I've recently purchased a 1972 1275 GT, which runs pretty well but has the following problems:
1) When I first got the car it would stall immediately at normal operating temperature unless run with the choke approx 3/4 inch out. I took it to a local garage who told me it was running too lean, so they richened it up and reset the idle speed. They (MG specialists so presumably familiar with Mini engines) thought it might have an aftermarket cam fitted as the engine pulls very strongly at higher rpm. I've now wired up the rev counter, which shows the car sometimes idles OK at 750rpm with the choke fully in, but more often than not will stall unless idle speed is raised to about 1000rpm, particularly when coming to a standstill at junctions. Would an aftermarket cam alone explain the above? 1000rpm seems a bit high to me.2) The car misfires/exhaust pops noticeably above 4000rpm. Below
4000rpm it seems OK, there is a slight chug from the exhaust at idle and an occasional pop on the overrun. The exhaust is the straight through, large bore type with twin centre exit. I've got a 998cc Mini with the same exhaust which doesn't pop on the overrun so I'm guessing this isn't normal.3) There is a strong smell of fuel in the cabin after approx 5 minutes of running. It seems to be coming from the carb and gets noticeably stronger after hard acceleration. I've had the car idling with the bonnet up and can't see any evidence of a fuel/vacuum leak.
4) Fuel consumption seems a bit high. I put nearly a full tank of fuel in on Friday evening (=A315) and have done approx 60 miles of mixed driving since. The gauge now reads 1/4 full, which I make just over 30 mpg. Maybe I'm optimistic but I was expecting closer to 40mpg - my Mini 1000 will do well over 40mpg under normal use. The exhaust tailpipes are quite sooty, if the mixture had not been checked so recently I'd wonder if it was set too rich.5) The throttle has stuck part way open a couple of times (dabbing the accelerator once or twice unsticks it). Is this down to a sticking needle in the carb?
In the fault finding section of my Haynes manual, problems (1), (2) and (3) have a flooded float chamber on the carb / incorrect float height listed as being a possible cause.
I'm thinking about removing the carb and servicing it. Sound like a good idea? All suggestions appreciated.
TIA