CALVER'S COLUMN  

 CALVER'S COLUMN  

 
Calver's Column 
 
This is a section that deals with short comments clearing up issues that crop up either in the press or on the internet/forums where technical blunders are made – like calling dampers (the gas/oil filled tubes that resemble bicycle tyre pumps at each corner of the car that stop it po-go-ing down the road over bumps) 'shock absorbers'. Shock absorbers are the main suspension springs – so the rubber springs on the Mini as standard. And I suppose to a certain extent the tyres. But technically the springs. 
 
 
STAGE ONE FUELLING KIT ERRORS 
 
I have seen in various places, both in print and on line, some confusion from folks having bought stage one kits in that having fitted said kit, their Minis performance is noticeably worse than before it was fitted. In a majority of cases it seems that these Minis are suddenly incapable of acceleration, and can barely make 50 mph. 
 
The advice given by those supposedly in the know tends to revolve around looking for air leaks and recommendations that once fitted stage one kits need setting up on a rolling road. The significant omission by said folks is that any properly developed stage one kit should have been thoroughly tested on a variety of cars to establish a suitable carburettor needle to correct fuelling, and a revised ignition setting. Both should enable the car to be driven normally and experience the performance improvements the fitting of such kits should provide. Otherwise – what's the point? 
 
The other fact not aired is that in a majority of cases where this performance loss occurs, it is because the vendor has not actually developed the kit, simply copied one done by another company. And to make matters worse, they introduce different components to that used in that already proven kit. Consequently the fuelling and ignition settings required are going to be very different. 
 
The most glaring example of this was, following the release of the first stage one kit post Abingdon Special Tuning days by Mini Spares for the 998 Mini, was a similar kit released by another Mini specialist who simply copied the kit. 
 
Except for one massive change – the use of a K&N cone replacement filter instead of the K&N element in the plastic casing the kit was originally developed to use. Consequently, the 'copied' carb needle supplied by this other company was nothing like what was needed to make the engine perform properly. So before ordering a stage one kit, ask if it has been properly developed, and comes complete with suitable carb needle and ignition settings. 
 
Whilst both may not be exactly what your particular engine needs to produce the absolute best, it should be pretty damned close. 
SPI/CARB CONVERSION PERFORMANCE CONFUSION 
 
I recently witnessed yet more bum information being handed out to Mini enthusiasts concerning the possibility and likely outcome of converting single point injection induction systems being swapped for a carburettor set-up, the statement made that there is no real gain in performance and there will be issues with emissions, ECU and wiring. Obviously the expert, or specialist, concerned has not actually attempted the conversion. 
 
Many issues back now, issue 114 in Winter 2005, I did this very conversion to see what would happen. In the article I listed all the parts needed to do the swap, exactly how to go about doing it, and then recorded the results on performance for posterity. A new fuel pump is needed as the standard injection one is far too powerful for a carburettor, even that was easy with no problems leaving the in-tank fitted injection pump where it was. I tested the car before the conversion on a rolling road, did the conversion, then put it back on the same rolling road on the same day. In fact the conversion took barely an hour and a half from memory so was a perfect comparison. 
 
Nothing fancy or clever was needed doing with the ECU or electrics as the ECU still ran the ignition side of things. The car used gave performance figures commensurate with every other standard equipment SPi we had had on it. The end result was a positive 10% gain everywhere in performance with the carb fitted. Out on the road, the car was used for a week to see what the fuel consumption figures were like in comparison too. The result there was an improvement to the tune of around 8% over all. 
 
Following that article, a number of Mini SPi owners carried out the same conversion exactly as reported, and were pleased to report the same performance improvements were achieved – so it was not a one-off. 
 
The rolling road test results were: 
MPH BHP SPi BHP carb 
30 13.0 14.6 
40 19.0 21.7 
50 26.1 28.5 
60 30.0 33.6 
70 33.0 36.8 
80 41.7 43.6 
90 41.6 46.0 
 
OIL PUMPS 
 
Despite what has recently appeared in several articles in the tech section on various folks Minis in the specialist press – there is no such thing as a 'high pressure' oil pump for the A-series. The pressure is entirely a feature of what rate spring is in the oil pressure relief valve and what clearances there are between crankshaft and main and big end bearings. Providing there isn't some other issue like leaking oil gallery plugs or such.