How do you exactly adjust mixture with the 3mm key?

[Stringer]

I'm just about to try making my adjustment a bit leaner, as after replacing a lot of parts, i have noticed it's still running a bit rich - but am concerned about pushing the key in too far, which i understand is like falling into the abys.

How far DOWN do i have to push to SAFELY engage the screw before turning it?
Can someone let me know?

thank you

 

[V12]

It's easy to feel it engaging, about 5-10mm down from memory. Never had an issue with pushing it in too far before?

 

[jaymanek]

I hope you have an accurate gas analyser and you are not just trying to do this by smelling the fumes!?

 

[V12]

Too true. Was adjusting a 420 v8 last week on a small blue point analyser that zeroed ok, but then went crazy when we put it up the pipe?! Took it round to a friendly mot station, Their analyser was much better!

Sent from my GT-I9300 using MBClub UK

 

[Stringer]

actually i heard/read many reports from people who said that if you push it down too far, it buggers it up entirely.
I was, yes, planning to turn it a quarter turn ccw to make it a little lean - and run it for a few days like that. How can that be so risky?

 

[mazza]

actually i heard/read many reports from people who said that if you push it down too far, it buggers it up entirely.
I was, yes, planning to turn it a quarter turn ccw to make it a little lean - and run it for a few days like that. How can that be so risky?

Hello mate

its a bit of a "Guess work" operation mate!

have you taken a CO reading recently?

a quarter turn will have a huge effect on the mixture, you may find that you will lean it too much and you will experience cold start problems.

an engine running lean is a NO GO..its better to run it rich.

my advice is...leave it alone until you get your hands on a CO meter and then perform the CO adjustment properly.

all the best

mazza

 

[Stringer]

hello mazza
i will take your advice, for sure. Don't fancy cracking a piston. But where the dickens can you find a co2 meter and are they cheap? I am about to install a o2 sensor in the downpipe (the last owner pulled it out and used it as a bricklayer's weight). Is there a way of using the electrical output from the sensor to make such adjustments?
ok ok thats five pints i owe you now
M

 

[mazza]

hello mazza
i will take your advice, for sure. Don't fancy cracking a piston. But where the dickens can you find a co2 meter and are they cheap? I am about to install a o2 sensor in the downpipe (the last owner pulled it out and used it as a bricklayer's weight). Is there a way of using the electrical output from the sensor to make such adjustments?
ok ok thats five pints i owe you now
M

Hi Stringer

I used "Gunsons" Gastester, these are pretty good and do the job.

here's one for sale on ebay
Gunsons Gastester | eBay

Its easier if you fit a permanent lambda + AFR GAUGE. There's plenty of these combos available from tuning equipment manufacturers. I use INNOVATE motorsports, its a very very good product.

hope this helps

mazza

 

[spanner]

If you've got a "later" car with cat/O2 sensor then you really shouldn't bother playing with it at all as the whole system is compromised by the removal of the O2 sensor.

 

[Stringer]

so in other words put back the new 02 sensor and hope that this 'adjusts' the mixture?
(it's an old on, eh? 1987 but it used to have an o2 sensor as the wiring is all there under the mat) thanks