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Morning,
Forgive my lack of mechanical knowledge, but I have a simple SU carb question. Basically, how hard is to change the needle on an SU?
I had the HIF44 carb of my Metro Turbo rebuilt a number of years ago for an article in the original Retro Cars and the job entailed a high-boost needle and stiffer spring. It obviously needs setting up properly but with it having no MoT etc, I just want to get the thing running okayish so I can get it back on the road. I put on another ‘good’ standard carb from a specialist but I reckon the float’s goosed, so that’s why I want to go back to the original as I’ve still got the needle/spring that was removed from it.
Any ideas?
Many thanks
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,516
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how hard is to change the needle on an SU? Easy! Unscrew the black plastic cap form the top and pull out the small piston. Undo the three screws that hold the "dashpot" on the top. Carefully pull it up. It may come up with or without the main piston to which the needle is attached. Some oil may also leak out depending on how much was in the top. If the piston has stayed in the carb body, the spring will be sat on it. Carefully lift up the piston vertically so that the needle withdraws from the jet without damage. The needle is retained with a single screw on the side of the piston. Undo this a couple of turns and then you pull the needle out. Might be stuck a little if its not been disturbed for a while. When you change it make sure that the new one sits flush with the bottom of the piston when you do the screw up. Hope that makes some sense Edit: Idle mixture is generally unaffected by the needle profile so you ought to be able to get the car fired up and idling well on any needle that is the right size for the jet. |
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Last Edit: May 4, 2010 9:08:36 GMT by Seth
Follow your dreams or you might as well be a vegetable. |
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Steve
Posted a lot
Making progress in small, easy to handle chunks of awesome
Posts: 2,028
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Should be quite simple.
Remove the dashpot by removing the 3 screws at its base at its base then it should just lift up to reveal the slide assembly. Remove that and you will see the needle is attached to the base,should be a little grub screw that holds it in.
Damm it Seth, just too quick for me ;D
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Last Edit: May 4, 2010 9:08:03 GMT by Steve
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10mpg
Club Retro Rides Member
Posts: 4,253
Club RR Member Number: 204
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Very easy, just remove the dashpot, remove the piston loosen the recessed screw on the side of the piston and the needle will drop out, drop the new needle in take a steel rule hold the edge against the bottom of the piston and align the 'step' on the bottom of the needle with the flat base of the piston nip up the retaining screw and your done.
Whooo multiple simultaneous post shock!
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Last Edit: May 4, 2010 9:12:15 GMT by 10mpg
The Internet, like all tools, if used improperly, can make a complete bo**cks of even the simplest jobs...
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spacekadett
Part of things
F*cking take that Hans Brrix!!
Posts: 818
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Quite simple. Take the dashpot off the carb and let the piston drop down. If you look around the base of the piston there is a slot head screw in it. Loosen that off and hey presto the needle comes out. If you want the spring out as well (or want to take the piston out completely to give things a clean) take the damper out and push the piston all the way up. There's a circlip on the top of the damper tube, pop that off and the piston'll slide out. HTH  |
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Mechanic's rule #1... If the car works, anything left on the floor after you finished wasn't needed in the first place  |
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You're all gents! Thank you very much.
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