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 (£15) 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

hello TIA

problems 1-3 will really only be sorted out by a good rolling road session,
perhaps a couple of hours worth. If you are anywhere near lincoln, i would
recommend looking up mick barratt engineering. There are so many settings
to play with, you will be years doing it without a rolling road and a
knowledgeable operator. Wtih a 1275 gt with different cam, you will really
see the changes i am sure.

Leaning / richening off the fuel as the MG specialists did is not all your
engine needs (this isnt rimmer bros at lincoln is it...?) ! let us know
where you are in the country and im sure someone will suggest a
mini-friendly rolling road garage.

problem 4 - fuel consumption, - if your calculations of 30mpg are correct, i
think this is about correct for what sounds like your driving style and that
engine if it does have different cam etc. Consumption sould improve with
the above mentioned rolling road session, and reduce the soot on exhausts
etc. - just did some of my own calcs, and working with 82p per litre i make
20mpg, which is a little low. saying this, all the calcs are oly being based
on having 1/4 tank left - mini petrol gauges are notoriously bad.

5 - stuck throttle, most likely to be a frayed cable at the carb end? - have
a look, mostly the 'frays' enter the cable and obviously get caught and dont
release etc.

hth.
RS

"whawes" <wdhawes (AT) gmail (DOT) com> wrote

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 (£15) 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

5. Sticky throttle

I had this for a while. I replaced the inner and outer throttle cable
complete - but within 2 months - sticky again.

The solution was to replace the engine earth strap with a new one - and
I also added a second.

If the earth strap isn't working properly, the engine uses the throttle
cable (and also the heater cable) as a supplementary earth. I replaced
the earth(s) and the third cable is lasting quite well.

This advice came from anoter Mini forum and whilst I was sceptical
initially, it worked.

The advice was also to oil the earth strap before fitting it. Not sure
why...? Possibly to inhibit rust?

Also, my engine wouldn't idle very well. Sometimes it would be OK (c.
700 RPM) Then it would stall at every set of traffice lights -
particularly bad when the headlights (especially high beam) were on.
This didn't happen consistently, it was intermitant. I thought it was
related to wet weather, but since I replaced the earth strap it seems
to idle more regularly. I need to replace the battery earth also, as
this could be part of the story?

Hope helpful

Peter

RS wrote:

whawes wrote:
ID have a very good look for air leaks anywhere on the inlet of the
engine. check all the crank case breathers the carb mounting to the
manifold and that the manifold to engine nuts are tight.


-anthony

air leak in the manifold would be my guess. Remove the manifold and fit a
new gasket and also check the carb seals/gaskets whilst at it as its easy to
replace them while the carbs are off.
"whawes" <wdhawes (AT) gmail (DOT) com> wrote

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 (£15) 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

"Tim" <tim_lis(NOSPAM)@clear.net.nz> wrote


One quick method to check if the inlet manifold is leaking is to spray WD40,
or equivalent water repellant spray, around the manifold while the engine is
running. It doesn't burn so the engine revs will drop if it is entrained
into the fuel mixture.

GrahamL