Dismantling a Javelin Cylinder Head

[David Morris]

Hi All,

I was once completely stumped, during a renovation of a cylinder head.

I have to admit that the cylinder head was not from a Jowett, it was from a Morris 1000, but the same story applies.

I tried my best to use the conventional valve spring compressor to dismantle the valves, and they just would not co-operate, being firmly stuck and preventing me from stripping the head and getting the valves out to renovate and/or replace. The Terry's spring compressor I was using threatened to fracture!

Faced with failure, I swallowed my pride and toddled off to our local engine refurbishers, Beals of Bath. They were a long-established company and now sadly missed. But at this time, about 10 years ago, they were still in business.

I carried the head into the workshop at Beals and asked for help, feeling rather shamefaced!

The head sat on the solid steel counter top. The burly shop owner just reached down to the shelf below the counter and produced a well-worn and heavy hammer.

He then struck each valve top a good heavy blow, and said, "now try again". There was no charge and I went home, doubting that I could continue with the dismantling.

But he was right, everything then came apart easily. The problem had been that the collets were seized onto the valve stems and were not prepared to come apart until shocked into submission by the blow from the hammer! The moral is that sometimes a good hammer blow solves the problem!

A sidenote is that on a Javelin/Jupiter, I found it difficult to get a conventional spring compressor to fit inside the combustion chamber. I made up a jig with a chamfered wooden block with two pads that fitted inside the combustion chambers, that then made the base of the block parallel with the top of the Javelin head, whilst holding the valves stationary inside the combustion chambers. I then made up a tube with a cut-out that just fitted over the top of the spring retainers, and a shaft coming out of the top. Then I put the wooden block under the head and mounted both the wooden block and the head onto the base plate of my pillar drill. The tube with the cutout fitted into the chuck, and by pressing down on the chuck lever, the tube with the cutout pressed the top of the spring retainer down, so that the collets cold be easily lifted out from the tube, through the cutout and with the help of some snipe-nosed pliers.

Of course, I remembered to thump the tops of the valves before I started, as I was taught at Beals!

I have hopefully attached a few photos of the jig.

All the best,

David

[Forumadmin]

I usually hit the compressor cup that is pushing on the retainer with a plastic mallet to achieve the same when removing. But I also do the same after fitting collets to make sure they are bedded in. Then check there is a gap between the collets. If there is not you will quickly drop a valve.

[RichardMc]

I put an old 19mm socket on the valve cap and give it a wallop with a hammer, you can feel it when it lets go as the bounce changes. Same thing just another way of doing it.

[David Morris]

Hi Richard,

Yes, that's a good solution. It's amazing what a difference a thump with a hammer makes! But I know what you mean by the feel, you can tell the spring assembly is free by the 'bounce'.

With my Jowett generator, I am just dealing with side valves now, but at least I can just unscrew the valve spring retainer. The hammer's back in the toolbox!

All the best,

David