Will 1850 Collets fit a Sprint?

[James467]

I have lost a collet and need another pair!!

Part numbers are different, 154060 for a Sprint, 106663 for an 1850.

Ta
James

[tony g]

This listing suggests they will fit. Its robsport btw
http://www.ebay.co.uk/itm/Triumph-STAG- ... 2L-G5JPJRA

Tony

[MIG Wielder]

It is interesting that the very late 1850 engines > VA81976 have the same collet caps as the Sprint ( UKC 1902 ) but the early ones are different ( 148886 ). But there are no other changes to the valves or the collets themselves.
I did some measurements on an old 1850 inlet valve.
Stem dia; =7.86 mm
Top of valve to top of the hemispherical undercut where the collet fits = 2.84 mm.
Max depth of hemispherical undercut = 6.27 mm dia,
Length along the valve stem of this hemispherical undercut = 2.48 mm

If you can compare this with a Sprint valve it might help.
As Tony says it might be safer just to get Sprint ones.
HTH,
T.M.

[James467]

Measured my inlet valve.

All the same apart from the stem dia - 7.12 on mine
Top of valve to top of the hemispherical undercut where the collet fits is the same - 2.84 mm.
Max depth of hemispherical undercut, same - 6.27 mm dia,
Length along the valve stem of this hemispherical undercut, same - 2.48 mm

I also got some 1850 collets from Rimmers to test them and you can clearly see that the 1850 ones are bigger, looks like to accommodate the increased stem dia.

154060 (Sprint) on the left, 106663 on the right







You can see the Sprint collet fits the valve nice and snug. It's not worn, just moved slightly in the photo.





Whereas the 1850 collet on a Sprint valve does not

[xvivalve]

Bugger!

I have a pot into which I have arbitrarily thrown Sprint, 1850 and TR7 collets over the years; that's a job for Me, 'mike' and a wet Sunday afternoon then!!

[Jon Tilson]

Lol....

Even the greatest of us live and learn. I expect I have a similar bucket but wouldn't own up to it on here.

Glad we all know now....

I wonder how many Sprint valve drops have been caused by this?

Jonners