Hello
Build together a M22 engine from 1938 that has been disassembled for many years and wonder if it will be a spacer between the main bearings on the crankshaft on the drive side that later M20?
If there should be a spacer, it is someone who knows how long it will be?
In that case it must be shorter than later M20

Hi, think this looks like the crosssection of an early M type bottom end.



So it is the same construction as the later types: crankshaft clamped to the outer ball bearing. But like you say a shorter bush. Also notice the spacer on the outer ring. So the length of the bush on the shaft should have the same length as the outer spacer plus the circlip.

You also can work out the length by making sure the flywheels/conrod are in the middle of the crankcase when the crankshaft nut is fully on.

Good luck, Michiel / NL

In regard to the other topic about the oil valves:

Notice Mr. Page didn't find it necessary to add the ball valve at the bottom of the oilpump in the first place. Which seems logic because it works in the return line and the return line will never drain the oiltank.

Maybe there was some leakage from the supply set of gears to the return set ??

Cheers, Michiel

Michiel, thanks for the good and fast answer

[' Notice Mr. Page didn't find it necessary to add the ball valve at the bottom of the oilpump in the first place. Which seems logic because it works in the return line and the return line will never drain the oiltank.']

Between the return gears of the pump and the open end of the return pipe in the oil tank would remain full of oil when the engine stopped...

Maybe the ball was to stop this draining back through the return gears to the sump...Ian

email (option): ian@wright52.plus.com

Hi Ian,

Yes, it probably is, but seems to me a relatively small amount of oil to be worried about.......

an additional reason could be that it keeps the pump filled with oil while standing.

Or maybe it is only there to calm down the rider who looks in the oiltank right after starting the bike and sees no oil coming for the first few seconds..... (the early bikes didn't have the felt filter fitted over the return pipe in the oiltank so a check in the oiltank to see if it pump works was quickly made).

To be sure about the lack off a ball valve in the early engines, I just opened the oilpump cover from my '38 engine, no ball valve, just a short tube, sawn off at an angle.


(Also notice the sharp edged flywheel oil scraper, never saw that on the later engines...)

---

Just thought about another 'çould be' reason for the presence of the ballvalve: in the OHV engines it also should keep the oilpipe to the rockers full of oil, so the lubrication of the rockers starts sooner.

Cheers, Michiel

It good to know that the BSA engineers in the thirties were -as you say- trying to calm down the rider who was looking in his oil tank after starting the bike, hahaha !

Hi Michael,

Yes, it was only given as a suggestion but I admit I did let me go a bit on that point, cheers.

Think the answer is given in the meantime in the 'real' topic about the oil valves.

There is stated that gearpumps need to be primed for good functioning, so it looks to me that this bottom valve is mainly there to keep the return set of gears primed......

.....and has has no function in preventing a 'wet sump' from standing. (except for that little bit of oil that is in the return pipes)

Hi Michiel..I think the reasoning in your last post is probably correct...and I think your point about the oil feed to the rockers on OHV engines sounds logical as well..

Regarding keeping riders 'calm'..Ariel deleted the oil pressure gauges in the petrol tank because of riders with new bikes worrying that the oil pressure was too low when there was nothing wrong with it...

At tickover on a hot engine the oil pressure can drop to surprisingly, and worryingly low levels.. ....

One partly unrelated observation was how much low speed oil pressure was improved on my Mk2 Ariel Square Four after I fitted an oil cooler..!...Ian

email (option): ian@wright52.plus.com

Thanks for you back up, Ian.

Now you mentioned Ariel, BSA also dropped the gauges in their tanks in favour of the simple "pressure - or not" oil indicator button at 1937. Most likely for the same reason then......

Or it has something to do with the introduction of the new Page line with the mazac oil-pump instead of the earlier brass ones, or simply a 'cost cut down" questions, questions...



By the way, for the person who is looking for one, these indicators are the same as fitted to the Austin 7. (at least dimesionally, not sure about the internals but can't be much more than a stronger/weaker spring I think)

Cheers, Michiel

I read in a magazine article many years ago that it was the unfounded fears of owners that prompted Ariel to delete the gauges...

I guess dealers were wasting too much time explaining it all to their customers...Ian

email (option): ian@wright52.plus.com

Hello,

I have my M22 engine in bits. I can check dimensions of this spacer if still needed. (I hope I have it)

email (option): kalle.tikas@gmail.com

Hello

Here are the results:

inner spacer is 7.2mm thick ID is 25mm and OD is 33.3mm
outer spacer is 4.8mm thick ID 54mm and OD is 61.7mm
clip thickness is 1.65mm

Measured with vernier so +/- 0.05 is possible

email (option): kalle.tikas@gmail.com