Carb trumpets

PostPost by: danbuoy1 » Thu Mar 03, 2022 2:29 pm

Again - many thanks for all replies and help.

I'm thinking I've been a bit naive in just assuming they would come apart and just clean and replace jets and gaskets and the one trumpet I've messed up. Most of what I've seen so far is corrosion between steel trumpets and aly and lots of gungy bits. I'll take one apart and look closely - I'll get some photos to bore you as well.

See a set of new is around £800...

Cheers

Paul
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PostPost by: smo17003 » Thu Mar 03, 2022 3:26 pm

18 months ago I used Paul at Weber Carb Reconditioning Services Ltd. to overhaul a pair of very poor condition 40's. Cost was less than £500.00 for the pair. £150.00 for each rebuild plus new chokes, jets, etc. I've still to run them on an engine, but the service and communication was excellent.

weber-carbs.co.uk
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PostPost by: danbuoy1 » Thu Mar 03, 2022 8:06 pm

Tried to strip one of the carbs and took some photos. Most of the corrosion is where the trumpets fitted, is this aproblem if I clean it up? Managed to get the jets out altho one needed eeziout as top flange broke! Haven't touched the butterfly spindle - tried to remove an end cap using circlip pliers but not moving. The one bit that also look seized is the accelerator pump as it doesn't move, I'll try that tomorrow.

What you think and be honest :)

Cheers

Paul
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PostPost by: Baggy2 » Thu Mar 03, 2022 8:12 pm

+1 for weber-carbs.co.uk
They cleaned and overhauled my carbs around 18 months ago with good results.
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PostPost by: danbuoy1 » Thu Mar 03, 2022 8:37 pm

Cheers Baggy, how bad were yours beforehand? I prefer doing it myself, mostly as its fun but realise experience does count in the long run. I just didn't expect so much seizure on this car, I guess sitting under a tarp for 30yrs moisture has always been there....

Cheers

Paul
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PostPost by: Baggy2 » Thu Mar 03, 2022 10:20 pm

Hi Paul
To be fair I dont think mine were as bad as yours look. The car had been standing for a while in a dry-ish garage but the fuel had turned to toffee and there was no way that I was going to be able to clean that out of all the internal passages etc so sending them to a proffessional for a reasonable price seemed a 'no brainer'. They came back after about two weeks looking great , were installed on the car and worked perfectly with only normal setting up adjustments.
Hope this helps
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PostPost by: danbuoy1 » Thu Mar 03, 2022 10:46 pm

Thanks Baggy, all different I guess, glad yours went ok. I did a couple of Stroms last year and they were a relative breeze, this is almost like wading through araldite, everything is solid. I suspect they are beyond repair but I don't give up, I'll see if I can get the rest of bits out first. Just feel if its all this bad then I may walk away :(

Cheers

Paul
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PostPost by: 512BB » Fri Mar 04, 2022 8:20 am

2 cams wrote 'The only parts integral to the body subject to wear and not replaceable are the two bronze bushes supporting the throttle shaft at it's center and also where the spring clip for the auxiliary venturies contacts the body. If that clip is not in good condition the venturies will be loose and you'll get a fuel leak and improper suction of fuel through the venturi. They only become not rebuildable if damage is due to corrosion or physical impact.

I'll accept the "throw them away" argument only if people can nominate the specific problem that makes them not worth rebuilding'

Well the reasons that I rarely send carburettors for rebuild are that the two bronze bushes supporting the throttle shaft are worn and non replaceable and because old carbs are very often corroded. Are they good enough reasons for you?

2 cams also wrote 'On the other hand please keep throwing them away because I'll gladly take them!!!'

I have already told you, I do not have any more, because the mugs on ebay have bought all I had, and I thank them for paying a high price. As I sold them all in the 'FOR PARTS ONLY' category, I hope they found some of the parts useful.

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PostPost by: 2cams70 » Fri Mar 04, 2022 10:35 am

512BB wrote:Well the reasons that I rarely send carburettors for rebuild are that the two bronze bushes supporting the throttle shaft are worn and non replaceable and because old carbs are very often corroded. Are they good enough reasons for you


Like I said originally - the bushes are obviously a wear item but I've yet to see a carb where the wear is to an extent where it would cause problems. Wear on mine is around 0.0007" and that's after around 180,000km. Severe corrosion will kill a carb of course. There was zero corrosion in my carbs but it had only ever run on good old fashioned leaded super Petrol before it was laid up.

To the original poster. From what I can see in the pictures the dirt and muck on your carbs is just superficial. They will clean up just fine. After a complete dismantle, removal of the throttle shafts, removal of the lower fuel gallery lead blanking plugs for cleaning access (highly recommended) followed by a clean in solvent, an ultrasonic clean and then finally a hydro-blast they will come up looking like new.

I noticed in your previous posting that you talked about putting some prongs in the two holes of the throttle shaft bearing retaining caps and twisting them out. This procedure also seems to be mentioned a lot in Youtube videos and books (non-weber issued ones that is). Don't do this. It's rubbish information. Once you have removed the spindle nuts and the throttle valves it is only necessary to tap each end of the shaft in turn with a PLASTIC hammer. This will force the bearing against the retainer and both the bearing and retainer will come out together as a unit. This is the procedure according to the factory issued Weber manual and is the correct one to use. If the bearings are corroded in you may need some heat to assist. Mine came out very easily.

Pictures of my carbs after hydro blasting attached. Note it's well worth getting yourself an ultrasonic cleaner. The Chinese ones aren't that expensive and work fine. Very useful for cleaning bits and bobs generally - not just carbs.

The tricky parts of carb rebuilding are removal and replacement of the throttle shafts and removal and replacement of the lower gallery lead plugs (these parts of the rebuild require a bit of feel and intuition). The rest is straightforward.
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PostPost by: Craven » Fri Mar 04, 2022 12:18 pm

I understand the recommended method of spindle removal includes replacing the throttle plates space with suitable size and thickness packing otherwise as sure as egg are egg the spindle will distort or kink at this weak point, particularly when light tap increases as tight bearings won’t move.
Also very important that the correct throttle retaining screws are used as the originals are staked after final adjustment. Of course there will always be times when luck comes into play.
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PostPost by: 2cams70 » Fri Mar 04, 2022 12:41 pm

Craven wrote:I understand the recommended method of spindle removal includes replacing the throttle plates space with suitable size and thickness packing otherwise as sure as egg are egg the spindle will distort or kink at this weak point, particularly when light tap increases as tight bearings won’t move.
Also very important that the correct throttle retaining screws are used as the originals are staked after final adjustment. Of course there will always be times when luck comes into play.


I used these retaining screws from Eurocarb. They are excellent. Brass like original (not plated steel as most are), drilled down the centre at the end of the thread like original (most aren't), The chamfer is the correct angle and diameter like original (most aren't), The head is torx rather than flat blade (an improvement on original)

https://www.dellorto.co.uk/shop/dellort ... fly-screw/

Having the drilling down the centre enables these screws to be peened in the same way as original. I've found if you use a small Roberts head driver (square tip) you can replicate the way the factory did it. They didn't just bash the end of the screws with a flat punch.

I reckon you'd have to be bashing the steel shaft pretty hard to splay it near the throttle plate location. If it were me and things were that hard I'd just factor in replacing the shaft and removing it any way I could. They came out very easily using the Weber recommended method in my case.
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PostPost by: Craven » Fri Mar 04, 2022 1:40 pm

It’s the slots in the spindle that can suffer, the brass one’s are really very weak in this area.
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PostPost by: 2cams70 » Fri Mar 04, 2022 1:50 pm

Craven wrote:It’s the slots in the spindle that can suffer, the brass one’s are really very weak in this area.
Weber .JPG


The steel ones are reasonably robust by comparison. All the DCOE 31's I've seen had steel shafts. Weber obviously made some improvements over time.
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PostPost by: Craven » Fri Mar 04, 2022 1:58 pm

These are general comments and tips on this topic not specific to your particular case.
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PostPost by: danbuoy1 » Fri Mar 04, 2022 7:09 pm

Thats really good advice, thanks to everyone. Cams270 you're right, was watching a youtube and thought the end washers were threaded, now I understand just push out. Also great advice on supporting the weakened shaft when knocking it out, I wouldn't have thought of it - your pictures put my sad parts to shame!

A friend lent me an old Haynes DCOE overhaul book so will have a look through to get some ideas. Apart from corrosion he didn't think it was that bad, but he hasn't spent hours getting simple parts out! He also recommended dunking the carbs in penetrating fluid for a week, TBH apart from PlusGas never found it works but what are the views?

Going to remove Engine cam cover as well just to see what it looks like, hoping it will still have some oil after 30yrs to preserve it else worried the head will have suffered same.

Cheers

Paul
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