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pi conversion to carbs


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That's a big step , you could go backwards in performance unless you go to an expensive Weber set up. 

What fuel do you use? Do you use the car often? I add Stabil for winter storage.

Maybe EFI is worth a look if you want to change from the original Lucas  PI. 

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A well set up and regularly used PI system is very reliable.

since i put refurbed injectors in mine at the end of 2012 i have had zero problems with the PI system in more than 7 years and 20k miles

steve

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2 hours ago, Steves_TR6 said:

A well set up and regularly used PI system is very reliable.

since i put refurbed injectors in mine at the end of 2012 i have had zero problems with the PI system in more than 7 years and 20k miles

steve

Same, my PI has had no PI issues since I bought it nearly 4 years ago and about 15,000kms. Use it regularly and put some top end lubricant in the fuel occasionally.

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Same here...I had my whole PI system overhauled a couple of years ago and have had no problems whatsoever (touch wood)... I do know though that modern fuels tend to "go off" a lot quicker than the old stuff...I always leave at least half a tank in it when not using it and start it up once a month

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When I acquired my latest Tr6 21 years ago it came with triple Weber’s. I was familiar with Weber’s having had them for many years on a Lotus Cortina. 
That said in your situation I would strongly recommend sticking with the fuel injection and sorting out what issues you have. 

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I'm another fan of Lucas PI.

When in good condition and properly set up it's reliable and I've never had a problem that could be attributed to modern petrol (running on Tesco Momentum or Shell V-Power).

SU carbs will be reliable but reduce performance and value, as has been said. I've no direct experience of Webers but a respected Triumph trader told me recently that they need regular re-tuning, so if true the Weber option may need at least as much fettling as Lucas PI.

Nigel

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2 hours ago, Nigel Triumph said:

 I've no direct experience of Webers but a respected Triumph trader told me recently that they need regular re-tuning, so if true the Weber option may need at least as much fettling as Lucas PI.

Nigel

No thats not true, once tuned they do not need any fiddling with at all.

Stuart.

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1 hour ago, stuart said:

No thats not true, once tuned they do not need any fiddling with at all.

Stuart.

Hi Stuart,

Thank you for straightening that out. Perhaps I had better not name the trader who clearly dislikes Webers!

Nigel

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1 hour ago, stuart said:

No thats not true, once tuned they do not need any fiddling with at all.

Stuart.

That's been my experience over 24 years and 135,000 miles. Nothing else on the entire vehicle is as reliable.

The sole drawback to Weber DCOEs is the challenge of calibrating them for the application. This is evident from the steady stream of used ones for sale. 

While quite a few LUCAS P.I. systems have been converted to DCOEs, I haven't seen the converse reported, though surely there must be some cases where it has been done at least for the sake of originality :huh:.

 

Tom

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44 minutes ago, Nigel Triumph said:

Hi Stuart,

Thank you for straightening that out. Perhaps I had better not name the trader who clearly dislikes Webers!

Nigel

Why Not? they do not know what they are talking about so I wonder what else they don't know.

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2 hours ago, stuart said:

No thats not true, once tuned they do not need any fiddling with at all.

When I acquired my car the first thing I did was book it into Cambridge Motorsport on the Monday after an international weekend. I can’t remember the name of the guy who did the work, put he certainly knew what he was doing. That was over 20 years ago and since then I check them everything few years with a couple of colour tunes and a flow meter. That’s it. 

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3 hours ago, Tom Fremont said:

That's been my experience over 24 years and 135,000 miles....

 

Tom

“. That was over 20 years ago ”

Jury still out then Tom And Cameron !

steve

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Just recently had a local drive the triple webers and PI back to back on a long haul drive.  He reckons he'd take the PI (CR) over Webers any day.

Both sound to me like setup is fiddly and best done by someone who knows what they're doing and after that are good if left alone.

Personally I'd keep the PI, if only for it's uniqueness.

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I understand that the reputaion for unreliablity of Pi came from Triumph's notorious stingyness.

This was the first application of Fuel Injection in a production car in Europe, if not the world, but Triumph made no investment in training dealers or their staff in the new technology.   As a result, when they came into the workshop, the mechanics thought they could twiddle with it like you can with a carburettor, but rapidly lost their way in the three dimensional, adjustment of the Pi metering unit and more importantly, could not find it back again.     After all, on an SU, you can always screw the jet right up, back off three turns and start again. 

When the cars didn't run right, the new Pi was blamed.  As all above can attest, falsely.

JOhn

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16 hours ago, john.r.davies said:

I understand that the reputaion for unreliablity of Pi came from Triumph's notorious stingyness.

This was the first application of Fuel Injection in a production car in Europe, if not the world, but Triumph made no investment in training dealers or their staff in the new technology.   As a result, when they came into the workshop, the mechanics thought they could twiddle with it like you can with a carburettor, but rapidly lost their way in the three dimensional, adjustment of the Pi metering unit and more importantly, could not find it back again.     After all, on an SU, you can always screw the jet right up, back off three turns and start again. 

When the cars didn't run right, the new Pi was blamed.  As all above can attest, falsely.

JOhn

And that Lucas pump that fails in warm weather, we get that weather in mid winter.

It seems to me that a Bosch pump conversion solves nearly all PI issues, the rest are solved by experienced physical PI specialists. It was used on the Maserati and on a Porsche I believe..

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And on racing Ford Capris and Minis.   Recently,  I posted here scans of an article from 1956, about an early version of Lucas Pi, as fitted to Jaguar racers.   It was a lot more complex!  See: https://www.tr-register.co.uk/forums/index.php?/topic/71386-pre-triumph-lucas-pi/&tab=comments#comment-650769

Having shot themselves in the maintenance department, Bosch came up with the K-tronic system which was so much simpler, primitive even ('K'ontinuous, single point injection) and so much cheaper, that the Lucas system died.

 

 

Edited by john.r.davies
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