Carburettor for TR4A (Newbie to TR4a)

[01alam]

Hello All,

 

Its been a while since I have been on this site, I have been busy sourcing parts to rebuild my TR4a in Hong Kong. These questions may seem a little strange but I am new to Triumphs and carburettor engines. Which carburettor is the best for a TR4a? My mechanic has told me that my car has the fixed needle type (so I guess it is the CD ones?) and the car would benefit from upgrading the carbs. I have been recommended SU, but what are Weber like? Which is smoother and more reliable, and also which is more powerful? Where would be the best place to look at buying these? I have been looking at Rimmer Bros. website and they seem to only sell SU, and is classified as Front and Rear Assembly? Sorry for being so ignorant, but I have been reading on websites and the books I have bought, but still don't have a clue. I would really appreciate your help.

 

Many Thanks,

Angus

[stuart]

Hello All,

 

Its been a while since I have been on this site, I have been busy sourcing parts to rebuild my TR4a in Hong Kong. These questions may seem a little strange but I am new to Triumphs and carburettor engines. Which carburettor is the best for a TR4a? My mechanic has told me that my car has the fixed needle type (so I guess it is the CD ones?) and the car would benefit from upgrading the carbs. I have been recommended SU, but what are Weber like? Which is smoother and more reliable, and also which is more powerful? Where would be the best place to look at buying these? I have been looking at Rimmer Bros. website and they seem to only sell SU, and is classified as Front and Rear Assembly? Sorry for being so ignorant, but I have been reading on websites and the books I have bought, but still don't have a clue. I would really appreciate your help.

 

Many Thanks,

Angus

Angus your best bet would be to try and source some 1 3/4" SUs as they are the best all round carbs for the 4a and will fit the manifold currently on your car. Webers are nice but without upgrading the rest of the engine wont produce that much more power than SUs, (do sound nice though!) and they require different inlet manifolds.

Burlen Fuel supplies 01722 412500 sell brand new sets as does Andrew Turner (dont have phone number but a search on here may turn it up) Second hand SUs do turn up on ebay but bear in mind they will probably need a rebuild so cost of that needs to be factored in.

Stuart.

[01alam]

Angus your best bet would be to try and source some 1 3/4" SUs as they are the best all round carbs for the 4a and will fit the manifold currently on your car. Webers are nice but without upgrading the rest of the engine wont produce that much more power than SUs, (do sound nice though!) and they require different inlet manifolds.

Burlen Fuel supplies 01722 412500 sell brand new sets as does Andrew Turner (dont have phone number but a search on here may turn it up) Second hand SUs do turn up on ebay but bear in mind they will probably need a rebuild so cost of that needs to be factored in.

Stuart.

 

Thanks Stuart,

 

I will phone them on Monday to see if those are in stock. So what else do I need to upgrade in the engine to get the full advantage of the Weber?

 

Regards,

Angus

[TR 2100]

Which carburettor is the best for a TR4a? My mechanic has told me that my car has the fixed needle

type (so I guess it is the CD ones?) and the car would benefit from upgrading the carbs. I have been

recommended SU, but what are Weber like? Which is smoother and more reliable, and also which is

more powerful? Where would be the best place to look at buying these? I have been looking at Rimmer

Bros. website and they seem to only sell SU, and is classified as Front and Rear Assembly?

Hi Angus,

 

There's not a lot to choose between SUs and Strombergs - it was only factory

policy that prompted the change, so better to stick with the ones you have and

recondition.

 

Upgrading to Webers (40s in your case) would probably be more hassle than it's

worth. Yes, some performance increase but to get any real benefit from Webers,

you would want to fit a 4-branch, do some head work, slightly hotter cam etc.

Webers may be able to deliver more mixture but you have to get rid of the exhaust

gases before you can benefit much, and that is the primary limiting feature on the

standard setup

 

Think also electric fan for driving in Hong Kong and maybe alternator as you don't

get so many long runs in Hong Kong to charge the battery.

 

Best place for s/h bits is eBay - no duties when importing to Hong Kong and there's

nowhere/nobody locally these days that has any of these bits.

 

AlanR

[david ferry]

Angus,

 

Andrew Turner's website

 

This contains all of his contact details and also information on what he does.

 

His website does not state the fact that he often has reconditioned carburettors and manifolds for sale.

 

Certainly worth contacting him.

 

Good luck

 

Regards

 

David

[01alam]

Hi Angus,

 

There's not a lot to choose between SUs and Strombergs - it was only factory

policy that prompted the change, so better to stick with the ones you have and

recondition.

 

Upgrading to Webers (40s in your case) would probably be more hassle than it's

worth. Yes, some performance increase but to get any real benefit from Webers,

you would want to fit a 4-branch, do some head work, slightly hotter cam etc.

Webers may be able to deliver more mixture but you have to get rid of the exhaust

gases before you can benefit much, and that is the primary limiting feature on the

standard setup

 

Think also electric fan for driving in Hong Kong and maybe alternator as you don't

get so many long runs in Hong Kong to charge the battery.

 

Best place for s/h bits is eBay - no duties when importing to Hong Kong and there's

nowhere/nobody locally these days that has any of these bits.

 

AlanR

 

Hi AlanR,

 

Thanks for the tip, I think the car has got an Electric Fan? By the way, did you get my PM, and I hope your TR4 is going well.

 

Angus

[01alam]

Angus,

 

Andrew Turner's website

 

This contains all of his contact details and also information on what he does.

 

His website does not state the fact that he often has reconditioned carburettors and manifolds for sale.

 

Certainly worth contacting him.

 

Good luck

 

Regards

 

David

 

Hello David,

 

Thanks for the help. Will definitely contact him, and see what he has in stock.

 

Many Thanks,

Angus

[Alec Pringle]

Hi Angus,

 

The Strombergs can work just as well on a standard 4A as SUs.

 

If you have a competent local man in HK (if not, Alan Robinson may know one), the simple answer is to purchase a reconditioning kit and let him get on with it.

 

It's all too easy to spend unnecessary money on replacement SUs, for no real benefit over reconditioning your existing Strombergs. Strombergs are unnecessarily maligned - they didn't work well on everything for sure, but they did on 4As

 

Cheers,

 

Alec

[01alam]

Hi Angus,

 

The Strombergs can work just as well on a standard 4A as SUs.

 

If you have a competent local man in HK (if not, Alan Robinson may know one), the simple answer is to purchase a reconditioning kit and let him get on with it.

 

It's all too easy to spend unnecessary money on replacement SUs, for no real benefit over reconditioning your existing Strombergs. Strombergs are unnecessarily maligned - they didn't work well on everything for sure, but they did on 4As

 

Cheers,

 

Alec

 

Hi Alec,

 

Many Thanks for the help. I might in that case see if I can find some Strombergs, but am I right in saying that Strombergs are non-adjustable?

 

Angus

[Rhodri]

Angus, the CD carbs you have are Strombergs, they have tops like a very squashed bottle? They have the usual adjustment for mixture, but anything else you need different profile needles. They are very similar to the SUs. As others have suggested, if you are keeping things more or less standard then stick with the carbs that you have.

[01alam]

Angus, the CD carbs you have are Strombergs, they have tops like a very squashed bottle? They have the usual adjustment for mixture, but anything else you need different profile needles. They are very similar to the SUs. As others have suggested, if you are keeping things more or less standard then stick with the carbs that you have.

 

Hi,

 

Thanks for the help. So the CD carbs are actually adjustable for fuel air mixture?

 

Angus

[knapman]

Hi Angus

The debate on which is the best carbs,SU or Stromberg has been

going on for years. What ever works best for you is what counts.

I rebuilt my Strombergs but couldn't get a steady tickover what-

ever anybody tried. Eventually, by recommendation of people

who know, i got SU's & all was well.

As Stuart says, who rebuilds TR's, SU's are the preferred carb

by TR specialists.

Whenever i had my CD's looked at they all said get rid of them.

I'm sure there's people out there that can make them

brilliant but SU's are known the world over & spares are

readily available.

If you stick with the CD's make sure you get new rubber

diaphragm's when you rebuild them.

Thats the main differance between the two types otherwise

they are almost the same.

 

Hope i havn't muddied the waters too much.

 

Best of luck

Bob K

[ianc]

Thus far, no one has mentioned that when the diaphragm goes on a Stromberg, the engine will produce no power (well, perhaps a little power, as there are two carbs on a TR4A). It is possible for the piston to stick on a TR, but it's very, very rare if you have air filters fitted.

Because they were so widely used, the variety of needles available for SUs (should you wish to start playing) must be far greater.

The utter simplicity of the SU is its great virtue.

Ian Cornish

[01alam]

Thanks Ian and Bob,

 

I have spoken to my mechanic again, he suggest that I go for the SU's since I am planning to use the car quite often, possibly 3 times a week on 30 miles round trips, and he suggests that the SU will get the temperature up much quicker and also eliminate the use of the manual choke, since it is quite warm in Hong Kong. I will definitely keep you updated, the problem with the CDs at the moment is the booming and buzzing it has when started up.

 

Angus

[knapman]

[quote name='01alam' date='May 13 2008, 12:48 PM' post='9

he suggests that the SU will get the temperature up much quicker and also eliminate the use of the manual choke,

 

Angus

 

 

Angus

I dont think any type of carbs will have this

affect unless i'm missing something.

Someone more knowledgable than me may be able to advise.

 

Best of luck

Bob K

[67_gt6]

If the temperature necessitates it both types of carb will require use of the choke, however the method is different - Strombergs use a starter bar which raises the piston (and thus the needle in the jet) but "chokes" the airflow, SUs drop the jet.

 

Needle choice is undoubtedly greater for SUs, although www.Burlen.co.uk have a fair range of Stromberg needles.

 

As far as I can remember the tolerances between the piston and dashpot are not as tight on Strombergs as the diaphragm provides the seal so arguably they may be slightly less likely to stick.

 

In thousands of miles on Strombergs I never suffered a torn diaphragm however I did carry a couple of spares.

 

The big advantage with SUs is that it is much easier to set the float level - with Strombergs you have to remove the carbs and invert them to measure it.

 

Andy

[01alam]

Thanks Andy and Bob,

 

I have contacted Burlen yesterday and now they are building a set of SU for me. Many Thanks for the help.

 

Angus

[knapman]

Am sure its the best route considering your location.

You might have to source some linkages, not sure

what they were on a 4A with SU's

 

Best of luck

Bob K

[stuart]

4a equipped with SUs would have a centre linkage originally but it may be possible to use the Stromberg linkage working on the front end with a little modification. I suspect if Angus is having a Burlen complete set they may come with the centre bracket anyway.

Stuart.

[TR 2100]

I have spoken to my mechanic again, he suggest that I go for the SU's since I am planning to use the car quite often,

possibly 3 times a week on 30 miles round trips, and he suggests that the SU will get the temperature up much quicker

and also eliminate the use of the manual choke, since it is quite warm in Hong Kong.

 

Is it only me that is starting to get a bit worried about your 'mechanic'?

 

AlanR

[Alec Pringle]

No Alan,

 

You're not the only one getting worried !

 

Mechanics have always been prone to spout codswallop when confronted with something they don't understand, or just plain don't like, but this particular load of old cobblers takes some beating . . .

 

It's certainly a new one on me.

 

If that's his considered view on the respective merits of Strombergs and SUs, I wouldn't even let him open the box that the new SUs come in.

 

I don't know how many cars I've run on Strombergs over the years, double figures, and I've never ever had a problem with any of them. Just lucky, I guess.

 

Cheers,

 

Alec

[01alam]

Thanks Bob and Stuart for the info.

 

Alan and ALec, I think I will need to speak with the mechanic again to see the actual ideas behind having the SU, will let you know, the thing is the strombergs are rather tired and not sure if that's the reason behind the booming and banging from the engine.

 

Angus

[ianc]

I've never run a car with Strombergs, but have seen two instances of torn diaphragms (old age) on single-carburettor BL cars - cannot now remember which models. In both cases, the engine would scarcely run and the car was not driveable.

Ian Cornish

[01alam]

I've never run a car with Strombergs, but have seen two instances of torn diaphragms (old age) on single-carburettor BL cars - cannot now remember which models. In both cases, the engine would scarcely run and the car was not driveable.

Ian Cornish

 

Thanks Ian,

 

Angus