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MG Midget and Sprite Technical - What does this 'thingy' do?

Hi, sorry for the size of the photo.

This is a photo of a LZX1389 carb. piston damper, does anyone know what the purpose of the small bent metal spider shaped 'thingy' on the rod between the cap and the top of the piston valve is please?

Its to go onto an HIF44 and appears to tightly fit down the end of the piston tube and stops the piston rising up fully.

I could cut 3-4mm more off the carb. piston tube or just cut 'the thingy' off

Will it be a problem if removed?

Thanks Tony

Tony G

I have a theory/folk memory that the spider thingy is designed to stop the piston jumping right out of the carb if/when it backfires.

Not sure if this helps you but I think I only ever noticed it on Turbo Metros, there isn't one on my plain vanilla HIF44.
Bill1

Check that part number, sounds more like a ZS number. Hate it when they change numbers systems, but a ZS one doesn't fit. They had those, never sure why, but they didn't restrict movement, and they shouldn't on SU either. Just made it a PITA to put oil in. The retainer is supposed to be pushed into the top of the tube, a matter of a thin screwdriver as you put it in. At least on ZS, it does not restrict movement even if it is not correctly installed.
Might help keep the oil from being forced out the vent on vigorously driven cars (or might make it worse!).
FRM
FR Millmore


Hi,
Correct part number (marked on the plastic cap) and removed from original packing.

If the damper is just dropped down and screwed up, the 'thingy' slots about halfway down into the tube. If pushed hard, it will go all the way down, but very difficult to remove or check or top-up dashpot oil.

Me-thinks it should be cut off - I don't back-fire!

Regards, Tony
Tony G

Thinking again, it can't stop something happening which doesnt anyway. The piston cant jump out of the carb, though the damper might if the screw thread is begggarred

I remember it

but omly vaguely :(

I see on one of the SU carb sales sites that there's no clip attached to the example shown so I would take it off
Bill1

Are the three prong bits perhaps supposed to clip into the groove on the underside of the black plastic cap? But I still wouldn't know what its function was!
Guy Weller

I would suggest its the wrong part send it back and get the correct one and don't worry about what the spring does. Attached diagram of 44 which does not have the spring thingy on it.
Ed

Ed H

All, the thingy is a retainer for the damper and, as Tony mentions, it pushes in to the end of the piston tube. The HIF's on a V8 also has these but as to their purpose (other than preventing the plunger being removed and damaged inadvertently) I know not.
Yes they do prevent oil flowing in to the piston tube and the manual says to put some oil in and then move the damper down to allow it to flow in to the tube. Then repeat until the oil is at the correct level eg just above the dash pot tube at rest.

MGmike
M McAndrew

Just guessing wildly....but would it hold an O ring by chance

Prop
Prop and the Blackhole Midget

Thanks for comments,

I think the carb. diagram is not an HIF44 but an HS6, mine has a larger piston spring and originally had a high top damper (LZX 1511).
The new damper LZX1389 (with the spring 'thingy' removed works just the same, but gives better bonnet clearance.
No ill effects after its removal.

Tony
Tony G

This thread was discussed between 20/07/2012 and 22/07/2012

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