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Skinners Union Carbs seem to be more preferable than the Stromberg carbs fitted to my US TR6.

 

Why is this? can the more enlightened please explain exactly why?

 

I would hope the "Advvantages" would surely justify the cost, but once again do they, and is it worth it for

 

ordinary driving.

 

And! some blind racing driver knocked the wall down last night round our Donkeys compound, no one saw a thing

 

but the damage to the car must have been extensive, headlamp lights and plastic everywhere!

 

Barstewards, the last time an arctic tried to get up the road the damage cost £4K.

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Edited by pfenlon
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Skinners Union Carbs seem to be more preferable than the Stromberg carbs fitted to my US TR6.

 

Why is this? can the more enlightened please explain exactly why?

 

I would hope the "Advvantages" would surely justify the cost, but once again do they, and is it worth it for

 

ordinary driving.

 

And! some blind racing driver knocked the wall down last night round our Donkeys compound, no one saw a thing

 

but the damage to the car must have been extensive, headlamp lights and plastic everywhere!

 

Barstewards, the last time an arctic tried to get up the road the damage cost £4K.

 

 

There is (was) more choice of parts, especially needles and jets and some people do not like the rubber diaphragms etc. But that situation has changed as Burlen now produce replacement parts. There are also people who think that SU's produce more power? I have my doubts about this but have no evidence either way?

 

Bruce

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Peter,

If you have the later Strombergs , 175-2, they have USA-emissions kit that the simpler HS6 SUs lack.

That means more to go wrong and more to fathom....

I doubt there's much if any performance difference.

Peter

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And needles that are machined with 1/1000 millimeter precision - that's 1/25th thou .

So no tuning the needle with carborundum paper.

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Sorry guys, got to be EFI.

Marki, you are quite right, but having had PI, the power is there, but the problems are manifold and niggling, new injectors that don't work 100%, tapping lines, delivery pumps, pressure regulators, all IFFY to say the least.

 

I want it to just work properly 100% of the time. PI won't do that.

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Hi Pete.

Yep that's why I converted, endless niggles.

So worth the effort. Mark.

The Pi cars would do 80k plus as most of them did with service done correct, the downfall is down to those that mess with it not knowing how to.

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Did not get it right then? left for sombody else to sort out after you sold again. ;)

Well good evening, My first PI car I sold to Colin at CTM, the price was reasonable, the PI system when I sold it worked, not even you can guarantee how long it would work for.

 

The second TR5 I sold to Mr Mountford from the Stoke group, he and ourselves did go round the WW1 battlefields in Belgium, and it got him there and back without mishap.

 

as always I do a decent job after advice from those on the forum who are prepared to help, and of course explain themselves FULLY.

 

Since selling I have had no complaints from the new owners.

 

Please refrain from showing your yellow balls with slitty eyes after each post, its most disconcerting, especially for the ladies.

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Hi Neil.

I'd like to see a PI car that's done 80k without problems with the fuel system.

Mark.

Mine did 150k with no servicing. Only had to replace the Lucas pump at 150k when it started weeping. Daily driving explains why.

Carried a spare injector - never needed it. Only problems were with the butterflies going out of sync.

But I can recommend one SU and a blower as an alternative.

Peter

Edited by Peter Cobbold
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Neil, I understand it is a design of the car and as so is part of the original concept. Reliability is not its finest hour though, more and more people are wanting to use these cars in a reliable fashion and as such I think EFI gives the best results without turning to carbs.

Mark.

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For what its worth, I run a pair of 45mm Mukinis and love them, just seems to breath so much better

I've never had to touch them since I fitted them.around 3 years ago although I should try and get a bit more to the gallon.

Initially I had to play around with fuel pressure, pedal travel, chokes and modify the air filters but was up and running in a day.

For me, Mukinis are the way forward.

 

Cheers H.

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Edited by hman
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Hi Neil,

 

"The Pi cars would do 80k plus as most of them did with service done correct"

 

You weren't driving PI cars back in the day, as by the time you turned 17 Triumph had stopped making them . . . . . In contrast, by then I'd had 8 years driving including TR5 and 6 and 2.5PI saloons, and a 2 litre PI GT6.

 

The idea that they were trouble free or the PI system good for 80,000 trouble free miles is simply wishful thinking. Absolute Cobblers. Total Bollocks if you prefer.

 

Of course the odd PI car just ran like clockwork, but that was the exception rather than the rule, and nothing remotely like an average. If you had a local dealer with a mechanic who actually understood PI then you had a fighting chance, but such laddies were not that common and tended to move on to greater things.

 

Agreed the key aspect was finding the right man to set up the system correctly in the first place, and to then ensure that the owner kept his fingers well away from the PI system . . . . easier said than done, on both counts. And then regular servicing by the book.

 

But that didn't alter the fact that Lucas and Triumph alike suffered from deteriorating quality control through the 70s - and it showed in the PI system. Nor must we forget that the harder a PI car was driven, the more likely it was to throw regular hissy fits. As numerous police forces demonstrated.

 

I liked the PI system as much as anybody, and still do - but it was a race system inadequately detuned for road use, and we do it no favours by reinventing the past as some fantasy golden age.

 

Cheers

 

Alec

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Hi Neil,

 

"The Pi cars would do 80k plus as most of them did with service done correct"

 

You weren't driving PI cars back in the day, as by the time you turned 17 Triumph had stopped making them . . . . . In contrast, by then I'd had 8 years driving including TR5 and 6 and 2.5PI saloons, and a 2 litre PI GT6.

 

The idea that they were trouble free or the PI system good for 80,000 trouble free miles is simply wishful thinking. Absolute Cobblers. Total Bollocks if you prefer.

 

Of course the odd PI car just ran like clockwork, but that was the exception rather than the rule, and nothing remotely like an average. If you had a local dealer with a mechanic who actually understood PI then you had a fighting chance, but such laddies were not that common and tended to move on to greater things.

 

Agreed the key aspect was finding the right man to set up the system correctly in the first place, and to then ensure that the owner kept his fingers well away from the PI system . . . . easier said than done, on both counts. And then regular servicing by the book.

 

But that didn't alter the fact that Lucas and Triumph alike suffered from deteriorating quality control through the 70s - and it showed in the PI system. Nor must we forget that the harder a PI car was driven, the more likely it was to throw regular hissy fits. As numerous police forces demonstrated.

 

I liked the PI system as much as anybody, and still do - but it was a race system inadequately detuned for road use, and we do it no favours by reinventing the past as some fantasy golden age.

 

Cheers

 

Alec

Alec, Then I must have been very lucky to get 150k trouble-free miles from my '74 CR-series, spread over ten years daily driving.

I carried spare pump and injector- never needed. The diaphragms never perisehd. The occasional over-run backfiring I lived with. And 27mpg on a run was OK. I did have a stuck prv a year after ceasing dd and driving intermittently.

My view is the PI doesn't like inactivity , nor perhaps ethanol fuel.

I did curse the butterfly linkage, but that presumably was down to Triumph not Lucas.

Peter

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Skinners Union Carbs seem to be more preferable than the Stromberg carbs fitted to my US TR6.

 

Why is this? can the more enlightened please explain exactly why?

 

I would hope the "Advvantages" would surely justify the cost, but once again do they, and is it worth it for

 

ordinary driving.

 

And! some blind racing driver knocked the wall down last night round our Donkeys compound, no one saw a thing

 

but the damage to the car must have been extensive, headlamp lights and plastic everywhere!

 

Barstewards, the last time an arctic tried to get up the road the damage cost £4K.

 

The SU's are simpler. The Strombergs have diaphragms that rupture and some models (as used on the TR6) have temperature compensators on the side that go wonky. Then there is the Stromberg contribution to the Rube Goldberg designed idle emissions doohickey hanging off the rear carb. Better still would be 9.5:1 head, the PI cam and three SU's.

 

Stan

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And needles that are machined with 1/1000 millimeter precision - that's 1/25th thou .

So no tuning the needle with carborundum paper.

 

So back to the carb comparison:

 

As said one bigger problem of the Strembergs is that there are not many

neddles availiable.

Why do we need needles?

When engine has been modified or the engine had ex works to fullfill crazy laws

and is set to bad performancethey are essential. Example is the ignition retard capsule

or the much too much leaning of the US models in in the midrange/part throttle.

 

Peter is correct, needles are precision instruments.

But if we think that to the end, what does that mean, if needle is wrong?

 

Let us say the needle is too lean in a defined area and gives AFR 15

where 12.5 would be nice.

There we have precision but its wrong and far away from proper size.

 

If you grind the needle you might end up with 12.8 AFR at the left

and because precision is difficult maybe 12.6 at the right carb.

I would prefer that close to perfect match instead of precisely made

needles but away from the required size.

 

If Stromberg & modified engine is envisaged this is a basic decision that must be made:

Am I willing and able to modify the existing needle to fit better?

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+1 for Alecs view.

But I will attempt to re-commision the PI system on my CP car, and will do everything to make it work. Can't wait until I fire her up and all works as intended (hopefully).

Nevertheless, EFI is still in the back of my head.

Without the excellent help on this forum I would never been able to tackle this, we do not always have to agree, but I respect other opinions, as the past has learnt me I was not always right.

Best regards,

Waldi

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After seven plus years of driving on EFI I forget the troubles of Lucas PI .

Interestingly after changing my wheels to Silverstone ARE copies and fitting Vredestien Classic Sprints 185 x 70 x 15 tyres and driving around on a very wet track and pouring rain in SPA

my TR5 stuck to the surface like glue which gave me huge confidence to push harder. Lovely tyres.

Great trip and we all got back.

Regards Harry TR5 Nutter

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After years of driving a GT6 with emission Strombergs, a CP-series TR6 with Lucas PI and a few cars with SUs in the past, here's my two penny worth...

 

The Strombergs are very good carbs. After overhauling with new diaphragms, needle valves and seals, followed by careful setting up, they perform well and have held their tune for years. I never had a problem (yet) with the emissions temperature compensation and never had a problem with the diaphragms. The only downside if you're running a non-standard setup is the limited range of needles. In my experience, the Strombergs have held their tune better than SU-carbed cars I've had in the past but that may simply be because I took more trouble setting up the Stroms. Both SUs and Stroms are very good carbs, at least for road use.

 

I also rate Lucas PI highly, as long as it is well looked after. My TR6 has been reliable, the only issues have been due to specs of dirt lodging in the injector tips and causing the injectors to dribble and occasionally the need to rebalance the throttle butterflies. As with the carbs, careful setting up is the key to long-lasting good performance and I've enjoyed taking the time to understand the PI system. I'm sure EFi can improve on the fuelling accuracy across the range compared to PI but I'm not tempted. I love the period quaintness of the PI setup. The PI ain't broke, so I'm not going to fix it.

 

 

Nigel

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