Heuer wrote: ↑Thu Apr 18, 2019 10:50 am
"adding a filter king could actually introduce problems because it could affect the flow rate"
Careful – the words ‘hoist’ and ‘petard’ are in floating in the ether

.The above statement looks correct to me, but no, I won't duke it out on Saturday, especially as you're a gun expert as well.
The risk of introducing problems would be true if the F-King gadget were a no movable parts, sealed-for-life mechanism, on the basis that in at least one respect the more components there are in a system, the greater the cumulative probability of a failure occurring. In practice, the F-King thing
does have movable parts and is
not sealed for life. It therefore adds the twin potential failure modes of human error, like pressure maladjustment or failure to attend to a clogged filter (possibly invisible) - and materials failure: e.g. bowl gasket problems.
You could quite reasonably counter by saying you were assuming the F-King regulator would be in good working order and performing to spec, otherwise its use would not be expected to be up to par. But then this whole thread is predicated on the assumption that something was wrong or out of spec with your car that required a F-King fix. I think this is far from proven, although I totally accept your 2008 account (which I’ve seen for the first time here) as being an accurate record of what you observed with your car.
Heuer wrote: ↑Thu Apr 18, 2019 10:50 am
After 45,000 miles with the Filter King I can testify there are no such problems.”
That is excellent news but irretrievably anecdotal in the big picture. To most of us the only car that matters is our own, but we must concede that absence of evidence in our tiny samples is not the same as evidence of absence overall.
Heuer wrote: ↑Thu Apr 18, 2019 10:50 am
I would be interested to know how many miles of testing they did to come up with that statement.
Possibly more than the number of cars you have tested my good friend. I would expect the exclusive global source of SU pumps and carbs to hear enquiries occasionally from people having problems with non-standard fuel systems. I would not be at all surprised if, after taking a full history, those customers were advised to replace all non-standard parts, to at least achieve a baseline from which Burlens, as maker of all the bits involved, could then solve any mystery. I would anticipate that in many cases the mere act of returning to standard spec would clear up a proportion of the problems. Which brings us to the elephant in the front room of your beautiful Nottinghamshire home David – the issue of probabilities.
From your initial 2008 thread, and subsequent comments, you seem to be saying that there is an inherent risk/flaw in running as A-series SU fuel pump with SU carbs, unless an accessory fuel pressure regulator is interposed. I may have got that wrong.
The fact that no carburetor 6 Cyl Jag ever came with and FPR (as far as I know) and that millions of British cars left their factories also without external regulation cannot be ignored, surely? SU made the pumps and the carbs to work in unison, and they do that without any extra tech. The range of pump pressure produced and the range of pressures which the float valve is capable of sealing, overlap sufficiently to work as designed. The fact that your car responded to the mod doesn’t prove the SU pump and three toilet cisterns are mismatched, it suggests something else was wrong. The fact that 45,000 miles later everything is still working well also says nothing about pump and carb compatibility except the Malpassi is almost certainly not harmful.
Angus said he will hold our jackets...
