67 replies to this topic

[rodomo]

Whitworth is 55 deg thread pitch, UNC is 60 deg.
Cheers
Dave.

Correct? Maybe? I didn't google it But I think also, from memory, the point of the pitch is different?

[Dr Terry]

Probably because it is basically an American design engine containing parts made in Canada.
The bolt threads might be UNC, UNF etc but the hex heads would be imperial A.F.

That's the SAE standard, ALL UNC/UNF original bolts had imperial A/F hex heads.

There are some exceptions in later model cars however.

In many brake systems the 3/8" UNF pipe nuts have 10 mm A/F hex size, probably just to keep tooling simple.

The VK EFI 6 engine is another mix of standards. Most of the basic engine has SAE A/F style bolts, the same as they had been since the intro of that motor in 1963, but the EFI bits (inlet plenum, throttle body etc.) are metric. The V6 is similar, that motor also originated in the early 60s & is essentially designed & built in imperial measure, however a lot of the modern additions & fittings are metric.

I'll throw anther spanner into the works, or is that a very bad pun. Where UK & US threads do differ is in the plumbing fittings (heater hose & manifold vacuum fittings etc.). The yanks use NPT (national pipe thread) which is an SAE thread, but the poms stuck with the even more common BSP (British standard pipe). But there is no 'metric plumbing thread', so they use BSP as the 'metric' plumbing standard. So things like M/Benz, VW & Toyota etc. which you would assume to be 100% metric, use a British standard for all their plumbing fittings.

This applies to the VK 6-cyl engines also. The 3.3 carby motor's inlet manifold has NPT threads for the vacuum fittings. These fittings were plastic for all Blue/Black motors, but were the same threads that had been there since the EH days. The VK EFI's inlet also had a plastic vacuum T, but it had a BSP thread.

Dr Terry

[rodomo]

My collection of Whitworth/BS spanners.

When I started my apprenticeship we were given 1 A/F toolbox and 1 Whitworth toolbox. At the time, the bus fleet were pommy AEC's. The bus pictured (AEC Mk 111) were still in service here in Melb.in 1974 hence the Whitworth tool kit.

Also, my "clunker" ratchet.

I also have a socket here marked 25/32" SAE but I cant get a good pic of it.

Attached Files

•  spanners 1.jpg   210.42K   1 downloads
•  spanners.jpg   193.3K   0 downloads
•  ratchet.jpg   225.22K   0 downloads
•  Mk 111.jpg   8.62K   0 downloads

[wot179]

Nice ratchet.

Looks like a Hazet.

[wot179]

Looks like something out an old motorcycle tool kit.

So maybe BSC (British Standard Cycle)

[wot179]

We were just chatting about this ol fred in the shoutbox so I thought Id bump it up cos its interesting.

[N/A-PWR]

+1^

[TerrA LX]

[Warwick]

I once owned an 89 XF ute. (Not something I'm proud of but there was no Holden equivalent in my price range at the time)

One of the bolts that held the ac compressor bracket to the block broke the head off. From memory the head was 15mm and as all the other external engine bolts were metric I thought it would be a 5 min job... except I frocked around for hours trying to find a bolt to fit. I pulled everything off, inspected the hole in forensic detail, scratched my head repeatedly and swore at it non-stop.

Then for the hell of it I tried a UNC bolt and bingo! So in despite of them having metric heads the bolts were hybrids as the block had imperial threads.
No doubt the way to fit a 60's engine into a metric production line.

Cheers,

Warwick

[rodomo]

I have a 2 BA Sidchrome spanner. Damn hard to get a pic as it is virtually unused and the chrome like new.

[IMORAL]

Rob. I thought I had the same spanner so went and checked. Strange thing is the ring spanners all have BS except the 2 is BA
Bought these 25 years ago. As you can see only used them
A couple of times as I was only at that washing plant the first year of my apprenticeship.