SU spindle bushes

[MarkRado]

My carb spindles seem to have developed some play, I am looking for a rebushing service. Davis Lonsdale has retired afaik, what are the alternatives (aside from Burlens)?
Thank you

[Chris31]

Hi

The alternative is to do it yourself. It’s really quite straightforward

Obviously the carbs have to come off and be stripped

I’d recommend a complete overhaul kit not just throttle spindle bushes. New spindles, jets, gaskets etc

Burden shown you the dimensions of the press tool and from there it’s fairly easy. Burden do have full instructions on there site , but beware they do contain a huge mistake.

They say push the new bushes in until you can feel them from inside of the throttle body. DO NOT DO THIS

It will cause and air leak around the butterfly which could cause issues when trying to adjust the idle

You push them in and leave a gap between the housing and the end of the bush. Apart from that, it’s ok

Burlens will charge a fortune for this work

[mgcjag]

Here is the link to the Burlan guide http://sucarb.co.uk/technical-hd-type-c ... reassembly

[abowie]

My 2c worth?

This is not a home handyman job. The bushes need to be reamed in line to the correct specifications. This needs specialist equipment, experience and skill. If you do it at home and stuff it up you won't ever get your carbs tuned correctly.

I am a great advocate of DIY. I've restored 4 E Types myself and work part time for a company that does ground up restos on E Types. We send all our SU bodies out to get them bushed. Having the bushes reamed professionally is cheap and well worth the cost.

[christopher storey]

I agree absolutely with Andrew Bowie. To do this properly requires the stepped reamer, and without this it is highly likely that you will wreck the carb bodies . It is not a DIY job unless you are very skilled in this kind of work . What is often not understood is that the original bushes were cast into the carb body at its manufacture, (i.e. the bodies were not machined to fit the bushes ) and thus the tolerances to which you must work are minuscule

[rfs1957]

Absolutely plus 1 from me, this is a farm-out job every time.

The Burlen instructions are hopeless, as visible on Steve's mgcjag's link, I agree - but not for the reasons evoked.

The original bushes are indeed cast in, and NOT visible inside the venturi, so they require machining out - which essentilly requires a stepped / guided end-mill or a very odd reamer - and very cleverly at that, to preserve any semblance of alignment.

Maybe Andrew can get some pictures of how it's done ?

Care must be taken not to exceed length of the bush when machining so as to not break through into the carburetter venturi. The bushes can then be pushed into place until flush with the body. If break through does occur it will be necessary for the bush to be pushed through to protrude into the venturi and then milled down flush to match the shape of the venturi wall. This will ensure the throttle disc is able to give a good seal in the area close to the spindle.

Their instructions are not, however, wrong, regarding "flush with the body" - although what they mean is flush with the rebate at the bottom of the seal housings ; and they even specify what to do if you go too deep and push out the lip, which is to keep going and then re-profile the inside of the venturi.

I suspect that unless he is an expert machinist who has already done this, considering this to be a "straightforward job" means that our friend has not fully understood what it involves, nor how critical it is, and definitely not how accurate and perfectly-aligned these bushes were on a new carburettor.

The fact that poorly-aligned bushes might feel tight does not mean they are not letting air in.

The very fact that they were cast-in is a cost-cutting exercise, as they would only require line-reaming and dispensed SU from machining the two recesses prior to pressing in bushes, as Christopher points out ; this itself is a reflection of the complexity involved in the subsequent machining which is now necessary to replace cast-in bushes today.

Personally I was lucky, in that my bushes were very good ; but I found that making a stepped tool to encourage the seal assemblies to go in square was not a luxury.

[MarkRado]

Thank you for your inputs; I am afraid I still do not know where to send my carbs to for rebushing