3 replies to this topic

[mikemate]

I have a set of hs2 carbs I've rebuilt but can't get the jets to center up.. The just keep catching on the needles and the plunger won't go up and down..
Need to know how to get them to center up

[dklawson]

The following may echo what you have already been doing so don't take offense if it seems obvious.  Before going through the basics, I have a questions.

 

Are you sure all the parts of your carbs belong together?  Later carbs switched to the swinging needle and used a different piston to support the needle.  Those carbs had little to no lateral motion possible for the jet because the needle could move.  If you mix an early fixed needle piston with a later carb body I doubt you can get the jet to center unless you are very lucky.

 

Refer to the image in the first post at the thread linked below.  The image shows the jet bushing parts.  I am sorry... the image lacks callouts for several key components.  Item #16 is a thrust washer that must be located between the jet bush #15 and the nut that secures it, #17.  

http://www.mgexp.com...d.php?1,1415954

 

Assuming your carbs do not have a mix of early and late parts... and that you are dealing with fixed needles, you need to undo all the linkages so the carbs are independent of each other.  Also remove the plastic dashpot plugs from the top of the carbs.  On the bottom of the carb body are two "nuts" #17 and #13.  Tighten #13 (up, into the carb body) which will lift the jet.  Stop when the top of the jet is flush with the flat surface (bridge) inside the carb throat.  Now look at the carb piston.  The shoulder of the needle should be flush with the bottom surface of the piston.  If necessary, loosen the grub screw holding the needle in the piston and pull/push it into the piston until the needle shoulder is flush and re-tighten the grub screw.

 

With that done, loosen nut #17.  That will relieve pressure on the thrust washer #16 so the jet bush #15 can move laterally.  You want to loosen #17 and then tighten it "finger tight".  Now reach into the carb throat and lift the piston with your finger.  When the piston is at the top of its travel, drop the piston.  It should drop rapidly to the flat bridge in the carb throat and land with a "click".  Lift and drop it several times, over and over again until you get the "click".  Once you have the "click" tighten #17 a bit while the piston is resting on the bridge.  Lift the piston and drop it again.  It should still land with a click.  If it does not, loosen #17 and try again.  When the piston repeatedly lands with a click, tighten #17 a bit more.  Keep doing this over and over until the piston falls freely and lands with a click and #17 is reasonably tight.

[mikemate]

Thanks mate you're a legend I'll use your help today and let you know how it goes,

As for all the parts being matching, as far as I know they are as they came off a running car, I've just rebuilt them using the kit and cleaned everything up

I'll keep you posted! 👍

[mikemate]

The carbs are sorted! All move freely! All go with a clunk! Choke all moves freely thanks mate! Wouldn't have done it without you