Oil Pressure

[mark.scott]

Hi - Just putting my 36 RH back together after a mag/dyno refurb. Since I've had the bike there has been no oil pressure registered on the oil gauge which I understand isn't a problem as long as there's oil returning into the tank through the return pipe - which it does. But it would be nice to see some pressure on the gauge. Is this something to do with a regulator at the bottom of the timing case ? Also I'd like to tidy up some of the 'plumbing' where can I buy supplies of the narrow bore copper is this a tricky job, how is the pipe bent flanged etc, does it require special tools ? Hope this makes sense and thanks in advance for any responses.

[Keith.owen]

Hi,
Oil pressure should be at about 15psi when the engine and oil are warm.

The pressure gauge indicates the pressure to the rockers and the pressure to the big end should be greater. Basically the ball valve acts as a bypass so if the pressure is too high to the rockers the big end could be starved of oil.

I would imagine that some oil is finding its way to the rockers otherwise I think you'd pretty soon know about it, so, probably either the feed to the pressure gauge is blocked or the gauge is not indicating.

To make pipes you just need to be handy at soldering, however, the feed to the pressure gauge requires thin bore pipe and special fittings - best buy from drags.

Keith

[simon.holyfield]

https://www.completeautomobilist.com/

I've bought fittings and tube from this outfit

[ian.scott]

Hi,
Oil pressure should be at about 15psi when the engine and oil are warm.

The pressure gauge indicates the pressure to the rockers and the pressure to the big end should be greater. Basically the ball valve acts as a bypass so if the pressure is too high to the rockers the big end could be starved of oil.

I would imagine that some oil is finding its way to the rockers otherwise I think you'd pretty soon know about it, so, probably either the feed to the pressure gauge is blocked or the gauge is not indicating.

To make pipes you just need to be handy at soldering, however, the feed to the pressure gauge requires thin bore pipe and special fittings - best buy from drags.

Keith

I think the book quotes 10-12 psi and on a 36 there is no feed to the (open) rockers only grease nipples.

Ian

[mark.scott]

my bike has enclosed rockers along with the grease nipples, not sure if they are being fed oil I'll check this evening - maybe this is a later mod.

[alan.moore]

Mark

If you are a AOMCC member you can download a copy of the Ariel manual for your bike (there is a 1934 and 1936 and a 1933 to 1937) from the owners club wesite document repository. Page 7 explains the operation of the gauge and regulator. According to this altering the adjustment of the regulator at the bottom front of the case only alters the reading on the guage and does not alter the pressure in the main system, so that would tend to say that any adjustment will not effect the supply to the big end ?. It says set it to give a 'normal' reading of 10-15 psi, screwing in increases the gauge reading. The 1938 manaul appears to say that at tickover the reading will be about 5 psi.

As an aside...Interestingly the 1938 manual also includes a para explaining that if the rocker clearance is too wide this can reduce the oil pressure due to oil escaping between ball end of rocker and pushrod cup. Mine is a 1939 and whilst there is a dimple in the ball end there is no hole through into the rocker spindle. This paragraph is not in any previous years or the 1939 manaul. So did the 1938 model have a feed to the rocker ball end ?

[alan.moore]

Mark:
Regarding making the pipes I made a rocker feed for my Triumph from 4.5mm 22 swg tube (which gives about a 3mm internal bore). I found that as long as you anneal the pipe well (heat it up to cherry red and let it cool down) it will bend easily without kinking or creasing at the bend. Soldering the fittings is a case of fitting the pipe into the union (both pre-cleaned) well fluxed and then heating with a small blowlamp and feeding solder in which will flow into the joint. Make sure you only use the least amount of solder you can as it can flow into the open end of the pipe and block it. So check everything is clear before fitting.

The fitting for my 1939 Ariel feed pipe (which screws into the timing case) has a feed hole just under 2mm, the original pipe outer Dia is 4.5 mm. So the 4.5mm 22 swg should work fine. I was surprised at the small dia of the feed hole but it is obviously works fine.

[paul.jameson]

Take the regulator apart and clean it very carefully. It acts as a second ball valve on the feed side so it sounds to me as if you may have a piece of dirt under the ball. After the regulator was abandoned (during the war, from memory) a second ball valve went into the of the quill which feeds the oil to the flywheels. Some genius, probably from BSA, abandoned the second ball valve in 1954 or 1955. So by 1957 we have secondary ball valves on both feed and return.

The same principle applies to the 1937-48 cast iron Square Fours. I have had mine be reluctant to show pressure (much more than usual) and found a dirty ball on the feed side of the pump. But the oil regulator saved the engine.

[mark.scott]

Hi All thanks for the info. I'll try all suggestions and let you know how I get on. Thanks Mark

[ian.scott]

Mark

If you are a AOMCC member you can download a copy of the Ariel manual for your bike (there is a 1934 and 1936 and a 1933 to 1937) from the owners club wesite document repository. Page 7 explains the operation of the gauge and regulator. According to this altering the adjustment of the regulator at the bottom front of the case only alters the reading on the guage and does not alter the pressure in the main system, so that would tend to say that any adjustment will not effect the supply to the big end ?. It says set it to give a 'normal' reading of 10-15 psi, screwing in increases the gauge reading. The 1938 manaul appears to say that at tickover the reading will be about 5 psi.

I'm sorry but that makes no sense at all.
What is the point of a gauge if it only shows the pressure you have set it to and adjustment does not affect the pressure to the big end?
Ian