Hymn to the 1928 Model C

[cmfalco]

Vincent,

For what it's worth, a later BSA rocker from a B31/B33 looks to be essentially identical, but with a larger shaft.

Something to consider would be boring your existing rockers somewhat oversize, press fitting a cylinder of G2 or NiResist cast iron (as used for valve guides), and boring/honing to final size. Or, the same with the already-oversize BSA rockers if careful measurements show they have the correct lengths and angles.

[Vincent.vanGinneke]

Hello Charles, that is a very good tip, thanks.
These must be plentifull available.
I did find a picture showing a rocker from a Gold Star, and it looked similar but maybe longer.
I'll go and find some of these and look if I can alter them to suit.
regards, Vincent

[Karol Burger]

I tried to make new pieces, but I couldn't find a suitable pattern. When finished, the rockers were short and incorrectly seated on the valve. I decided not to give up and return to this part again. The rockers for the year 1926 - 27 work well and therefore we have to complete the ones for the year 1928 + it will be sometime in 2023

https://www.arielklub.sk/inzerat-21295- ... 7-ohv.html

[Vincent.vanGinneke]

2023 ? I try to find out if the BSA items work and if not, I get a oversize shaft made for my '28 rockers and have the rockers straightened .

[Vincent.vanGinneke]

A question just to confirm my thoughts...
The 1928 engine has a single plunger oil pump . ( '29 the double plunger was introduced)
The route the oil takes from the pump is via a channel through the crankcase wall next to the large bronze mainshaft TS bearing.
The oil then gets in a 'gutter' around the TS mainshaft.
The oil pressure -not much I guess- forces a part of the oil towards the large bush but it also gets in a small hole situated on the bottom in this gutter towards the bigend.
I assume centrifucial force is playing a role here .
The working of all this relies on the the crank assembly to stay in contact with the TS crankcase wall.
The crank assembly should not wander off to the other side, no side play.
I think I grasped it,.... this all happens because the ESA spring sits inboard of the primary sprocket on the D.S. ?

difference between 1929 and 1928 :

[Karol Burger]

Hi Vincent
in 2015, I wrote my findings on crank lubrication at the lossy Ariel. this is how I recorded it at that time

https://www.arielklub.sk/magazin-ako-fu ... riela.html

[Vincent.vanGinneke]

Thanks Karol, I've just read it and saved it.
But it does not mention the way the crank is held against the T.S. crankcase wall.
Does this happen by means of the ESA spring or am I wrong?

[cmfalco]

Vincent, somewhere in my rebuild thread on Britbike is a drawing, successfully hiding from me, that shows the region where the oil enters the crankshaft. A "nose" on the timing-side case projects into the cavity on the crankshaft, which makes end float permissible. I'll look again for that drawing and will post it here if I manage to locate it.

[Karol Burger]

Thanks Karol, I've just read it and saved it.
But it does not mention the way the crank is held against the T.S. crankcase wall.
Does this happen by means of the ESA spring or am I wrong?

exactly, the shock absorber spring will not allow the crank to move to another position

[Vincent.vanGinneke]

Thanks Karol .