Gunstons Gas Tester Mk2 - help

[akku]

I bought one of these of eBay and went to use it and guess what, no instructions, so I made a few guesses as which pipe went where but what ever I seem to do it just reads 2% which is "spot on" according to the gauge. I know for a fact thats not right 'cos the plugs are black as a miners hat.

Anyone like to suggest how the connections are supposed to be and what I might be doing wrong or have I just bought a duff one?

[rustingdeathtrap]

How many cars have you tried it on? Might be best to see what it reads on a modern cat equiped motor then get yours as near to that as you can.

[PhoenixC]

You need to calibrate it before putting the pipe in the exhaust. The machine should be connected for a couple of minutes before you start to calibrate, wait until the readout stays steady for a few seconds.
One other point to note is that you cant rev the engine with these just keep it on idle otherwise you will blow the diaphram.

[akku]

OK I did the thing to just let it breath normal air. Needle seemed steady so I connected it to the tailpipe at a reasonable idle with the motor warmed up. I haven't tried it on another car, I'll pop it on the Toymota and see what it does. I presume oe pipe connectes from tailpipe to the centre of the disc bit and one pipe comes from the top of the disc bit to the back of the square bit. That right?

Needle doesn't seem to move from 2 whether its in fresh air or up the tail pipe same reading.

[mattblack]

Is it the one that does dwell, volts ect as well? I've got one of those, PM me your address and I'll send you a copy of the instructions if you want...

[akku]

Nope, it just hooks up to the exhaust and uses the battery for power (although the Oldsmobile is too long for the leads to reach so I ran it of the Buick battry!)

like this (if the photo works)

[mattblack]

Mine's the later one with the digital read out, you've got the 'retro' version... ;D

You do have to patient with them, they take a while to react to you adjusting the carb...

[Mr K]

Plugs will be black if you havent done any long journeys, they need to get up to temprature ect properly to see what they are doing.

[akku]

Maybe I'm being impatient. I might go put it on my mates MOT emissions tester for a laugh.

Its done a mixture of long an short journeys. At one point I was doing 80 miles a day all down A roads, not hanging about.

I never have seen plugs as bad as these first time I pulled them out. One electrode was actually closed up with soot and was not firing at all...

I've tuned it by ear and nose and its not making black soot balls when it starts up now so we'll see if the plugs are looking any better in a couple of weeks.

would like to get this gastester working though.

[mattblack]

TBH It would be worth getting in touch with Gunson's... They replaced my gastester when it went wrong, I found them very helpful...

[akku]

was yours like 20 years old and you got it off eBay though?

[dave364634]

whats it suppose to run at (we're talking CO% yeah?)?

some 60's stuff (vanden plas etc) runs at 10%CO on idle but, goes down on fast idle. toymota should read 0-0.20% assuming its got a cat.

[akku]

Its the Oldsmobile. The needle just didn't seem to move.

The Toy has a cat as its a '95 model.

[mattblack]

alistairk said:

was yours like 20 years old and you got it off eBay though?

...no, but I wasn't suggesting that they'd replace yours... but they might send you some instructions...

[celicaV8]

Try this:

Instructions

[akku]

cheers all.

[Mr_Bo11ox]

One method I have successfully used for checking the mixture, is to shut myself in the garage with the engine running and time how long it takes for my vision to go blurry.

4 minutes = Too rich, 8 minutes = too lean, 6 minutes = about right.