Rebush SU Carbs Black Magic?

[60Bugeye]

SU carburetter rebuilds seem like a fairly straightforward thing a DIY shade-tree mechanic could handle. After all, the SU carbs seem mechanically pretty simple.

In my research it seems that "re-bushing" requires professional "black magic."

Forgive my ignorance (I just got my Bugeye project ), but what does "re-bushing" really involve?

Is it THAT difficult to do?

Does it require special tools or years of experience?

Perhaps it does; just attempting to understand why.

Cheers!

 

[spritenut]

I have rebuilt many SUs over the years and have never found one that needed to be re-bushed. Most will need new throttle shafts which will be obvious as soon as you pull them out. The shafts wear in the carb body. Rarely do the bodies wear.
I am not saying the bodies do not wear, and larger throttle shafts are available for worn bodies. It is a matter of matching the new larger diameter shafts to the carbs. Any machine shop can do it or anybody with a steady hand and a good drill press can do it at home.

 

[glemon]

Excellent choice, I noticed you said you didn't know quite where to dive into the big project on another thread, they are pretty straightforward and easy to rebuild, and it is a nice job because you just take them off the car and you can do all the work on a nice table or workbench rather than on your back or whatever for some jobs.

Take one apart at a time, then you will have the other for reassembly reference.

There are prerry good exploded diagrams in the manuals, I think you had the Clymers, that is a good manual and reference for your work on the carbs and the rest of the car.

Oh, yes another reason to take one apart at a time, the pistons and top piston housings a matched sets, often doesn;t work to try to mix and match certain parts from different carbs.

 

[JPSmit]

To be completely correct (and I am pretty sure this is right) HS2 Carbs never had bushing for the shafts, HS4's did. I am fairly certain that you can now get bushings for HS2's but, mostly it refers to spritenuts description - redrilling the body for a larger shaft. there is a description somewhere on these boards (May be the MG forum). I can't usually find stuff like that.

 

[60Bugeye]

Excellent choice, I noticed you said you didn't know quite where to dive into the big project on another thread, they are pretty straightforward and easy to rebuild, and it is a nice job because you just take them off the car and you can do all the work on a nice table or workbench rather than on your back or whatever for some jobs.

Take one apart at a time, then you will have the other for reassembly reference.

There are prerry good exploded diagrams in the manuals, I think you had the Clymers, that is a good manual and reference for your work on the carbs and the rest of the car.

Oh, yes another reason to take one apart at a time, the pistons and top piston housings a matched sets, often doesn;t work to try to mix and match certain parts from different carbs.

Yep, I think this will be a good first sub-project after I go through the lot and photograph everything.

Also, I have 4 SUs and them are in a box, so will have a lot to practice with.

 

[60Bugeye]

I have rebuilt many SUs over the years and have never found one that needed to be re-bushed. Most will need new throttle shafts which will be obvious as soon as you pull them out. The shafts wear in the carb body. Rarely do the bodies wear.
I am not saying the bodies do not wear, and larger throttle shafts are available for worn bodies. It is a matter of matching the new larger diameter shafts to the carbs. Any machine shop can do it or anybody with a steady hand and a good drill press can do it at home.

Good to know that replacing bushings is not necessarily obligatory. Thanks!

 

[60Bugeye]

To be completely correct (and I am pretty sure this is right) HS2 Carbs never had bushing for the shafts, HS4's did. I am fairly certain that you can now get bushings for HS2's but, mostly it refers to spritenuts description - redrilling the body for a larger shaft. there is a description somewhere on these boards (May be the MG forum). I can't usually find stuff like that.

I think these are HS2s since they measure 1.25, so this may be a non-issue for me. Thanks!