[StuartMac]

Hi,

rebuilding rocker boxes.

Can of worms, for various reasons ...

washers
Seems to be a lot of copper ones

There should be only four copper washers total, one each side of each feed banjo.

Need to work out what order all these washers went in.

In theory, there is a sketch in the '71/'72 workshop manual; in practice it's wrong ... (shows the pre-'68 assembly order).

You should follow the order shown in the '72 parts book - (hardened steel) plain washer each side of each rocker, Thackeray washer between plain washer and side of rocker-box. However, even that isn't completely correct, it continues to show/list the 3/8" ID (E1330) washer at the feed end of each shaft; you'll need to replace each with another E1575 (1/2" ID).

Nevertheless, before beginning assembly, you'll need to decide whether to have the rocker shafts 'grooved', which should have been done since the '68 changes ...

Background
During '68, BSA R&D at Umberslade Hall advised a number of changes, primarily to avoid the cost of drilling rocker arms (which could also weaken them) and pushrod balls for lubrication.

Meriden made that change but - imho in a pretty-poor abdication of management responsibility - didn't make the associated changes to either rocker shafts (machining an oil transfer scroll on the shaft) or the washers assembly order, both of which were necessary to maintain the lubrication previously supplied through the aforementioned drillings. The result is, while the rockers and actuation continues to 'work', it isn't for as long.

@Shippy posted he had a straight oil-transfer groove cut in his 500's rocker shafts with a simple Dremel.

Hth.

Regards,

 

[StuartMac]

Hi,

oil gauge
teeing to run a pressure switch.
switches are set for 7-11psi.
gauge wasn’t very detailed at lower pressures, but I reckon it barely pushed 7 before switching. Likely around 5,

Depends. Your photo. shows you're testing a pattern switch, not an original Smiths. If that pattern switch is NPS thread, it's sold as a replacement for the '74-on switch, which Smiths supposedly rated for 3 psi ...

at revs it’s can be in the 50-80lbs, and in the 20-25 at idle. Given this would it be that bad an idea to fit a generic switch more suited, say one preset for 20psi… ?

It would be a bad idea, unless you want to be freaked after every spirited run in hot weather ... then the pressure can fall well below 20 psi, although still be perfectly-adequate.

The whole idea of oil pressure switches on Triumphs and BSA's was a mortally-stupid one, because no-one actually knew how widely the oil pressure varied between hot tickover and cold maximum. Cue dealers inundated with punters complaining about oil pressure warning lamps flashing at tickover on their new bikes; strip-downs rarely if ever found any lubrication-related problems; cue the factories fitting lower- and lower-pressure switches ... 😖 Otoh, if a twin runs 50-60 psi above about 3,500 rpm when hot (and a triple 70-85 psi), if an OPW lamp switched by even a 20 psi switch comes on when the engine's above that 3,500 rpm, the engine's donald already. 😖

If an engine maker's going to fit an oil pressure switch, far-and-away the more-important manufacturing requirement is consistently-good oil pressure at all rpm for hundreds of thousands of miles in every engine made. For this reason, engine makers apart from Meriden haven't fitted feeble plunger oil pumps for decades,

If you're running an old Britbike, knowing you'll never have consistently-good oil pressure at all rpm for hundreds of thousands of miles, if you must be able to monitor pressure in real-time, only a gauge works. However, then you must learn what the gauge is telling you - e.g. after the aforementioned "spirited run in hot weather", the pressure from particularly a twin's weedy oil pump will be lower than what even the Triumph workshop manuals say. Is it a problem? Only you'll know by stripping your engine ...

Hth.

Regards,

 

[StuartMac]

Hi,

anyone know if there is any advantage to rearranging washers without grooving shaft? If no clear benefit I may have to go ahead and assemble as per factory manual...?

You should follow the order shown in the '72 parts book

Ummm ... if there wasn't an advantage/benefit, why would Meriden have changed the washers order in the '72 parts book (admittedly still a half-arsed change), and then machined the oil scroll on the rocker shafts from '73? Parts books were reissued every year, workshop manuals were only updated, at best. Afaict, reassembling '72 rockers "as per factory manual" (workshop manual?) is probably the worst you can do?

rocker shafts grooved for an oil way either with dremels and jigs or via the expense of a machine shop (i'm not thrilled on either), and noticed this point made;

With respect, you have not noticed, or ignored, more important things in the same thread:-

. It's a 500, rocker feed isn't the same as a 650.

The groove dimensions are not critical and can be done with a Dremel. An alternative is to grind a shallow flat on the shaft. Whether using a groove or a flat on the shaft, they should be positioned at the top in the unloaded area between the rocker and the shaft. I made a pop mark at the outer end of my shaft to able to confirm the correct position of the shaft when assembling and tightening things up.

When the bikes were new, any factory's primary criterion was cost - the cheaper they could build it, the more profit made when it was sold. Coupled with that was the tiny warranty period before any problems became the bike owner's. We aren't governed by those criteria; why wouldn't we do it better, especially when the fix isn't complicated?

Hth.

Regards,