The Triumph 2000 / 2500 / 2·5 Register Forum

I'm starting the restoration of my Mk1 PI (The White Elephant) and in amongst a shed-load of bits I bought was an original Mk1 fuel pump/swirl pot bracket with the swirl pot in situ. I'd never seen one of these before! This has got me thinking about whether I should try to preserve the old car in its original spec, rather than going down the Bosch route. I do want to use her on occasional runs to work though, so reliability is a consideration (although not up to a daily driver level).

Am I wasting my time with a Lucas pump?! I'd be interested to hear thoughts. I have a Lucas pump reconditioned within recent memory and fitted with a cooling coil which I'd use, and would obviously check the supply wire and run a thicker one via a relay if necessary.

Is anyone still running a Mk1 PI with a swirl pot? I see that the original set-up had a bog-standard low-flow fuel filter, which I assume would be better replaced with a CAV filter/housing like the Mk2s. Does the swirl pot set-up work OK, or is it best left in the shed?!

Thanks all for your injection of ideas (see what I did there...).

Jonathan

Hi Jonno

surely you got along way to go before thinking about this.....

Presume the bits were off my other PI previous owner?.................he will tell you that nothing wrong with original set up and his old PI ( my new one ) as the swirlpot etc...............

Also a Slate Grey Mk1 I bought had this set up but I never actually had the car running,nor the new one so can't really comment whether should keep standard or not.

However, freinds swear by the original set up..........

So down to personal choice I suppose but I am going to keep my new one original and that is to be used everyday. The other Pi as the Prestige development set up and the only problems that I have encountered with this is when I have been towing my classic caravan in hot weather and was caught up in traffic.
When is the White Elephant off to TRE?................mine will be on the road pretty soon. Awaiting paint,exhaust and battery.....................

Good luck...............ps you haven't any spare Sports Exhausts knocking about in the bits have you?

Proper can of worms there Jonno!
I run my mk2 pi with the original Lucas pump and without a cooling coil, I have never had a problem with it. I did however do the relay feed thing and proved that without, the pump had a 10.27v feed and 12.9v with it. A poor voltage to the pump will make it overheat for sure.

Colin.

What do you run on the rally pi?

Assuming that it is in a good state of repair and adjustment, IMHO the Lucas pump is up to the job. Many of the problems encountered in the Triumph application can be attributed to inadequate electrical and fuel supplies. Bosch can provide a perfectly usable alternative, but only if you can be sure that all supply issues have been addressed (extra-important as Bosch requires even greater fuel flow and electrical current than Lucas). Personal opinion again, but I reckon a direct electrical feed via fuse and relay (using the original circuit through the inertia switch to control the relay) is essential, along with ensuring that you have no kinks or restrictions in the supply line from tank to pump (watch out for original nylon tubing shrinking over time).

The little in-line filter used on the original 2.5PI saloon was not really adequate for the amount of fuel needing to be passed and may have been replaced by the bigger CAV filter even before the end of Mk1 production. Another possibility might be a present-day ‘bullet’ filter or the larger in-line type used on some later fuel-injected vehicles (1980s Jaguar XJ, Range Rover EFI, etc).

Most of my experience has been with the Mk2 set-up, I’m afraid, but I think that I’m correct in saying that a lot of the difficulties with the Mk1 swirl pot related to the pump pulling air through the tank breather under low fuel conditions or hard cornering. There was an excellent article on the development of the PI system published in Six Appeal (MH Evans, April 1990) in which the author described curing Mk1 saloon fuel surge problems by replacing the in-line filter with the CAV version, retaining the swirl pot but putting a restrictor in the vent pipe between swirl pot and tank to stop things from flowing the wrong way.

You can, of course, eliminate the swirl pot completely in favour of the standard Mk2 set-up (or a Bosch conversion) but, if you do, remember that most (all?) original Mk1 PI tanks lack the anti-surge reservoir fitted to Mk2 versions, which may once again result in pump starvation at low fuel levels, on hills or under spirited cornering.

The rally PI is a different beast altogether - at 180 bhp, the engine is not quite as standard as the other PI! When I bought it, it had a wheezing Lucas pump fitted - once I got the works-type fuel pressure gauge working properly (there's another thread on that problem I see!), I realised how far the fuel pressure was dropping under load! So the rally car has a full-house Prestige set up in the boot (on the right-hand side so it doesn't get cooked by the exhaust), together with a spare set plumbed in and ready to go! You can never have too many pumps and filters...

It sounds as though I should try and stick with the original Lucas set-up for the non-rally PI with its mere 132 bhp - that will save me a few quid as I have all the bits in stock!

I was going to ask about issues with the filter and swirl pot, but it looks as though Jonathan has already answered these. I was hoping to keep the filtration under the floor as per the original Mk1 set up (the Mk2 CAV filter is on the wheelarch isn't it?), so maybe I'll look into a modern high-blow billet filter (may be going back to Prestige after all!) and a one-way restrictor.

Thanks for your help so far!

Jonno

Just a note that the restrictor mentioned in the Evans article was to reduce the internal diameter of the breather in order that 'its maximum rate of passing air was greatly reduced'. By a one-way restrictor, if you mean one of those flap-valve devices, that could well work providing that the effort needed to open the valve when passing from swirl pot to tank is negligible - if not, I can see possible problems with the pot not being able to purge itself of air/vapour especially if the level of fuel in the tank is low.

Good luck with whatever you try!

Bosch is not more reliable. I use a later ( swirlpot ) tank and have no real issues with the Lucas set up on my Mk1; it can be injectors / fuel surge / heat / volts; a dashboard pressure gauge gives peace of mind. But as the first, in 1992? to fit a Facet feeder pump .... that is highly recommended.