Cam bearing cap stud, C2326


(Roger King) #1

I’m planning to make an adaptor for valve spring compression that threads into the cam bearing cap bolt holes to lever the valve open for removal. Can anyone tell me what the thread is for this stud? Is it 5/16 BSW, or 5/16 UNC? Checking against a die nut, neither is an easy fit and I don’t want to risk damaging the head thread by making a stud with a marginally incorrect thread - they’re pretty close to each other.
I can’t imagine Jaguar using UNC threads, but you never know…


(Roger King) #2

Sorted it - it’s 5/16 ANC, according to Viart. ANC is what the Americans call UNC!

I’m making up a simple thread adaptor to use an overcentre lever valve spring compressor designed for US V8 engines. I now just need to make up a tubular section with ‘windows’ to press on the spring retainer and allow the collets to be removed and it’s done. It’s a nice piece of kit because the overcentre lever locks in the down position, making collet removal/insertion easy with both hands. It’s great for changing from break-in springs to race springs as it doesn’t require head removal. Just keep the valve up with an airline.


(Rob Reilly) #3

The XK engine was designed at the time when British industry was converting away from the Whitworth system, so is all ANF (USA = UNF) threads, except where they thread into cast aluminum where they use ANC (USA = UNC) coarse threads, and the carbs which were made by SU and were still on the British thread system so are BSPP. Chassis and front suspension is also ANF/UNF from the beginning of Mark V and XK120, but body and electrical fasteners converted later. You may see this system called SAE for Society of Automotive Engineers, or US Sellers threads because an American named Sellers invented it in about 1860.


(Roger King) #4

Also still a fair few British Association (BA) threads in there, as there are on my Land Rover and AC. Oddly BMC moved away from those early, I can’t think of a single one on the Mini of '59.


(Roger Payne) #5

Roger,
Its somewhat more complex than that.
Pre-war UK used Whitworth exclusively, thus BSW (for coarse threads >1/4" dia), BSF (for fine threads >1/4" dia) and BA (for small threads less than 1/4" dia). THe USA used National Course and National Fine (NC and NF) but commonly referred to as SAE, and a NF based smaller thread.
During WW2 where British and American forces shared vehicles and workshops, confusion ruled with neither Brits nor Yanks (in our generic reference to all USA Nationals - sorry if not politically correct) knowing each other threads and fastener and spanner implications.
So there was an agreement between the ABC Conferences (American, British, Canadian) re adopting a common thread/fastener/spanner system, to be called the Unified System that included UNC (course), UNF (Fine) and UNEF (Extra fine for small threads) with all three countries to revise their existing standards and introduce new National Unified Standards.

Independent observers generally thought the Whitworth system superior to the SAE system, but for reasons probably as expected, the Unified system meant to be an amalgam of the best features of Whitworth and SAE, ended up being far more closer to SAE than Whitworth. The new British Standards on Unified threads, fasteners and spanners were not introduced until the early 1950s, but with post-war production commencing late 1945, the various industries made their own choices what to do. In Jaguars case the SS-Jaguar continued being made, but now called a Jaguar (Mark IV), but retained all its Whitworth Engineering. The new model Mark V Jaguar and XK120 Jaguar however was engineered in anticipation of the yet to be released Unified Standard still not written/implemented, so was referred to as (American) National Course and (American) National Fine, but simply as ANC and ANF. But Jaguar only controlled what they made themselves, and still were reliant on whatever their suppliers used, and indeed SU (supplier of fuel pumps, carburetters etc) continued using only Whitworth system well into the 1970s and then onto metric (and never adopting ANC/ANF nor once the standards had been introduced UNC/UNF). But most (not all) other suppliers did transition to ANC/ANF then UNC/UNF quickly. But as much as the British Industry were happy enough to abandon Whitworth and adopt Unified for threads 1/4" and greater, this was not the case for small threads less than 1/4", thus major suppliers such as Lucas, Smiths, Wilmot-Breeden continued to use BA.

Net result in 1950s and 1960s Jaguars starting Mark V and XK120 you get initially a mix of Whitworth and ANC/ANF threads with ANC/ANF giving way to UNC/UNF from about 1952/3 onwards (so from XK120/Mark VII - but not Mark V) and a rapidly diminishing use of Whitworth from most suppliers apart from SU systems that remained Whitworth. But throughout all the small threads in the electricals and instruments and many WB supply items remained using BA threads/fasteners.

Now it should be noted that at the day to day practical level of fasteners/threads/spanners interchangeability that the anticipated ANC/ANF was virtually the same as the SAE system, but once the UNF/UNC system was introduced other aspects such as tolerances and material strengths were more Whitworth.
The only main difference for the mechanic/restorer with UNF versus ANF/SAE is with the 1 inch diameter size. A 1" SAE/ANF thread is 14 tpi whereas a 1" UNF thread is 12 tpi. Does this affect an XK/Mark owner? Most certainly. See how you go finding a replacement slotted nut that secures your rear hubs onto their axle-shafts. They are 14 tpi SAE/ANF threads, nut the slotted nut dimensions are more ANF than SAE - but a 1" UNF slotted nut wont fit.

But be careful if doing any work on Instruments and Electrics - as they use BA threads/fasteners for sizes less than 1/4" (as also in an XK120/140 OTS windscreen frame) and other locations. DONT ignorantly force in small UNF fasteners.


(Roger King) #6

Thanks Roger, interesting info. I have good stocks of BA fasteners for instrument repairs, and some of the ‘instrument thread’ fasteners that were also used in some applications. My 94-yr-old Dad repaired instruments during and after the war and still has a few parts kicking around.
A pic of the spring compressor adaptor, and the tool in action ( in the locked open position):



(Mike Spoelker) #7

Actually, finding 1“-14 hex nuts that accommodate a cotter pin is easy. McMaster-Carr stocks them. What is more difficult to find are 1"-12 nuts that accommodate a cotter pin.


(Paul Wigton) #8

The Moss gearbox was also still Whitworth, at least the heads of the bolts were.


(Roger King) #9

My 1967 Land Rover chassis parts are almost exclusively Whitworth, and I think BSW was used for quite some time after that, into the Defender period, some parts up to 2016. Similarly, but obviously not in such large production numbers, the leafspring AC Cobra chassis fasteners are all Whitworth threads. Not sure what happened with the switch to coil springs in 1965/6, though. A fair bit of Whitworth is present in Morris Minors, Sprites, Healeys etc…
I don’t remember coming across UNC/ANC threads in British car engines before - the only sixties cars of my experience with these threads are Mustangs (obviously), and the Cobra’s Ford engine. But a) I’ve never played with Jags before now, which obviously did turn to the dark side quite early and b), no sane person would rely on my memory.


(Lee140FHC) #10

We are Jag owners, sanity be damned!


(Roger Payne) #11

The thrust of my detailed comments was with respect to Jaguar, and thus not necessarily relevant to other marques.
Pre-war SS Cars, and immediate post-war Jaguar, as well as all their suppliers, used exclusively WHITWORTH - thus BSW (Course), BSF (Fine) and BA (<1/4in) threads and fasteners.
Starting Mark V, Jaguar started to now engineer their cars in the anticipated new Unified system not yet proclaimed in a yet to be produced British Standards, so as good as they could in ANC/ANF but still BA, but carry over engineering from Mark IV was still in BSW/BSF, and most suppliers still Whitworth only.
The XK120 - especially the new XK engine was engineered in ANC/ANF thus further reducing any Whitworth carry over, and from about 1952/3 now introduced UNC/UNF. But still dependent on suppliers to use whatever they were building, so yes Moss Gearboxes still Whitworth, and as before SU stayed using Whitworth until the 1970s then changed to metric.
This is a big part of identifying fasteners used, as although Jaguar predominantly used BEES brand bolts/setscrews, and thus across the XK120 in Whitworth, ANC/ANF then UNC/UNF sizes their suppliers may have used other brands, indeed the Salisbury rear-axle assembly uses Rubery Owen branded bolts/setcscrews. The bought in SMITHS Jack has a WODEN and a SPARTS brand bolt/setscrew.

All good fun for those into such things, but the bottom line is if you own a 1940s/50s Jaguar you really need a set of Whitworth tools/spanners (including BA) as well as Unified (AF) tools/spanners

Most British Industry were forced to adopt Metric in the 1970s, so although claiming ZERO knowledge of Landrovers its most surprising that the Defender still had anything Whitworth after the 1970s, let alone 2016.

There are ways of identifying UNF/UNC from ANF/ANC, but for the casual observer the same spanners and threads are used (apart from the sole 1" size).


(Roger King) #12

It’s interesting stuff, Roger, and a lot there I wasn’t aware of. Working on marques ‘new’ to you is always a really exciting adventure (you can guess what my wife thinks of this) - it’s fascinating to see how they differed. Those times have gone! Most of the fasteners on my 140 (Bees) are in good useable condition, so hopefully they can be re-used.
But yes, Series Land Rovers and Defenders really are a breed apart, real throwbacks. It’s actually incredible that what is basically the same vehicle went on for so long, and no surprise they gave up trying to keep it legal in 2016. Remove the plastic bits inside a late-model Defender and there’s a lot of very recognisable Series 2, or even a few Series 1 parts hidden inside. The basic architecture hasn’t changed at all and as far as production and fastener spec goes, why change it if you’re not changing the part, I suppose.
This is the first XK engine I’ve stripped, and am very impressed with the design and degree of simplicity and restrained over-engineering. And I’ll keep an eye out to be careful with the rear hub nuts.