[quote="Jonathan Lewis"]If wanting to migrate away from Lucas, I think that your options are largely restricted to Bosch or one of the generic replacements (Sytec?). Some research a few years back found suggestions of a Pierburg unit capable of maintaining the pressures and flow rates demanded by the Lucas PI system, but I was never able to identify a definite part number or fitment application, so unsure whether it was a series production unit or a competition 'special'.
One thing to bear in mind is that to do a proper job on a Bosch conversion, you really need to uprate the electrical feed and earth and ideally the internal diameter of the fuel supply pipe as well, all measures that will benefit the original Lucas pump. Also, the set-up fitted to the earlier (late '68 - early '69) Mk1 PI saloons with the small in-line filter and large round surge tank in the boot is apparently not altogether ideal, as the filter is prone to premature clogging-up and the surge tank can sometimes draw air through the return pipe to the fuel tank inlet (i.e. breathing the wrong way). There was an excellent article on the PI system published in Six Appeal
close on 30 years ago (but, I think, reprinted a few years back) which I seem to remember suggested replacing the small in-line filter with one of the larger CAV assemblies fitted to late Mk1 and all Mk2 PIs, and restricting the bore of the surge-tank-to-fuel-tank return pipe to discourage it from allowing the pump to suck air.
Another possibility is fitting a low-pressure high-volume booster pump between tank outlet and filter to help ensure that the CAV filter head and pump inlet are always fully primed with fuel. A heat shield above the exhaust box to keep temperatures down is also a good idea (or even resituating the pump to the cooler right-hand side of the boot, though the latter obviously requires the use of proper high-pressure lines with nut-and-nipple unions in the interests of safety).[/quote
Thanks Jonathan for a very helpful reply. My Mk1 Pi is an early one with the surge tank (or swirl pot as most people seem to call them?) and the inline filter mounted up on the inside of the rear wing. (although is soon to be changed)
After test driving the car for a few days now, my issues seem to be solely with my refurbed Lucas pump. Since changing to another one things have been fine.
However, I will still be looking at possible alternatives in the mean time.
1968 Mk1 2600 Saloon in Slate Grey. (the infamous 'Gertie')
1969 Mk1 2.5 Pi in White http://kingratracing.blogspot.com/