SU jet assembly

[Andyhereford]

Everything going back together and all was going well when I went to try starting her up and noticed a leak from the jet assembly “tube” …the clear rubber tube inside the metallic gauze sheath connecting the bottom of the float chamber to the body of the carburettor.
Having taken the carburettor off there is a small hole at the carburettor end of the tube no doubt due to age and careless handling by myself.
Before ordering a new jet assembly do I also need to get a new needle?
Thanks for any advice.
Andy

[philthehill]

You do not need to get a new needle!

[Andyhereford]

Phil
Thanks for your reply

[svenedin]

Be careful when you put on the new jet tube. There is a good video on YouTube from Moss Motors showing how to do this. It can be done with the carburettor on the car but if you haven’t done it before it’s much easier with the carb on the bench.

https://youtu.be/ZPzu2zzyGCQ

Stephen

[Andyhereford]

Thanks again. Just watched the YouTube video. Very clear and helpful.

[svenedin]

Thanks again. Just watched the YouTube video. Very clear and helpful.

You're welcome. If replacing an old jet tube make sure the old O-ring is out before installing the new one. It is very difficult indeed to check this with the carburettor on the car. The video shows you why.

[Andyhereford]

A bit of a silly question but I have had quite a lot of “ two steps forward one step back or even one step forward two steps back” with my car that I would like to try to get this right first time. Have watched the video about connecting the jet assemble “tube” into the bottom of the float chamber ….I have taken the carburettor off the car…BUT to fit the jet into the carburettor body do I simply undo the two nuts / spring assembly ( the mixture adjustment mechanism?), slide the new jet into place and then retighten. If so will the needle line up with the new jet correctly? …and presumably the mixture will need readjusting if / when I manage to get it going again.
I have great fun working on the Morris. It would just be nice to reach an end point with it.
Anyway thanks for any help you can give.

[philthehill]

To fit the jet you do not have to undo the two nuts.
The old jet should just slide out and the new jet just slide in. Oil the sides of the jet to help with insertion.
If the piston drops with a nice clunk then the jet is centred and you will not have to do any more.
You may have to adjust the mixture but not too much either way as you are replacing like for like.
Good luck.
Phil

[Andyhereford]

Thanks as always for your help