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MG MGB Technical - Mystery part

I know you guys like these ones. I really wish I took more detailed photos 2 years ago when I stripped the car. Now I have got bits that I have no idea where they go!

This one is some sort of switch or trasducer I think. And I am pretty sure it goes on the oil line so I am guessing a low oil warning sensor perhaps? I put a picture up here at the bottom of the page:

http://www.asciimation.co.nz/pics/page8.html

Simon

Simon Jansen

Simon, It's used to sense oil pressure for control of the anti run-on valve. It's in the USA Moss catalog;
http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29083
See items 19 & 20. If you don't have the anti run-on valve you can remove the switch and install a plug for neater appearance.

Clifton
Clifton Gordon

Thanks Clifton. I only have the Moss UK book and that doesn't have it as far as I can find. How does it work exactly? I will leave it out since all the emissions stuff is off my car but I am curious.

Simon
Simon Jansen

Simon, Oil pressure closes the switch contacts when the engine is running. When the ignition switch is turned off 12 volts is sent to the anti run-on valve. The valve opens to shut down fuel flow through the carb jets, the engine stops running. When the engine oil pressure gets low enough for the switch contacts to open the ground feed to the anti run-on valve is opened and shuts the valve off. Paul Hunt has a more detailed description on his web site.

Clifton
Clifton Gordon

I'm baffled as to why Simon can't figure out a simple switch, if he can do this:-

http://www.asciimation.co.nz/beer/index.html

Well done Simon.

Derek Nicholson

"I'm baffled as to why Simon can't figure out a simple switch, if he can do this"

Too much beer :)

I was thinking it might make a good oil pressure loss warning device hooked to a nice bright red light on the dash near the oil pressure gauge. Have to do it through a relay or a small circuit so the light is off when the contacts are closed but that isn't tricky. A light is easier to notice than a gauge when glancing at the dash and my dash is going to be non standard anyway.
Simon Jansen

Excellent thought, Simon. Let us know when you've got it figured out. I've got a plan to put a light on the top of the dash so I don't drive for miles with the turn indicators on! My excuse? Smaller steering wheel rim completely blocks the stamdard (mini) lights on the dash. That, and old age!



Derek Nicholson

Simon, I want to know when you're going to market that beer cooler in the US! Cheers!
Jeff Schlemmer

I haven't actually run it for years now. I was halfway through rebuilding it but haven't done anything much while I have been working on the car. I guess the challenge has gone from that project once you get it running.
Simon Jansen

Hi all.

A light is good, but an audible alarm is even better.

Small alarm buzzers are very cheap these days.

Don
Don

Ive thought a bit about this too. Depending on how much pressure is required to close it, it could be wired into the ignition system to kill the car if the pressure drops for some reason, ie. loss of oil, too little oil in crankcase, etc. It would also prevent the car from starting until sufficient oil pressure has built up. I offloaded my anti-run on valve on the V8 so have been thinking I might wire it to the coil or something to kill spark. Haven't worked out all the details yet, just something else to put in as a safety measure.
Jake Voelckers

Simon

In the U.S. we have a TV show called Mythbusters, a couple of guys, that challenge various "Myths". One of their shows was on how to best quickly cool a can of beer.

Your machine would have been an interesting addition to the ways they tried.

http://dsc.discovery.com/fansites/mythbusters/episode/episode_04.html
Bruce Cunha

Hi Bruce, I have seen that show (and indeed that episode)! A friend of mine in the states knew it would appeal and he records them on his Tivo and sends them down to me on DVD. He also sends down American Hotrod (which makes me feel inadequate as a car builder) and American Hotrod.
Simon Jansen

if anybody wants to install a low pressure warning lite you should consider the old oil pressure sender for a 40 hp beetle circa 1960. It was adjustable via a small screw inthe center of the post. Normal pressure turned the light of at 6 lbs and back on around 3.5 lbs.
Sandy Sanders

So that's how they fixed the low oil pressure on those old bugs! LOL
Tom

Simon<some great pic,and GREAT workmenship.Great job on the rear lite patches.Did you "fab" them yourself?What procedure did you use.Rich O
rich osterhout

Rich, do you mean the little pods under the tail lights? Those I bought as a spare part from Moss. They are commpnly used when converting from RB to CBs.
Simon Jansen

That switch looks like the oil pressure switch for the anti-runon valve, but note it operates the *reverse* way to a 'normal' oil pressure failure switch that lights a warning lamp. The MGB item *closeds* when it has oil pressure, and *opens* when it does not. In conjunction with a special contact on the ignition switch this ensures the valve operates when the ignition switch is turned off with a running engine, and releases it again as soon as the engine has stopped and the oil pressure died away.
Paul Hunt 2

Simon,I was refering to what "Lindsay Porter"(in his book,page 45)calls the "hull" beneath the rear lights.Is that a Moss part?or did you fab that part.What are you speaking of when you say "converting from RB to CB? Thanks, Rich O
rich osterhout

This thread was discussed between 29/01/2006 and 08/02/2006

MG MGB Technical index

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