[TR] Rocker feed screw.

[dave northrup]

I do believe that the float bowl top bolts and the bolt on the starter are Whitworth on the sidescreen cars

From: Triumphs <triumphs-bounces at autox.team.net> On Behalf Of Don Hiscock
Sent: Wednesday, April 30, 2025 6:26 PM
To: John Macartney <johnbmacartney at gmx.com>
Cc: triumphs at autox.team.net
Subject: Re: [TR] Rocker feed screw.

Thanks, Jonmac.  Most likely Sweden mandated a move to zinc and away from cadmium.  Cadmium plating has some health and environmental risks that are lessened with zinc plating.

On Wed, Apr 30, 2025 at 5:20 PM John Macartney <johnbmacartney at gmx.com<mailto:johnbmacartney at gmx.com>> wrote:
Don,

It came about as I recall sometime in the late 60s when I was working for the company in London. What started it (IIRC) was when there was an engineering change bulletin brought about by Sweden requiring cadmium plated fasteners instead of zinc, or t’other way about on all cars for Sweden. That allegedly precipitated the Belgian assembly plant seeking to use metric fasteners in certain areas, though not all, in their build sequencing. Coventry still built quite a lot of components that went into the kits for Belgium and for a while, most if not all cars going to Sweden were built in Belgium. Later on, Sweden destined cars reverted to UK build and I think it all died a very quick death and we reverted to imperial standard, apart from the cadmium and zinc issue which remained in place. However, it wasn’t plain sailing all the way in the Coventry and London service departments because the fitters started moaning about not having appropriate sized sockets and spanner’s for oddball UK home market cars that found their way in with strange metric hardware. All in all, one humongous cock-up all round and I don’t think anyone was sure who had suggested it all in the first place. Probably some acne ridden long-haired lout just out of university with a Divinity degree and who wanted to make his mark and change the world. Quite likely the same person was later moved into Purchasing and decided to change the metallurgical spec for Stag cylinder heads - and that’s somewhere no-one needs to go, EVER!

Jonmac

On 30 Apr 2025, at 23:34, Don Hiscock <don.hiscock at gmail.com<mailto:don.hiscock at gmail.com>> wrote:
I'm not aware of any Whitworth threads installed by S-T (at least on a sidescreen car).  There may be some Whitworth and BA threads on bought-in components, like SU carbs, Smiths, and possibly some Lucas.  But I'll be shocked sh*tless to learn legit Withworth threads were used in a S-T engine.

Jonmac, I'd never heard that metric and inch fasteners were used on the line at the same time depending on the end market for the vehicle.  That's a fascinating bit of trivia, and one of the reasons we love having you here!  What time period are you talking about for that?  Maybe 1970s?

On Wed, Apr 30, 2025 at 4:27 PM John Macartney <johnbmacartney at gmx.com<mailto:johnbmacartney at gmx.com>> wrote:
I have my doubts about the offending item having Whitworth ancestry. While I’ve long been a Whitworth advocate and enthusiast (for purely patriotic reasons) I think it might be worth going down a metric route. There was a time when the factory briefly reverted to metric hardware that was market specific for European build. Needless to say, certain bits of hardware went where they shouldn’t (or inadvertently wound up there). Might this be a possible avenue to explore? Evaluate metric fine and coarse pitch threads.

Jonmac
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