S.U.Carb choke

[marktheherald]

I have the 1500 spit engine with twin S.U.'s. One of the chokes is sticking down when the cable is pushed back in, which means I have to push the offending item back up manually. The piston is dropping correctly, I have oiled all moving parts/return springs, so far with no effect. The return springs are correctly positioned.    Any suggestions?

[Beans]

Did you check the jet-assembly itself for wear, free movement etc.?

[Nick Jones]

Assuming the rotary mechanism on the carb body is free moving and the spring is properly positioned, you need to take a careful look at the way the link rod and the little bracket where it screws onto the base of the jet are positioned.  It is possible to position the bracket the wrong way round/upside down which can screw things up.  It is also sometimes necessary to bend the the link (just a tiny bit) so it's not putting any side load on the jet as this always causes it to stick.  For a simple mechanism it can be tricky to get working smoothly.

Nick

[Pete Lewis]

some replacement jets have a too long fuel tube this seems to jam the jet return  solution after doing Nick suggestion first is  shortening the tube  by 3mm   Pete

[2Toledos]

Nick_Jones wrote:

... so it's not putting any side load on the jet as this always causes it to stick.

Pretty much along the same lines: Make sure the jet tube is sliding in a dead straight plane, and if it is; then it's possible there's a 'foreign body' in there. It'll only need the tiniest bit of 'grit' (eg speck of rust from the fuel tank) to stop it returning !.... do you have an in-line fuel filter ?

[marktheherald]

Sorry not to have put any of your suggestions to good use yet, the choke cable has snapped! Located a replacement inner cable at Leatherhead, but not yet fitted. In the mean time I have been running the car on its LPG conversion and it starts quite happily without choke. Because of the LPG set-up, I will have to strip the carb off the manifold to effect repairs. I will post results as soon as I sort it out.  Many thanks to all.  

[phards]

Mine does / did that too.  I think I was pulling the choke out too far.  When I pull it out the minimum to get the car started (and use it regularly) I don't have problems ... touch wood!
Just a thought.
Paul.

[marktheherald]

Found time to investigate the choke at the weekend and discovered the link rod/wire had bent, so had full choke even when cable was pushed home. I have disconnected the offending choke until I can obtain two of the tiny retaining clips that hold the link in place. I also note that on one of my spare HS4 carbs, the link is more substantial, being a pressed/formed item. I might look to change to two of those, as i can't see them bending so easily.