Carb trumpets

PostPost by: danbuoy1 » Wed Mar 02, 2022 9:39 pm

Cill replacement on hold as sorting out space to store seats so decided to remove carbs as need to anyway to remove body at some point. Ended up removing with air box as trumpets wouldn't come out.

Ok I'm new to this (tho many years with other makes) so assumed they'd just need a little help - didn't realise they were part of the sleeve that goes into carb. They were well and truly solid - managed to get 3 out with lots of swearing but 4th took several hours and no longer trumpet shaped! Looks like they corroded inside carb body. If the rest of car is like this - I'm doomed!

Question is - should they just slide in and out with hand pressure? Else can't see how to normally remove air box to get at carb fixings.

Also is there a recommended supplier, I've found one called Eurocarb who seems to have lots of stock. I'm looking to strip completely before ordering, the choke and throttle spindle seized so guess most other bits will be as well.

Cheers

Paul
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PostPost by: p.faurie » Wed Mar 02, 2022 10:27 pm

Hi Paul,the trumpets that hold the back of the air box are bolted on,held in place by 8x nuts/bolts
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PostPost by: mbell » Wed Mar 02, 2022 11:01 pm

Trumpets are meant to be easy push fit, with 8x nuts and fixing clips.

TBH I'd take a very long hard look at the carbs before ordering parts. The parts can add up quickly and if carb bodies are worn or have issues you might just be better buy new carbs.

I did a basic rebuilt my carbs and then had further issues. Decided it was better to spend a bit more and get new carbs rather than do keep throwing parts/money at the old ones.
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PostPost by: 512BB » Thu Mar 03, 2022 8:02 am

Completely agree with Mr Bell above. Carburettors are NOT infinitely rebuildable, they wear out, and parts for them are expensive these days.

Fortunately for me, some good folk on ebay think that old knackered Weber 18's and 31's will rebuild to as new, but I can tell you, they will not, and over the past couple of years, I have sold all such carbs that I had laying around. They may be rebuildable to LOOK great, but as for running great, that is entirely a different matter.

Unless you are certain that you have low mileage, in good condition mechanically carbs, that will rebuild to perfect condition, personally I replace with new these days.

I did that a few years ago with a pair of Webers that had been on the car from new. Car had covered well over 100k miles. Fitting a new pair of, unfortunately Spanish Webers, the engine now runs like the proverbial sowing machine, and that is without even a rolling road session, fantastic.

Personally writing, I prefer my cars to run correctly, rather than looking correct, but running like a dog, and unfortunately, you are not going to be able to tell if your carbs are going to be able to be rebuilt to RUN as new, until you have spent large wedge.

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PostPost by: 2cams70 » Thu Mar 03, 2022 8:56 am

512BB wrote:Completely agree with Mr Bell above. Carburettors are NOT infinitely rebuildable, they wear out, and parts for them are expensive these days.

Fortunately for me, some good folk on ebay think that old knackered Weber 18's and 31's will rebuild to as new, but I can tell you, they will not, and over the past couple of years, I have sold all such carbs that I had laying around. They may be rebuildable to LOOK great, but as for running great, that is entirely a different matter.


I have to disagree. The main issue is people not rebuilding them correctly or not cleaning internal passage ways thoroughly. 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. So far the argument seems to be "they are old, just not worth it, throw them away"!

On the other hand please keep throwing them away because I'll gladly take them!!!
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PostPost by: EPA » Thu Mar 03, 2022 9:12 am

The previous owner may have used some type of sealant on the trumpets in a bid to prevent fuel running out into the air box which can happen on these carbs.
This maybe why they were hard to remove.
I put new carbs on my car and they transformed the car.
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PostPost by: danbuoy1 » Thu Mar 03, 2022 11:37 am

Wow - thanks for all replies and greatly appreciated. As I mentioned when I pulled the first trumpet I assumed the cylinder was supposed to separate but now understand.

I suspect they're the original carbs and car having been stored outside for 30+ years corrosion has hit it. I can't verify mileage but over 80k judging by last MOT.

What is there to wear out other than butterflies (which were seized but now just turning, also choke)? I overhauled a couple of Stroms last year and replacing jet was main problem otherwise it seemed fine. But realise you guys have been here before so going by your experience and sounds like worth completely stripping and checking first and maybe look at replacements.

On another note, started thinking I'd be wise to look at engine before committing money, I know its "virtually" seized as will only move a gnats and assuming pistons but its the top end that I guess is more valuable and need to check?

Just haven't got loads of space and wary of creating boxes of bits rather than finishing things!

Cheers

Paul
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PostPost by: 2cams70 » Thu Mar 03, 2022 11:45 am

Unless you post pictures it really is difficult to make any meaningful assessment (even then it's hard!)
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PostPost by: Craven » Thu Mar 03, 2022 11:56 am

Wear on inside bronze bushes on the spindle location! What carbs are those?
Unless the pump jet bore in the body is bored and lined in refurbish your wasting your money.
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PostPost by: 661 » Thu Mar 03, 2022 11:57 am

I have brand new Spanish Webers on my race engine.
My engine builder seemed to suggest that the original Italian items were of a higher quality.
I have no idea why that should be the case, nor have I verified that myself. But I know he knows his stuff.
It may well cost as much to send them to a proper refurb specialist as to buy new, but that is what I would do.
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PostPost by: 2cams70 » Thu Mar 03, 2022 12:26 pm

Craven wrote:Wear on inside bronze bushes on the spindle location! What carbs are those?
Unless the pump jet bore in the body is bored and lined in refurbish your wasting your money.


The throttle shafts in a 40 DCOE are supported at their center by bronze bushes pressed into the body. These wear (usually to a not great extent) because they are subject to spring pressure acting on the shafts from the internal throttle return spring. See pictures

In my experience significant wear in the brass lining of the accelerator pump bore never happens.
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PostPost by: Craven » Thu Mar 03, 2022 12:44 pm

I’ve have never seen any bushing in this position, just 50yrs of working on DCOE’s though! Clever bit of machining to bore a larger hole in this position. Only very early carb’s have brass liners for the accelerator pump.
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PostPost by: 2cams70 » Thu Mar 03, 2022 1:09 pm

Craven wrote:I’ve have never seen any bushing in this position, just 50yrs of working on DCOE’s though! Clever bit of machining to bore a larger hole in this position. Only very early carb’s have brass liners for the accelerator pump.


These are 100% original 40 DCOE 31's off an Escort Twin Cam. They have never been apart before. original shafts, bearings, throttle screws and the original peening of them was all there as evidence that this was the case.

The pump bores were factory fitted with brass sleeves. They may be somewhat difficult to see because they are fitted only to the bottom 2/3rds of the bore and don't extend all the way to the top where the piston doesn't travel. They are definitely there though!
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PostPost by: smo17003 » Thu Mar 03, 2022 2:22 pm

YouTube has a number of videos explaining DCOE operation and rebuild processes. I found this series to be quite informative.

https://youtu.be/AHGSZtVhbx0
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PostPost by: Craven » Thu Mar 03, 2022 2:24 pm

I think the different observation are due to changes in manufacturing process over time, just looked a pair of old 2’s here they have inner bushes that seem made of a white soft metal. As part of changes these have petrol unions (top cover) in brass which I think was dropped on later carb’s.
When I get time I have a check on some other carb’s, I have some 2’s 18’s 28’s 31’s and 149’s.
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