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Float chamber to jet sealing?


1969Mk3Spitfire
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Been for a drive today and had to pull-over to investigate a petrol smell.  Car has run well since last summer and has done around 100 miles only this season.The rear float chamber bottom seal to jet pipe was leaking.  I managed to improve it at the roadside and limp home.

At home I removed the jet pipe, nut, washer and o ring and all look ok.  I pushed the o ring back in place, pushed and held the nut up the pipe, pushed the washer over the pipe end and re-installed.  I've read that "the more you tighten the nut, the more its guaranteed to leak" so its quarter turn beyond hand tight. I did not remove the jet.

I can't now make it seal.

Regarding what may have caused the leak, don't know if it's relevant but the rear float chamber seems to have more rubber compliance than the forward chamber.

Any helpful hints and tips to form a seal?

Thanks in anticipation.

.......car is Mk3 Spitfire with original twin SUs.

 

 

 

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make sure there is not an old previous rubber olive stuck in the chamber

you must fit the pipe nut its washer then the rubber olive and insert as  a assembly

always have a few mm of pipe protruding beyond the olive/0 ring nasty thingy.

the nut needs to be a hand tight nip to compress the 0 ring and seat and seal it 

trying to poke the pipe into the 0 ring/olive with it already in the float chamber hole will certainly leak 

Pete

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23 hours ago, Pete Lewis said:

make sure there is not an old previous rubber olive stuck in the chamber

you must fit the pipe nut its washer then the rubber olive and insert as  a assembly

always have a few mm of pipe protruding beyond the olive/0 ring nasty thingy.

the nut needs to be a hand tight nip to compress the 0 ring and seat and seal it 

trying to poke the pipe into the 0 ring/olive with it already in the float chamber hole will certainly leak 

Pete

Thanks, Pete,

I replaced the o ring this morning. A fiddly job but there now appears to be a dry seal after a 10 mile run out.

My main concern now is to try to understand what caused it to leak? There’s nothing obvious amiss. I don’t like the concept of “hand tight” and I’m concerned that if it’s leaked once, what’s to stop it leaking again.

I’d like to understand why it leaked and what I can do to ensure that it doesn’t do it again. Any suggestions?

Appreciate your help and advice.

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trouble is i have a hate of SU's  much more a Stromberg fan  (and i have a 2000 with 2 HS4 on it Ha )

as for why  chicken and egg syndrome  

as you have found its a very small squidgy olive /0 ring  if the tube was never fully thro the ring then no matter how tight it will tend to leak

theres a lot of myths about the basics but if you have fully entered the tube thro the olive and nipped it up it will be fine 

done t worry about it , iif it leaks you will get a whiff and if it helps  petrol will not ignite from a hot exhaust

brake fluid will burst into flames  

Pete

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