Series 'A' Oil Pump Modification

[Marcus Bowden]

There is always a chance for any thing now a days you might be left one (a twin that is like me) but it took me over fifty years to get my single finished and complete thanks to Bill Parr, but it's creating too much oil pressure but I have increased the supply by half as much again with 3/16" wide gears and now made an adjustable relief valve, will submit a photo later.

 

[A Nut]

Well done Marcus,
I would like to see the finished oil pump at some stage. Perhaps you could do an article on it?
Brian

 

[Marcus Bowden]

Brian my handsome,, here is part of the cocked up supply pump having an insert fitted as I machined it too deep, it's ended up 3/16" wide and have so much oil pressure I can't keep it in so now made an adjustable relief valve, opened up the oil quill to 4 to 5 mm fitted a Teflon collar over it so it can cold flow into the end of the main shaft and seal producing 35 P.S.I. as the big end is a plain floating bush like a Royal Enfield (built like a gun) will show the relief v/v another time as no photo yet. Cheeper to make a bush than buy a Vincent big / end. All the 100's k hours an a ships plain bearings have never replaced one just imagine the surface area to that of a line contact of a roller and it's ability to Brinnell the crank pin.
bananaman.

 

[Marcus Bowden]

Here you are lads, you may notice that there is not a lot of hosing as I didn't have much of it (herring bone that is) as I prefer that than the plain stuff that "A's" had normally.

 

[vibrac]

Did you put a plain big end in the chain drive trials bike Marcus?

 

[Marcus Bowden]

No Tim as it felt so good and the actual usage of it was only a few thousand mikes if that, Pat Wilson built it about 1953 from back door bits of the ex-works as I remember him having a friendly argument when driving back from Rugby after the 1969 annual dinner when Vincent & HRD were present on the top table, Pat was saying how much quieter it was with the chain drive and Vincent that it wouldn't have the reliability that gears gave to the timing. As you know I have a few more Comet engines and have started modifying another set to fit the Honda oil pump but directing it's outlet into the filter housing so all the oil is filtered then fed into B/E as the works tried plain bearings on the early Flashes but the oil supply was not constant so didn't last so was abandoned. Godet racing 500's use a plain bearing. !
The new rear frame being fabricated in 1" Dia S/S as the Original rotted through after being zinc plated and chemicals got inside the tubes then left for 30 years as I've had it since 1976 found the picture of it in Jan 78 front cover of MPH as I noticed the shape of the oil tank as it was a photo Sid Biberman took in 53 or 54 when he was over visiting the works.

 

[A_HRD]

Marcus,

Reference your oil pump photos #4 above; where does the small clear pipe go to that comes from the top of the oil-pump - where there would normally be a short 3/16 BSW cheesehead screw on a standard 'A' pump.

As an aside, the Neal Videan new twins had an uprated pump too. But they apparently had no issues with it. Of course, the whole construction was focused on eliminating oil leaks completely using modern method and materials. It seems to have worked - or am I wrong again?

Peter B

 

[greg brillus]

Not quite Peter.......On the new A twins the oil pumps had much longer gears and longer housing to match........The extra oil delivery was fine engine wise, but the extra return flow to the oil tank caused leaks around the filler neck/cap.........this flow at engine speed was actually quite excesive........In the end, Neal had some smaller housings cast up and new pumps were made by the Horner brothers worshop.......These new smaller pumps are much better and the flow is now reduced........They have also changed the overall gearing of the bike to reduce engine speed, as before they were a bit under geared, moreso than the original twins. Cheers.........Greg.

 

[Marcus Bowden]

Peter, the clear plastic pipe line goes to an oil pressure gauge on the handle bars also plastic to the rockers so one can see is getting to them as well, trouble with being an engineer is wanting to know how every thing works and instrumentation is the only way exhaust temperature is next can't rely on the glow from the pipe and on a twin want to balance them as much as possible.
My bike will look like an airplane cock-pit drekly. (Cornish word meaning soon)

 

[oexing]

Marcus, the pressure setting screw on the relieve valve acts on a spring , or no ? I think there must be a spring for handling viscosity changes while the oil heats up. Is it really that much oil pumped around so the drain side cannot cope ? Modern bikes have Eaton pumps with high delivery so what´s different with these ? Maybe think over the return side into oil tank for better flow and venting ? In the photo a relieve valve from a radial engine, 45 degrees seat, plus its spring preload and setting nuts.

Vic