Wanted : 1928 oil pump

[Vincent.vanGinneke]

Possibly these pumps went in to malfunction after many, many years of service without getting any service themselves
It's so damn basic that not much can go wrong being the best lubricated part with fresh oil on the whole bike.

One question though, these two grooves for a O ring, does it matter if they are squared in the bottom or should they match the round O ring ?

[cmfalco]

One question though, these two grooves for a O ring, does it matter if they are squared in the bottom or should they match the round O ring ?

Although my drawing in an earlier post shows that in 1928 they made their grooves with a rounded shape, an O-ring only needs a simple square groove to seal, which is what is called for in modern designs. If I were making a new housing from scratch I'd consult the Parker O-Ring Manual to find the modern recommendation for depth and width of the grooves.

[nevhunter]

YES the "O" ring has to have somewhere to deform into or you run an increased risk of shearing a bit off the outside when you are assembling the Part. Nev

[Vincent.vanGinneke]

Thanks Charles and Nev !

[MGriffin]

Fiddling about with my initial thoughts of press re-forming an SU fuel pump copper valve disc.
It worked in principle but I’ll need to now make a paralell coil spring before trying to complete it.

[nevhunter]

Do you really know what's happening in there as you assemble it? It might be better IF the other end of the spring LOCATES on the extension of the Bolt. Nev.

[cmfalco]

It worked in principle but I’ll need to now make a paralell coil spring before trying to complete it.

The wire used for the spring in your photograph looks much too thick. The spring barely needs to do more than hold the cap against gravity since the upward motion of the plunger creates a negative pressure difference above it to hold it closed and keep oil from being sucked back the wrong direction.

[MGriffin]

It worked in principle but I’ll need to now make a paralell coil spring before trying to complete it.

The wire used for the spring in your photograph looks much too thick.

Agreed. This was one of a few springs i picked up from an odds n sods box at the springmaker who made some plunger springs for me.
Now that i have your pics and sketch I can get some much lighter paralell coil springs made up.
M.