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MG Midget and Sprite Technical - Odd one out?

Photo shows the bits for the oil pressure gauge feed. Except they don't fit together. So which is the wrong part?

The double ended bit came with my 1098 engine so the block end fits ok. And the newly bought little connecting pipe was listed as a 1098 part. Unless it has been 'picked' wrongly. The cone end fits, but the nut that came with it doesn't match up with where it should screw on. So which is the wrong part?
I am always perplexed with brass fittings. They have odd threads and I struggle to find spanners to fit.


GuyW

The pipe was listed as part no AHA6392, but no specification details so I don't know if the supplied tube nut is the proper item.
GuyW

Guy
That brass fitting has different threads on either end, the tapered/course thread screws into the engine. Have you tried the pipe/nut on the other end
William Revit

Quite right Willie, but only one end goes into the block. The other end has a slightly different thread and is also too big for the tube nut, or the nut is too small for the adapter. But which should I change?

I assumed that the adapter is original to this 1098 engine, but the pipe is also sold as for a 1098, so one must be wrong!
GuyW

Guy

the adaptor in the block is wrong. See image of one from my 1275 its the same as the 948. its steel and not brass. the block end has a flat face, whereas the instrument side is machined to accept the olive.


Bob Beaumont

Bob's photo shows part number CAM6431 (union, oil pressure (gauge)), photo here is at a useful angle for you, but no copper washer shown (included?) - http://www.leacyclassics.com/cam6431.html

The cone shaped nipple on the end of your pipe I guess is the same sort as the one that goes to the fuel tank (on later cars at least) which had me confused previously as someone referred to it as an olive which to me are the bit at the other end of your pipe.
Nigel Atkins

Thanks for that, both of you. Saves me having to work out what the thread is!

The brass item with the 1/2" square centre section is machined as that Leacy one, flat end to the block and inverted cone at the outer end. But just too big a diameter for the tube nut !

On another engine I have a similar square block brass union, only that has two outer connection points, both female. One straight ahead and another 90 right. Presumably for a gauge and a warning light. Doesn't help here though.

These small parts do turn out costly bought individually as postage is often more than the item price!
GuyW

Looks like the ones you have are both aftermarket ones using non Spridget instruments?? Did the engines come from a Spridget?
Bob Beaumont

One is a gold seal that came with the frogeye, but is siezed. The other, that I am using is a 1098 10CG engine.
Its hard to tell looking at that Leacy one if it is correct. In the photo it looks like botg ends are pretty well the same dimeter, just different tgreads. My square block one has an inner end which is c.3/8" (taper thread) and the outer is 7/16". The tube nut is smaller at about 5/16" across the internal minor dimension.

Hard to tell from photos but both of those look to have a similar diameter at both ends, just different threads. It would help if suppliers included a spec detail as well as a photo.

GuyW

P&P - tell me about it, especially if you have to break the order over multiple suppliers because of stock or parts quality - but that's life today two, three or more different delivery vans to your home insead of having one shop that covers it all available.

Mini Spares photo and description cover some points - "Straight union as fitted to Coopers which had a mechanical reading oil pressure gauge. This is the union that screwed into the block. The alternative is to fit the T piece (part No TP) which will take an oil switch and the oil pipe when you require an oil pressure gauge as an extra."

See side-on photo of union for threads below (is engine side tapered? and/or slightly larger?).

Leacy is sometimes good for giving sizes but as with other suppliers this may be with the alternative part for the same part number that isn't exactly the same part or size as the original factory part.

Leacy and B&G give the fibre (not copper) washer, 2K4956, that goes engine side as 3/8" ID - http://www.leacyclassics.com/2k4956.html

I'll have a look in the parts book as I'm (almost) sure(?) it used to be a copper washer.


Nigel Atkins

On my one the threads are the same. ie the adaptor will fit either way in the block. Its not a UNF thread
I would have thought the Leacy one should be fine
Bob Beaumont

That photo of your Nigel looks like it is a tapered thread, but looks coarser than mine. This is a side on view of what fits my block. And the T piece connector on the other block uses the same thread - tapered, and fine pitch.

Oh it's flipped the photo. Block side is to the right!

GuyW

And, as an aside, I have Ansteadied my clutch bleed point.

GuyW

I was going to put up a larger photo and say I thought one side looked larger than the other and also appears to be tapered (but got interrupted so here it is now and flipped for block to right).

ETA: oh, the photo comes out same size, but it is flipped


Nigel Atkins

thanks Nigel. Helpful again!

Scaling off your photo, and assuming the inner end goes into the same 3/8" tapping in the block, that thread works out at about 24tpi, tapered. Which is the same as mine on that brass fitting.

But, using the same scaling method off your photo, the outer end is about 7/16" which is also the same as the outer end of my brass fitting. So it wouldn't accept the tube nut on my little pipe. I would be no further forward with that part than with what I currently have!

I will ring the supplier of the pipe and tube nut part tomorrow and see what he can supply
GuyW

Did you not get a new nut with your pipe fitting?

Is the fibre washer on the correct side in the photo I put up?

The plot thickens -
. Union - Oil Pressure Gauge To Block (2A269 - as per parts my reprint of factory Parts Catalogue too)
. Mini Spares - "Classic mini part '2a269' - is No Longer Available. Please see new part number(s) cam6431."

https://www.morrisminorspares.com/engine-c14/ohv-engine-c16/union-oil-pressure-gauge-to-block-2a269-p830414

http://www.minispares.com/search/classic/2a269.aspx
Nigel Atkins

Yes, nut and pipe as in first photo. Part no AHA6392.

Yes, washer goes on the taper threaded side as in your photo. Or rather, as in the minispares photo.

Its just annoying that none of these suppliers give any specification details.

I will get it sorted tomorrow over the phone.
GuyW

Guy,

Your block fitting looks like an aftermarket one, fitted a few to my Morries etc.

I think I've found a solution to your problem !

Have a look at the pics - the parts are all new - I can't remember why I bought them and still fitted the original - looks like its been in the bag for years - the pic date says 23-08-04 for the copper crush washer.

Still confused by the threads though and I have 26/32, ME etc etc.

Still It can be in a jiffy bag ASAP if it pasts muster !

R.




richard b

Richard to the rescue! Yet again, I'm loosing count of the number of times he has helped me out. Many thanks, again!

From this it rather looks to me as if the brass square adapter I have is a correct and direct alternative for the hex steel one, and the confusion has arisen with the little pipe thing supplied. With the pipe not being bent as it should be, I am now wondering if it is for fitting to the gauge itself, and they have simply picked the wrong one!
GuyW

yes the nut for the gauge is smaller!! the original (correct?) adaptor does not have a tapered thread.
The original pipe for the frogeye is much longer and has a circular bend before going into a flexible rubber pipe. The 1275 has a pipe as shown in Richard's image and the flexible hose connects to it and then via a steel pipe to the gauge.
Bob Beaumont

I've just dug out my Frogeye pipe which is as Bob describes. The rubber section is quite thick but would I be foolish to use it after all these years? (Don't know the threads but it fits the 1275 oil pressure outlet).

Bill Bretherton

The rubber connector is quite robust! I still use my original. It has very thick walls and is not cracked or perished. Probably better quality than the modern rubber offerings!! Your image shows the 1275 set up with the short pipe from the block to the rubber connector. The frogeye one has a much longer pipe from the block with a circle in it to absorb vibration. It then goes to a short rubber connector then onto a metal pipe to the gauge. Either way it makes no difference!!!
Bob Beaumont

I have a length of the correct fabric reinforced hose for when I do sort out these connections. Eagle eyed would have spotted it in the 'Ansteadied' bleeder photo I posted yesterday.

After all this fussing about oil pressure pipe connections, I don't actually know if the guage itself works. It will be hard to tell as it has no needles! - that's another little task, to get the microscope out and make a couple 😁
GuyW

Yep, the straight pipe supplied and shown in my very first post on this thread fits very neatly onto the back of the gauge. They simply sent the wrong one!
Still, it was something to talk about, I suppose!
GuyW

All's well that ends well.

I thought the nut in your original photo was old rather than new with new pipe.

In case anyone needs/wants the original connector 2A269 (with parallel threads) I found this on eBay whilst looking for the copper washer size (was 3/8") -
http://www.ebay.co.uk/itm/392202977891

It's as per photo.

Second photo from MGB Hive shows AHA6392 bent pipe with inbuilt copper flare/bulge (can't think what it's called) (instead of olive?).





Nigel Atkins

No, it's definitely a new nut, and very shiny though that photo makes it look discoloured. Just reflections I think.
GuyW

>>no needles! - that's another little task, to get the microscope out and make a couple 😁<<

Dunno if it helps but you can buy watch and clock hands of any size shape and colour very cheaply on the bay of E. I've run out of small ones unfortunately but you might find something suitable there.
The hour hand always has the larger hole.
Greybeard

Nice idea, Rob. Just !ooked and very little cost gets a mixed bag of 100 so I can have a bespoke gauge! Cool.
GuyW

This thread was discussed between 14/07/2020 and 15/07/2020

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