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MG Midget and Sprite Technical - Spark arrester

Spark arrester - presumably does what it says on the tin (capsule) But why do some cars have them and some don't? Or is it just that most owners jettison them?

I have one for my Frog. I don't know if it works or not. The only thing I can do to test it is to blow through the thin pipe. It is clear, if I blow quite hard, but is this a good thing or a bad thing?
I have no idea what actually lurks inside the in-line pod. A small poloiceman waiting to arrest any bright spark that strays up the pipe?
GuyW

guy, was not aware the frog had a spark arrester. (i'll come quietly guv). Is it the chamber on the vacuum advance?
Bob Beaumont

That's what I take it as.

I think it's some sort of trap/restriction to petrol/vapour, a larger bore pipe with loop or bend(s) might be as effective, if it's required anyway.
Nigel Atkins

Yes, the spark arrester I am talking about is the little bomb shaped thing on the vacuum pipe. It is, or was, daubed with yellow paint matching the paint on the gold seal 950 engine that came with the hulk. But as that wasn't the original ex factory engine anyway, I am going to a 1098. I just wonder if I should try and use the spark arrester or just a thin vacuum pipe as is more normal, at least in later engines.

I am also curious to know what is inside the little bomb!
GuyW

A good question.

As you say, later engines didn't use them, so you have to wonder why they were there in the first place.
Dave O'Neill 2

ah ha! I know it as the vapour trap! Apparently according to my BMC Morris Minor workshop manual its to stop fuel being sucked into the diaphram! It was a standard fitment on all BMC products until the early 60's when the plastic pipe was introduced and the screw terminal on the carb and vacuum unit were changed to push on. Apparently it has a gauze filter that traps excess fuel. The HS2 carbs have a push on take off anyway.
Bob Beaumont

Bill,
I thought that was what you meant in your earlier reply.

It's not just the carb end that varies, earlier(?) ones had a union that screwed on to vacuum wotsit on the dissy and after that I think it might have been different ends to the metal pipe but I can't remember.


Guy,
you could cut it open to see, you can get new replacements, a few years I got one to try on my later engine but sent it back for why I can't remember now. Probably all in the Archives.
Nigel Atkins

This thread was discussed on 27/04/2020

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