Cold running and why tuned Minis simply quit running when pulling up.

Winter is coming, and with it various issues that affect Minis used throughout the year, no matter what the conditions.

This month's consideration is cold running and why a plethora of tuned Minis simply quit running when pulling up. Ignoring the few that are down to various other ailments, the main issue is just the cold weather. Those that suffer more than most are those with tuned engines with aftermarket manifolding, exhausts and air filters. The standard OE set-up ensures a warm air supply to the carb until the engine has warmed up sufficiently then diverts cooler air in.

Trashing the standard air filter in favour of a freer flowing, better looking, less space consuming (or whatever reason replacement is deemed necessary) after-market unit looses that initial (and extended in the case of really cold weather) warm air facility. The odd one or two companies offer warm air induction kits to help correct the balance when needed. But even these do not conquer carb freezing in very cold or cold/wet weather. There are things that can though…

If you have an ally inlet manifold with a water-heating facility - generally a pipe sticking out of each side of the manifold - then connect this up. Take a hose from the heater tap or heater tap take off point on the right hand end of the head and connect it to the right side of the manifold, then take a hose from the left side of the manifold in to your heater feed pipe. Usually you can use the existing pipe from the heater tap to the left side of the carb, then get a short piece of hose to connect the right side to the heater tap. Check the hose and pipe sizes though as some have different fitting sizes. If adaptation looks necessary from one size to another - your local auto-factor should be able to help. Gates (as in cam belts and general auto hosing) do some brilliant and really useful water pipe adaptors.

Fit the next warmer running spark plugs from those fitted. Being a fan of NGK I use BP5ES in place of BP6ES (most standard-ish fitments and mildly tuned motors), BP6ES in place of BP7ES (fairly modified motors with higher compression ratios in the order of 10.5-1 or more) and BP7ES in place of BP8ES (seriously modded motors with high compression ratios). You'd be surprised how much difference this will make.

Make sure a decent set of spark plug and coil HT leads are fitted. Dodgey, ancient HT leads can cause severe resistance dramatically reducing the firepower of your spark plugs. You don't need anything fancy. Those super-sonic, mega-buck 8 or 10mm 'performance' leads are a waste of money since all that 'size' thing is merely there for heat protection - not an issue in a Mini! They are still generally only carbon-string cored leads. I favour the Lucas 'Speedline' leads. Cheap and exemplary service.