14 replies to this topic

[corrado vr6]

So the mini had its first MOT after hibernating for a while, sadly failed on emissions.

https://www.dropbox....ayavih09p3&dl=0


Engine is 1330cc Hif44 carb. Carb was reconditioned not to long ago. Hopefully it’s just some settings adjustments but a bit lost as to where to go except a tune up really.
I thought maybe the mixture but reading posts that that is just the idle mix and fuelling is done with the needle.

Need to find an old school garage in Winchester Hampshire 🙏

[nicklouse]

Have you had it tuned by someone who knows what they are doing with an SU carb yet?

[Lplus]

So the mini had its first MOT after hibernating for a while, sadly failed on emissions.

https://www.dropbox....ayavih09p3&dl=0


Engine is 1330cc Hif44 carb. Carb was reconditioned not to long ago. Hopefully it’s just some settings adjustments but a bit lost as to where to go except a tune up really.
I thought maybe the mixture but reading posts that that is just the idle mix and fuelling is done with the needle.

Need to find an old school garage in Winchester Hampshire

That test is done at idle.  The idle adjustment is on the carb body.

[Designer]

Hi

 

Via the M3 and A36 A C Dodds in Salisbury is only 45.mins to 1 hour away from you. I would love to get my Mini tuned by him but I am too far away.

I understand he is the Bees Knees, King of the Tops when it comes to tuning Minis . You can private message him on here.

 

Paddy

[absx2]

Quarter of a turn anti clockwise would probably have fixed that during the MOT test.

The old skills are truly being lost when a quick turn of a screw is considered more difficult than plugging in a computer.

 

I had a time served Ford technician come to me to replace his points ! 

[Cooperman]

It's a real problem getting the emissions right with a Mini with a carb.

Even when accurately set up by a professional the figures can still be way too high.

The best advice is to set the tick-over to around 1200 rpm, then weaken off the mixture until the engine will just run, remembering how many turns you have weakened the mixture screw by so that you can re-set it later. You may have to alter the ignition timing, although this is not usually necessary. If that doesn't work, increase the tick-over a bit more to, say, 1400 rpm.

[68+86auto]

It's easy to get that to pass emissions.

 

If you were to just lean the mixture out a little bit (perfectly fine to adjust) the CO will be within limits easily. Your HC reading is way higher than it should be, I'd expect under 200ppm even though the limit is 1200ppm. HC is basically unburnt fuel, here are some possible causes:

 

 o Ignition system failures

                        -incomplete combustion due to fouled spark plugs

                        -improper timing or dwell

                        -damaged ignition wires

                        -faulty ignition secondary component

                        -faulty individual primary circuit on distributorless ignition system

                        -weak coil output due to coil or primary circuit problem

            o Excessively lean air/fuel mixture

                        -Vacuum leaks

                        - leaky intake manifold gasket

                        - worn throttle shaft

            o Exhaust leakage past exhaust valve(s)

                        - tight valve clearances

                        - burned valve or seat

            o Incorrect spark timing

                        - incorrect initial timing

                        - worn piston rings or cylinder walls

            o Insufficient cylinder compression

            o Carbon deposits on intake valves

[timmy850]

You shouldn't need to adjust it to pass MOT. It should be set up correctly with the right ignition system to fire lean mixtures, and the carb fueling should be set up to pass emissions and also provide proper fueling across the rpm and load range. 

[ACDodd]

Timmy850 has it correct.

Ac

[Ethel]

Simple things can make a difference, such as a new air filter & oil change.

 

...or a loose breather hose 

[corrado vr6]

Forgot to add

Oil and filter is new
New spark plugs
New ht leads
New points, condenser
Tappets gapped
New coil

Just leaves timing and the mixture then, it runs nicely as is but wouldn’t have been very hot as the MOT station is very local

[corrado vr6]

Update

Today I was able to borrow some tools, so I have now adjusted the dwell angle using a dwell meter. I set the timing using a timing light and lastly I was able to borrow a blue point gas analyser so I could adjust the mixture to get the CO down within the limits.

Hopefully it should be all good. Runs so much better in the lower rpm’s now

[corrado vr6]

Final update - MOT passed with
0.2 CO
710 ppm

At least I now know the 80’s blue point gas analyser is working

[cal844]

Final update - MOT passed with
0.2 CO
710 ppm

At least I now know the 80’s blue point gas analyser is working

Well done on the pass

[68+86auto]

Final update - MOT passed with
0.2 CO
710 ppm

At least I now know the 80’s blue point gas analyser is working

 

It still looks like you have an issue that needs to be sorted. Don't ignore it, you will probably be amazed once it's fixed.

Edited by 68+86auto, 18 July 2024 - 12:15 PM.