Has anyone used a Gunson's Digital Gastester for setting up mixtures? It's a CO meter which measures CO content in your exhaust pipe, not hydrocarbons. By adjusting the CO% within the correct range of 3.5 - 4.5%, you can set the air/fuel ration at idle (around 14.7:1 for a standard engine). More accurate than Colourtune.

There are a number of exhaust gas analyser devices available that measure CO2, and other gases, as well as CO, but they cost over $3000. Gunsons costs around UKP75 in the UK.

http://www.autoexpertproducts.com/Gasinfo.htm

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

testing CO% is the 'old' way to test your mixtures, I've been playing with one of these the last few days - fantastic

http://www.innovatemotorsports.com/products/lm2.php

I haven't tried one but did look at these a little while ago. For basic tune up stuff, these would be quote OK, but if you're trying to sort out needles etc because of engine modifications, then it won't cut the mustard.

Don't be too quick to write off colourtune. These are very good.

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The inovate unit that Simon is talking about are pretty reasonably priced. We have an LM2 and it was $600. And you can log more than just CO% with it. You can also log Vac, tacho, brakes..... basically anything you can fit a sensor to.

I think (could be wrong but can go check) something like 10 different inputs.

Pretty good value for money. It records it all to an SD card and you can lay it all out in the program and play your run in real time.

EDIT> Just checked the price on Simons link.... ours was the second kit mentioned... looks like they've come down in price (unless that is a USD price)

If that's too dear the LM1 is still available (cheaper), from Titan Motorsports I think. They work good, GR and Greig Malaure both have one.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.