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MG Midget and Sprite Technical - valve train lubrication

I got my 79 (1500) midget about 3 months ago. The radiator had been mickey-moused (incorrect radiator) and was leaking. Yesterday I finished installing the new radiator, exp.tank, etc and started the engine. the red dash light came on. I incorrectly assumed that it indicated lack of oil pressure. I now know it is alternator, not oil, but anyway: I checked the oil pressure. It is 40-60 psi depending on engine rpm. the level is perfect, the filter is new. I blew nitrogen into the oil pressure port, observed flow from the rocker arm oil bleed holes. But when the engine is running, there is no oil flow from these holes. Where should I go from here?
M S Powell

Hi MS, I think you need more pressure to get this flow and I think the rocker cover probably needs to be on to get it.
If there is plenty of oil up there then it must be working as its the only way for oil to be fed into the rocker arms and box on a 1500.
Dave Squire (1500)

It's almost dry up there. that's what scares me. somewhere, I think in the Haynes manual, I read "oil is fed to the valve gear via the hollow rocker shaft at a reduced pressure by means of a scroll and two flats on the camshaft rear journal". Does this constitute some crazy kind of "secondary" oil pump? Or something else?
M S Powell

there are some John Twist of University Motors videos that include very useful information on the 1500 engine that may tell you what want to know or help (include the 1500 engine oil path)

plus they will help with other matters, many may not be specifically about Spridgets or 1500s but on most of the videos the general principles also apply – http://www.youtube.com/user/Universitymotorsltd#g/u
Nigel Atkins

I think this vid might help (not viewed it again though) and there are others - http://www.youtube.com/watch?v=uAgbcbxFD98
Nigel Atkins

I have a vague memory of modifications being recommended for the 1500 engines to increase the oil flow to the valve train. You might try some keyword searches in the archives. I think Deborah Evans (not sure of my spelling) had some details about it, and I believe she is well respected for building up the 1500s. If I spelled it right, you might be able to search her name in the archives.

Charley
C R Huff

If its dry up there then the oil feed is definitely blocked or the oil pressure very low. On normal road going use engines the oil feed is adequate to good. Its only when you start to mod up that it becomes inadequate. Debs explains about external oil feeds as on earlier triumph engines but warns about the significant down sides in the same breath unless other mods are undertaken so be warned.

It sounds like you need to start by taking off the rocker shaft and looking at where the oil feeds up the pedestal to see if that has oil in it. On mine a pool forms when I remove the rocker gear about 3/4 of an inch across. If there is oil there then the problem must be in the shaft somewhere. If not then it sounds like the oil way to the shaft is blocked.

The oil way through the head is not straight but you can probe down the oil way till level with the bolt in the cack corner of the head which is a plug for the machining that brings the oil way over towards the edge of the head and block. Unfortunately the only way to check lower down is to remove the head due to this 'bend' in the oil way.

If you want to read what debs said someone posted a link in a thread of mine referring to rocker oil as I was not sure at the time how it got there. This was a few months ago.
Dave Squire (1500)

Just been doing my valve clearance and this is what my oil looks like. (see pic). The valve gear has been off for a re torque of the head and so has been un oiled for approx. 15 hours. My oil light will go out after about 3 or 4 turns of the engine max. Whenever I take off the rocker cover it is always well oiled (shiny with a layer of oil) but not 'running off'.



Dave Squire (1500)

This thread was discussed between 09/06/2013 and 13/06/2013

MG Midget and Sprite Technical index

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