SU reaming tool needed

[Michael Oritt]

I have H6 carbs on my 100 Le Mans and the 5/16" throttle shafts are loose. I would like to ream out the bodies and go to the oversized .320" throttle shafts. Moss wants $270.00 for the reaming tool and I do not anticipate I will need to do this job again during my lifetime. Does anyone have one of these they would be willing to loan or rent?

 

[steveg]

Why not have your carbs re-bushed with new stock shafts? Less work than oversized shafts + refitting the butterflies etc.

 

[blueskies]

Here's a link to what I did, if that helps.

https://www.britishcarforum.com/bcf...s-of-throttle-shaft-reaming&highlight=reaming

 

[Michael Oritt]

Since posting my request here and to a couple of newsgroups I have heard from several folks that usually the wear is confined to the wearing portions of the throttle shafts and before doing reaming, etc. and going to oversized shafts I should loosen the throttle plates, etc. and see if there is a shoulder on the shafts. If so that would indicate that I could probably simply replace them with new standard sized ones and eliminate all or most of the vacuum leakage. That certainly sounds like a simpler and less involved/expensive solution so once I get the carbs off I will see if that is an option.

 

[busybrit]

I've rebuild a number of carbs using new shafts. Using oversized shafts, never again. More trouble than its worth. All the parts that go on the shafts also have to be opened up, you know the parts that turn the shafts, the parts that join the shafts.
You're right about evaluating the worn shafts first, and trying new shafts, unless they are really bad, new shafts on their own have always solved the vacuum leak for me.

 

[blueskies]

I wouldn't use oversize shafts. The rebuild kits include new bushings, that allow one to use standard size shafts. If the carb body is not worn, then just using new shafts should do it.

Not sure why, but larger applications with bushings and shafts/pins often wear the same way as well. I recently rebuilt bushings and pins on an excavator and ended up mainly just replacing the pins. Most, but not all, bushings were within specs.

 

[Gary H]

The original shafts on my HD8's had too much play. I took oversize shafts and the Moss rebuild kit to an experienced Healey mechanic with a request to ream and use oversized shafts. He wisely recommend not to ream. He used the nylon bushings and original shafts which solved the problem.

 

[Michael Oritt]

All--

Due to the fine weather here in the mid-Atlantic I did not get around to removing the carburetors until yesterday when snow was forecast--and naturally did not happen.

In any case I disassembled everything this morning and--as many of you predicted--the wear appears to be confined solely to the sections of the shafts that pass through the carb bodies. There is a noticeable difference in feel when I partially withdraw the shafts so they bear on the non-bearing ends and so I am sure that standard shafts will do the trick.

Thanks as always for the good advice.