garage and not in the Dolomites.
I am trying to find a replacement seat Then need to see how I can replace. Then need to see how to fix the ones in there. My other heads have small screws holding them in.
I suspect the long lay off rusted the seat and valve together. Then when turned over the push rod bent trying to open the valve but also managed to loosen the seat. This was Ok in normal running but once I manually moved the valve to do the tappet adjustment it moved the seat completely out to lock the valve open.

[Keith Clements]

The head has been replaced with one from the engine used previously for racing, since the two engineering firms I previously used seem to have closed down.
The head has been shaved to give over 170psi so needs shorter push rods.
All good now so waiting for a sunny day. I may replace the head on the other side next week.
Also replaced the cam follower which may have suffered. It did seem to have more wear than the others and had not been rotating.

[Keith Clements]

I have a new theory on what happened. The seat slightly rusted on the valve during lock down. It was loosened when first started but did not come out being held in by the exhaust gas rushing past it.
Then during manual rotation it had chance to displace itself enough to lock the valve open.
Then when trying to check compression on starter motor the push rod bent.

[Mike Allfrey]

All very interesting, but I did not find the reference to the coolant pressure test. No matter, we will get over that one.

With regard to converting the electrics on my Jupiter to negative-earth when I installed a modified Lucas alternator, I solved the rev counter drive problem by having an electronic movement installed in my rev counter instrument by a local instrument repairer. He said that he programmed the movement to maintain the same indicator needle characteristics as before.

To valve seat inserts, I have understood that the inserts, being of different material, expand more greatly than the cylinder head's cast iron. Will have to watch out for that one!

All the best,

Mike A.

[Mike Allfrey]

Many Thanks Keith,

Most impressive. Please wait for my test photos! Method will be a bit different. Australian hardwood bungs in hoses!

Mike A.