ET: Engine (Twin) Oil Pump and Oiling Sytem Modifications

[Marcus Bowden]

Since 1990 I had done 108K miles since 1970 broken quill took me to France to have my main bearings re-sleaved by Herve' Hamond whilst there I fitted a Honda oil p/p generating 1.0 bar pressure into the cam oil gallery blanking off the cylinder supply the pressure gauge use to oscillate at low revs as the oil was shut off and on by the rotation of the cams, (will show a picture how this was achieved). The next time the engine was down was 2010 when a coil packed up and I was running twin plugs retarding the engine dramatically and holed a piston on rear pot and dropped an exhaust V/V seat on the front, all cams had less wear than when fitted between 1970 & 1990 to 2010 another 110k miles and even less wear 2018 main bearings rumbling 80k miles only a couple of thousands off the tops of the cams.
Not all spindles are made the same so if there are no oil holes under the cam face grind the surface under the case hardening and drill another hole then grind a groove around from the hole anticlockwise so oil can start flowing into cam before follower reaches cam.
First is a new spindle 2nd is the one to be fitted, 3rd is the one removed as the threaded part had snapped off due to over hardening. these are all fitted with the holes pointing upwards between the push rod tubes, which I think proves that the oil is getting to the face of the followers that are polished stellite as they have done well over 300k
any other questions please PM me email inside front cover of MPH

Honda p/p fitted and takes oil from behind the flywheel trough where there is a weir fitted so creates a oil reserve

the weir is behind the dip pipe with a hole on top tapped into the scavenge p/p suction

 

[greg brillus]

Stu, I'm not sure of the availability of any Mk 3 cams....... generally i have bought my new cams from Neal Videan here in Australia........he only supplies the stock profile Mk 1 and Mk 2 grinds........i have not had any issues with them, and even the Mk 1 type with new followers do not seem to be noisey at all........i am very weary of any Vincent cams on account of several failures I've seen........But i put most of these down to poor materials or grinding process (or lack of) in their manufacture........On the mods that Marcus carries out on the spindles....... I do a similar mod but not the spindles, i machine a radial groove within the inboard cam bush ( the one closest to the crank case) in line with the existing lobe feed hole, but also in line with the innermost hole in the cam spindle.........This increases the feed to the inner (inlet) lobe to what it should be instead of the tiny timed squirt that it receives in stock form.......how the inlet lobe and follower survive here at all is a complete mistery........Think about the "Timed squirt" that it gets as the hole in the spindle and the hole in the cam lobe line up for a fraction of a second........crazy.

 

[bmetcalf]

I machine a radial groove within the inboard cam bush ( the one closest to the crank case) in line with the existing lobe feed hole, but also in line with the innermost hole in the cam spindle

How do you do that? I am no machinist!

 

[greg brillus]

In the lathe with a tiny boring bar.......need a good torch and keen eyes to align it all up that 1/2 inch hole......

 

[Marcus Bowden]

Greg my handsome, the way you do it the oil pressure is squirting the whole way round as the cam rotates where as mine only squirts when required under the follower and the cam ramp. What pump are you using to deliver such quantity and pressure ? What pressure are you getting.
300 k miles plus is sufficiently good enough for this component, a lot better than the average wear limit I would say !
I'm now working on plain bearings or floating bushes like Royal Enfield as that is what Godet did on his TT Flash. 120 k miles is the best I've ever got out of a bottom end and replaced six in my bike where as on my ships engines I've never replaced one and they go on for hundreds of thousands of HOURS with out being touched accessional inspection only, only to inspect the bolts as they do get sticky to disassemble with shellack.

 

[bmetcalf]

Marine diesels rev a lot lower than Vin motors, though.

 

[greg brillus]

Hi Marcus, I figured the mod was no different to the outer exhaust lobe, that gets oil fed constantly via the hollow section between the bushes........trying to "Time" the oil delivery is very hit and miss with the plunger strokes of the stock pump at any rate.......My race single runs a similar pump to yours....a Suzuki DR 250 dirt bike pump that runs at the same speed as the large idler, or 1/3 rd of crank speed.......and it only feeds the cam spindle.......the stock single start pump feeds the crank only. I have no idea what the secondary pump puts out in pressure, only that when you spin it over the oil squirting out of the hole in each cam lobe is impressive.......with previous failures of cams/followers in other race engines I've had, I figures an excess of oil here could do no harm........it would appear to me that its not so much an oil issue, but poorly made or a miss match of materials used that causes premature failure here.......Cheers......Greg.

 

[Marcus Bowden]

Thank you very much Greg, I fit a second bush in at the cam end as that is where most loading is so the oil is still controlled.
The post war single stock pump will be fitted with double start as my twin is .
Thinking that I want all the oil to be filtered I've already drilled into the filter chamber from the timing cover but corresponding with a German friend he pointed out that the feedback from my Honda p/p would return the sump oil back to my oil tank, which would be correct. So the outlet from the p/p sleave must be blocked off and a non return valve fitted into the sleeve end plug (ball & spring) To do the same to a twin the oil feed to the crank pin would have to be enlarged considerably.
What I've done to my "A" Comet when fitting a floating bush Enfield style.
Floating bush with herring bone grooves taking oil out to the extremities but stopping before the edge. Pin and con-rod eye polished as much as possible with 0.002" either side of bush . Oil pressure in the region of two bar or 30 psi but having difficulty starting so fitted coil ignition now

oil p/p housing machined out to deliver half as much again, the brass is a cockup as I went too deep

Big bore quill made and fitted with a teflon seal up against the mainshaft that cold moulds into tapered end of crank

 

[greg brillus]

Interesting mods.......Is the return pump (scavenge) oversized as well.....?.......On the new "A"s of Neal and Rodney's, the oil pumps were too large........Not a big issue for the engine persay.......more the return to the oil tank was excessive like a fire hose........it was difficult to keep the oil from pushing past the tank cap seal, and oil would go all over the tank top........Smaller pumps fixed the prob.

 

[Marcus Bowden]

The return was left at 1/4"wide gear the supply was 1/8" and I made them 3/16" deep. I've now got to concentrate on the non return valve at the end of the B, C & D series p/p sleeves, progress is slow and don't get as much done nowadays spending too much time walking to keep my legs working as normally only shuffling between bench, lathe and bike bench stand with another Rapide in the garage that hasn't been touched in six years, (the first I ever saw in West Looe in 1958)