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Guys

 

Just fitted these an the car. It started first push. Great so far. I took it up the lane (narrow in Devon) and had to pull over for horses(common in Devon), engine ticking over nicely but when applying throttle to pull away a loud bang and huge amount of vapour out of the carb side of the engine. So is engine running too weak or too far retarded or both? These cards reputably came off a 3a so jetting probably OK. I've read an article(http://www.tr3a.info/WeberDCOEinfo.htm) stating that ignition should be advanced and don't run vacuum advance on the distributor. Is this correct?

 

On parking the car back home there was fuel dripping out between the ramp pipes and the carbs(not a good situation when the exhaust stack is on the same side.

 

Thackery washers were over tightened on the manifold , so it may have been fuel frothing causing weak mixture. These have now been replaced but how tight should they be? The carb now do flex on the manifold as they should.

 

So I guess my question is :- do I advance the ignition, do I get rid of vacuum advance, or do I start playing with jets. I have a colour tune and vacuum gauge to check idle mixture and balance.

 

Or do I go back to the SU's?

 

 

 

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When I went the same route on my 3A I drove it to Aldon Automotive at Brierly Hill and had the engine set up by the professionals on their rolling road. Once set, never adjusted, excellent service whilst I waited. Aldon are Weber dealers and had all the jets/tubes to hand. Yes the vacuum advance was disconnected, but the distributor was adjusted (by them) to suit.

Good luck

Ian

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Indeed your first port of call is TeriAnn's website: http://www.tr3a.info/WeberDCOEinfo.htm, added with ntc's tip: a pressure regulator! There's a fair chance that the pump wasn't able to cope with the 'demand' from the carbs when you pulled away during your test drive. It's all about the complete chain of components that make Webers work.

 

Menno

 

(BTW, was there ever an interview or special about TeriAnn in TRAction?)

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If you are getting fuel dumped check the float heights. These carbs are very flexible and it is possible to get them to run well but with the fuel level too high and using the jetting/tubing to lean them out. In this configuration they will tend to bleed excess fuel out of the chokes,. btdt.

 

Stan

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Thanks Guys

 

Articles that I have read indicate that the original fuel pump is OK. I don't have a pressure regulator fitted(yet).I'm thinking it was fuel frothing caused by the Thachery washes being done up too tight, causing the engine to run weak. These have now been adjusted and the cards now flex on the manifold as they should. I'll give it another run and report back. If that doesn't work then float levels next then ..........

 

Aldon Automotive at Brierly Hill - about 200 miles away! - a bit risky unless it's trailered up there I think.

 

 

Barry

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Frothing tends become an issue over 5200rpm- one of the reasons these engines were red-lined at 5000, as of course all SUs were rigidly mounted. Flex-mounted SUs (eg TR7) will allow an engine to rev forever.

Just a few points for you to consider:

Worn float chamber needle valves- very easily replaced, like an SU.

Float height - reset to 11mm after valve replacement; really worn valves cause the float to sit higher.

Make sure neither float is punctured.

Screw all four idle adjusters fully home clockwise, then unwind three turns to give a good base idle setting. Stumbling & spitting: unwind until it ceases, wind in again 1/4-1/2 turn.

Balance them at idle with a piece of fuel hose (empty) poked in one ear; listen carefully & you won't need a posh flow meter.

If you have removed the lids to change valves & clean inlet filters, get brave & unscrew one each of the progression & main jet assemblies.

The side of the prog nozzle will be stamped xxFx - 45 or 50 F8 is the norm here. Too small= lean, too big= rich.

There are three parameters to consider in the main jet units:

First, at the bottom, main jet: expect to see 125-140 in increments of 5 stamped here.

Second, on the side of the large (emulsion) tube: F9, F11, or F16.

Third, pull off the slotted cap at the top (pliers help) & expose the air corrector jet. Expect to see 150-185 in increments of 5 stamped here.

If possible, peer down the intake end & try to make out the main venturi size cast into it- 30, 32, or 34 are commonest here.

Please post here or PM?

Webers are nowhere near as scary to work on as some like to pretend; nor do they "go out of tune".

Finally, if all goes well, consider replacing the dodgy double "O" ring carb-manifold seals with one-piece Misab rings (beware of unbranded copies), ditch the Thackeray washers & replace with plastic donut & cup washer kits for total reliability.

Sorry to bumble on so, but Webers really can be a pleasure to work on & are ultimately less problematic than SUs as they wear so little. Good luck.

SPMPW

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Barry

 

Persevere with the Webers.

 

My set up is slightly different: electric pump, pressure regulator (as per Neil), and 45s (they came with the car and are probably too much), and it ran terribly!

 

I did not have the time to learn and have a go as SPMPW proposes (still some interesting information) so I invested the time finding an old school Weber tuner with a rolling road. Within 5 minutes he had swapped the idle jets and replaced the plugs with four NGK B6HS plugs (used on motorbikes I think) with a 34 thou gap I think. Car transformed and they do not "go out of tune".

 

Petrol consumption however is a bit of a challenge but hey, that's what you pay for performance.

 

Miles

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In the autumn of 1962, the Works fitted twin Webers to the TR4 Rally cars. These used the mechanical pump (no electric pump was Homologated, so not allowed) and ran to 6000 rpm, according to Graham Robson - and they were climbing the Alps to a height of 9000 feet, rather more than one can find in the UK!

Ian Cornish

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Finally, if all goes well, consider replacing the dodgy double "O" ring carb-manifold seals with one-piece Misab rings (beware of unbranded copies), ditch the Thackeray washers & replace with plastic donut & cup washer kits for total reliability.

 

SPMPW

So where can we locate purchase these from ???

Roy

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They probably used an uprated pump that was matched to the cam, looked like a homologated part !! (Rallying builds are using what looks right to a scrutineer) and of course perfectly legal, I mean as soon as there was lift on the lever, the fuel moved, that is not always the case, if you have to use a engine driven original pump, fit it to the block during engine build and check its delivery with real petrol, or you get that lovely noise from the pump sucking air as soon as the lever starts to rise, but check this from the sump end, I have done the same thing by brazing a nice patch of bronze on the cam lever that takes up the slack, lost motion, in the mechanism, but a red top electric pump and regulator are better.

 

John

Edited by TR24178
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Ianc,

 

Wouldn't the works have been using 42 Webbers anyway ?

 

Mick Richards

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Ianc,

 

Wouldn't the works have been using 42 Webbers anyway ?

 

Mick Richards

They sure would work the best on a rally car, where torque is king, if I may draw a comparison with my Pinto engine MKII escort on 48's, hard work to keep it on the cam much improved on 45's

John Worthing

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Triumph Homologated both 42 and 45DCOE Weber carburettors (and Strombergs - a number of items were Homologated "just in case").

I don't know which model was used, but whichever it was. the carburettors are still fitted to 6VC and 3VC. I will ask Neil and Tony.

Ian Cornish

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Neil has confirmed that 6VC is on twin 45s. And Tony says that 3VC is on twin 45s. This is as I had expected.

Tony's continues:


"BST (Beastie) is on twin 45s, however the big power car (it produces around 200 BHP) really needs 48s. As far as I'm aware, 42s can't supply enough fuel to go beyond about 130bhp. Neil reckoned that 3VC was over 150bhp on his rolling road some years ago. Kastner reckons that two SU HS6 were good enough for up to 155bhp and Strombergs a little more. My 4A, LDU753F, had about 145 on HS6s, so I'd go along with that. I sold the twin 42s that I had on the basis that they were rare and valuable chocolate tea pots!"


So there you have it!


Ian Cornish

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Guys

 

I've just found out that Thackerary washers should be tightened with lock nuts until the gap between the coils is 20-40 thou.

 

"Ditch the Thackerary ....... and replace with plastic cup and washer kits"?

 

Re the article :-http://www.tr3a.info/WeberDCOEinfo.htm and setting up the idle - "just about everyone goes wrong ...." it seems to me that the manufacturer did not intend these to be adjusted(white caps) expect at the factory (matching paired/triples?)

 

I will persevere with the webers but am just a bit nervous about the dripping fuel.

 

I'll remove the vacuum advance when a BSPT blank plug arrives.

 

There doesn't seem to be a Weber specialist in SW England

 

Barry

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Guys

 

I've just found out that Thackerary washers should be tightened with lock nuts until the gap between the coils is 20-40 thou.

 

"Ditch the Thackerary ....... and replace with plastic cup and washer kits"?

 

Re the article :-http://www.tr3a.info/WeberDCOEinfo.htm and setting up the idle - "just about everyone goes wrong ...." it seems to me that the manufacturer did not intend these to be adjusted(white caps) expect at the factory (matching paired/triples?)

 

I will persevere with the webers but am just a bit nervous about the dripping fuel.

 

I'll remove the vacuum advance when a BSPT blank plug arrives.

 

There doesn't seem to be a Weber specialist in SW England

 

Barry

See my post no 8 above they arent very far from you.

Stuart.

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Guys

 

I contacted Mike at Ratt Racing - a very helpful man. He told me that some dripping is common with 40's. Mine is only a small amount and I'm probably OK although he told me that a lot of Lotus Elans have been lost due to fire ( probably caused by fuel leaking over starter motors).

 

Anyway I'll try what I can and if I can't get it right Ratt Racing in Torquay(10 miles away max) will have it.

 

Thanks for all the help and suggestions

 

Barry

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Barry,

Having had a fair bit of work carried on my TRs,both webered cars,over the years i can recommend Mike Tarr as someone who really understands the workings of webers and also charges sensible prices for that work. I have no financial interest just a satisfied customer,

cheers,

Laurence

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