checking mixture co2 reading on gas analyser

[xpress]

i have the use of an old hawk gas analyser, has anyone used one of these old hawk gas analysers? not sure if i have to leave it in the exhaust there for a while for it to warm up and get a good reading. any quirks with them, or a procedure to follow? what sort of mixture reading should i be getting?

do you think that a poorly charged battery would affect unburnt fuel/mixture?

[bmcecosse]

Just twiddle mix and timing for smoothest idle - then look at the plugs after a good hard run.

[dalebrignall]

i use a gunstons colour tune they are simple and work well .

[chrisd87]

I've got a Gunson's Gastester (which is a CO meter). I'm not familiar with the Hawk analyser but I presume that you'd need to calibrate it before use. In the case of the Gunson's Gastester, that consists of leaving it to warm up for 15 mins with the probe in the normal atmosphere (i.e. not next to a running car), and then setting the CO level to 2%. It's then ready to use. On a Minor you're looking for a CO value in the region of 4-4.5%, but seeing as there's no MOT emissions test to pass you'd do just as well to look at the colour of the plugs.

As long as the car is running, the condition of the battery should be immaterial.

[pegasus]

i used to have a gunsons gas tester, they are very good but i found the hawk to be a better built machine. My hawk is a model 766 is it the same as yours?
If it is i have the original instructions for it, i can scan them in over the week end and send them in a pm if you want.
Mark

[xpress]

thanks pegasus, i think i have the same one. in shorthand, is there a setting to set it to 2% for calibration then what do you expect it to read ideally? 4/4.5%? do you tweak the mixture until that is achieved? cheers.

[bmcecosse]

Just take the car for a decent out-of-town run of say 10 miles. Switch off before coming back into traffic - pull the plugs - what colour are they? No need for meters.......

[pegasus]

Not really quick or practical to go on a run, pull plugs adjust and run again, pull plugs ect untill its right. If you have a tester use it, the coloutune is quite good, and so are the gunsons co meters.
For the Hawk make shure the needle is zeroed while the meter is cold. Then with a warmed up engine on idle connect the hawk to the battery, flick the test switch and the needle will move to show that the power is going through, put the test switch back. Allow the Hawk to warm up for 1 minute. Adjust the balance knob untill the needle is on the balance line on the dial. Put the pick up tube in the exhaust and read when the needle steadys, 4 - 4.5% is right.
Mark

[bmcecosse]

These meters only tell the idling mixture - which anyone with an ear (and a finger) can set on an SU carb engine....... The IMPORTANT thing is the running mixture! Hence the v important plug check.

[xpress]

doesn't the gunson one check the mixture while running? if you set the idling mix right, surely, unless there are any problems along the way, (timing, ignition problems), the running mix should be right?

[bmcecosse]

If it's battery powered - you can try! And no - the idling mix can have absolutely no relation to the running mix............

[xpress]

I would say though, that the idle mix is important in city in that you can get through a fair bit of fuel idling especially if running rich!

[xpress]

Wouldn't you be able to check mixture across rev range like with variable ignition timing?

[pegasus]

The Hawk can still be connected while the car is being driven, this is why the pick up module can be attatched to the bumper.
The tests that can be done with this unit, for both petrol and lpg are
carburettor idling test,
High speed test,
Accelerator pump test,
Carbon monoxide test.
Unfortunately i am missing a couple of pages of the manual, so i`me off to try and find them now.

[xpress]

good stuff pegasus. i suppose there's little tinkering you can do with the vaccuum advance, you can only tell if it's running right or not.

[MarkyB]

the idling mix can have absolutely no relation to the running mix

Are you saying that the lift pin method is invalid, or talking about fitting different needles?

[bmcecosse]

The lift pin is perfect for setting the idle mixture......

[MarkyB]

So they picked the original needle in a lottery?

[pegasus]

I have found the missing pages, they had dropped out in the box (i still have the original box too). After trawling the internet i think i have the only set of instructions left in existence. I have a few things to do then i will scan them and send them to you in a pm. It will explain in more detail how to do the diffrent tests.
Mark

[xpress]

lol cheers peg. that would be great.

aside from visual tests such as black soot from the exhaust and spark plug reading, i think a gas analyser is a handy tool!