Look out for dodgy v/v collets

[oldchieft]

Hi all.
I have been buying bits for my project (Converting my Morgan from a Xflow to a Twincam) and I have found a worrying situation.

I have a head, valves, springs and retainers but I needed collets.

I bought them from a reputable source but found only four were the familiar black finish.

The others were bright steel finish.

When placed on the valve stem the dark finish ones were a neat fit.

The bright steel ones were not a good fit, they were slightly under size at the bottom and they touched at the edges but left a gap at the centre.

They also pulled through the retainer further then the ones most of us are familiar with and protruded out of the bottom.

I took them back and took the whole stock of the "old sort" hoping that was problem solved.

Later when trying them on the valves I found one was under size at the top, so this one just rocked in the valve groove, the top of the valve was flush with the top of the retainer.

The collet for its size is the most critical part in the engine. Just think for a moment what a dropped valve can do.

I suspect in the past these parts were made in a sintering process, the bright steel one were machined.

However the last one was also a dark finish and that one did not fit.

Has anyone else found rogue small parts we need to look out for?

Jon the Chief

[elanman999]

Jon,
Yes I have found something similar but my supplier (QED) were quite open about the issue. The "old" collets are no longer available. The "new" ones are not the same and so they now make new spring retainers to suit. They also still make retainers for the old collets.
I too did some tests and found that the new collets did pull through the old retainers more (about .015in) I did not see this as a major problem. In fact as I was fighting for spring space it was an advantage. I would also say that there was more difference between worn old collets and some unused old collets I have. The difference over the eight worn retainers I was using varied by over .010 in.
Edit, As we are talking about the insertion depth between two tapers it's hard to be very precise.

Another key question is are the new collets you have from the same source as the ones I have?
Cheers
John

[oldchieft]

Hi Jon
Mine were from Paul Matty, I was told that they were from the usual suppler.
In the end the store man went to the workshop and found some.

My head was from Tim Cousins at SAS and he supplied the valves, springs and retainers that he uses on his own race engine. He said his suppler did not have any collets.

Maybe they have had issues and had not found a new source of supply.

Jon the Chief