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Hi all

i am progressing with my 72 cp and I find myself wondering about originality over reliability and performance regarding the fuel injection system,I have seen carburettor set ups that look positively mouth watering.Or should the original Lucas set up be adhered to or is the Bosch set up more reliable,the car does not run well and the running issues will be my next task so now may be the best time to consider different options and as ever cost will become a consideration.Above all though reliability will be the watch word,any thoughts would be welcome from this ever knowledgeable bank of wisdom 

regards nige

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Hi Nigel,

whatever TRiumph did in the 60's & 70's was based on cost of production and what was available.

If they were designing the TR6 today it would have EFI and your problems would be gone. But that choice was not available at the time.

So, what ever you do to your car it will still be your car and more importantly a TR6 (as TRiumph would have it)

I have a TR4A. It was designed with a dynamo. when I got it I put an alternator on it - as TRiumph did  to the TR5 in the next generation of model.

It now has all sorts of modernity added to it - because that is what 'I' want and what TRiumph would have done.

 

So, don;t hang back trying to please those that only want originality. Do what YOU want.  Let's face it, it can always be put back to original spec if need be.

 

Roger

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The TR5/6 PI system can be 100% reliable once set up and if used regularly

i’ve had 2 6’s and both had the original PI system with a Bosch pump and were totally reliable.

The current car i’ve owned for over 8 years and 24k miles, after initial refurb of the PI system it has NEVER let me down.

i think the pi system is a big part of the character of the car and although i love the look of tripple webbers i dont think they are an improvement for the PI cars.

steve

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Hi Nigel

I agree with both Roger and Steve your biggest problem with the Lucas system will be when was it last overhauled?  as ethanol in todays fuel will/would have degraded the seals the bosch /sytec pump modification is probably worth doing  

Chris 

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I'm not a total originally buff but want it look as original as possible so I've made a few compromises to hopefully see improved reliability along the way. I had the PI system refurbished and will run it with a Bosch set up with improved power supply to keep the spirit of the car right.

I will try and hide improvements as much as possible.

As Roger says EFI is cheaper to make and set up now and if it was available back in the 60's I'm sure Triumph would have fitted it to save a few shillings! I'm hoping the Lucas  will be 100% reliable once set up as I can't see why wouldn't be.

Carbs look and sound nice but are arguably more temperamental and difficult to set up and keep on song in the longer term, if they were any better they would still be in mainstream use. Interesting that you can buy carbs with injectors for EFI!

Andy

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The Lucas PI system is not the Achille's heel of the TR6.

It was widely blamed in the day, largely by those who didn't understand it in the service centres.

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I have found in my three years of ownership if it’s PI use it regularly and it’s ace. I make sure I run my car at least every 2 weeks during winter time and the rest of the year it’s used every week. I also make sure the engine is always up to temp in the winter runs.

Edited by Paul Hill
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Pi system is vety reliable even with lucas pump.

It s now 10 years of ownership with a refurbishd fuel system

No issues at all once is afr is setup, wich can be difficult

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The PI can be reliable but does not like being unused. It can be tricky to distinguish PI misbehaviour from ignition faults. I do not like the inbuilt lack of acceleration charge that means cruise mixture must be richer than ideal in order to prevent a lean spike and rattling pistons when flooring the throttle. IF classics are again subjected to emmission tests, SU carbs are easier to  tweak. And can give better mpg, when fuel becomes rationed.....

Peter

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My TR6 CP Pi was off the road for many years...I junked the existing (bosch) pump and fitted a new one and wired it in properly with a solonoid, and had the metering unit and PRV valve and all six injectors refurbished by Raven Smith (many references to him on this forum)

4 years later and 5k miles zero problems and has been totally reliable

 

Edited by jogger321
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I've had my 1970 PI for nearly five years and covered 10,000 miles in city and country driving. Apart from 3 or 4 blocked injectors and a stuck enrichment lever the injection has never been a problem.

The car had covered only 2-3,000 miles in the preceding 25 years so I put the minor problems down to lack of use. I had an injector needing bleeding about 6 months ago and that has been it for about a year.

I now use the car regularly, at least weekly and sometimes all week. No performance issues.

The PI is a bit thirsty, less than 20mpg around town and about 25mpg on a trip out of town. The acceleration is fantastic, the engine is smooth and sounds great.

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Obviously it's your car and you can do what you like to it, but sometimes I'm thinking, (when I've read some posts about upgrades etc) why didn't you just buy a Mazda MX5?

For me the allure of a car is what makes it unique to other classic brands, and a big thing about a TR6 is that in the UK/ Europe, it was petrol injected. So for me personally I would keep the P.I. and just make sure it's in good condition, and then enjoy it. 

Gareth

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A well rebuilt & set-up Lucas PI equipped car, is a very reliable system, despite what people have said in years gone by.  Lucas fuel pumps are also OK, but I have always had Bosch fuel pumps when I ran this system.  Tens of thousands of miles, all over Europe and never any bother, even with temperatures up to 40 degree heat.

 

Cheers.

Edited by TRTOM2498PI
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 I agree with Gareth's comments above, just my personal opinion, and feel free to disagree. I'd also add that in my experience the Lucas system has been reliable, I think the issues with the Lucas pump are overstated. The main problem seems to be modern fuels combined with old seals/diaphragms, overhauled units should be fine.

Mike.

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The problem with the Lucas pump is cavitation in the heat. In Australia it was a major reliability issue for PI cars, especially on hot summer days in traffic.

I have driven my car with a Bosch pump on 44 degC days in Sydney traffic without any issues.

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On 5/5/2021 at 10:15 PM, michaelfinnis said:

 I agree with Gareth's comments above, just my personal opinion, and feel free to disagree. I'd also add that in my experience the Lucas system has been reliable, I think the issues with the Lucas pump are overstated. The main problem seems to be modern fuels combined with old seals/diaphragms, overhauled units should be fine.

Mike.

For those of us who have driven Lucas PI cars since back in the day before leaded fuel disappeared, the issues with the Lucas Pump were present back then. The pump in perfect condition is marginal and minimal can result in cavitation in hot weather. 

I wonder how many are still using the Lucas pump in hot climates?

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29 minutes ago, Andy Moltu said:

For those of us who have driven Lucas PI cars since back in the day before leaded fuel disappeared, the issues with the Lucas Pump were present back then. The pump in perfect condition is marginal and minimal can result in cavitation in hot weather. 

I wonder how many are still using the Lucas pump in hot climates?

One of our members with a TR5 has the Lucas pump. His wife is very adept at pushing the car. In Adelaide for a concours week I had the misfortune to be behind them when the pump decided it was too hot and was going to sleep. Twice.

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My experience is fit and forget after installing a Bosch pump. I realise it will fail the conkers & rivet counters test but to be honest I enjoy driving my TR6 and whilst I recognise its a 50 year old car that will need constant fettling ... worrying about breaking down with an overheating pump/cavitation is one less thing to worry about from my point of view!

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18 minutes ago, jogger321 said:

My experience is fit and forget after installing a Bosch pump. I realise it will fail the conkers & rivet counters test but to be honest I enjoy driving my TR6 and whilst I recognise its a 50 year old car that will need constant fettling ... worrying about breaking down with an overheating pump/cavitation is one less thing to worry about from my point of view!

Agreed. 

 

The 'correct' PI set up is always going to be something of a compromise but when it is right, it is great. 

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