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gunsons colortune

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Never used one, but I'm told that the modern fuel additives may make it hard to read the color.
 
Trevor Jessie said:
Never used one, but I'm told that the modern fuel additives may make it hard to read the color.
Click to expand...

Yep, I used one to try and tune my B. When the colortune said it was correct, I found I was running WAAAY too rich. I would save your money and spend it at a dyno instead. I was dissappointed.
 
I've used one and thought it was good. It's not the greatest tool, but it does help to confirm your adjustments and condition of your carbs. They're nice to have, but I wouldn't go without food to get one.
 
I've been pondering a Gunson Gastester, instead. More $ (about 150-200) but I'd really like accurate readings of A/F ratio for carb adjustment.
 
On my next project, I'm dying to install a 5 wire exhaust gas sensor. A friend installed on his MKIII GT6, with a gauge in the tunnel console. You drill a hole in the exhaust header, weld the sensor in, wire it up, install the gauge, and you're then just like Special Tuning Abingdon (well, almost). :crazyeyes:

It is a tremendous help in fine tuning the engine. His GT6 had twin SUs, and got the engine running perfectly with opimal fuel economy, power, etc.

I'm gonna get one on my next LBC.

Anyone here have such a setup? What's it like???
 
well Duncan you can borrow my colourtune to start with if you wnat to give it a try.
 
Barry, the colourtune is just a spark plug with a viewing window, so you can see the flame go from yellow to blue and get the stoichiometric (sp?) ratio close. The Gunson Gastester is a 'sniffer' that goes in the tailpipe, and gives you exhaust gas readings. You'd be able to check your ratio at idle, cruise, heavy load... should allow you to get much closer.

Greg, I'll definitely take you up on that, I'm interested to see whether I've now got it about right!
 
On my B, I welded in a O2 sensor bung the last time I had the exhaust off the car. They are cheap and you can pick them up at most parts stores. I haven't yet had the time to play with it on a Dyno or buy a gauge.
 

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John Moore said:
On my B, I welded in a O2 sensor bung the last time I had the exhaust off the car. They are cheap and you can pick them up at most parts stores. I haven't yet had the time to play with it on a Dyno or buy a gauge.
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Yes, I'd definitely consider that... but I really don't want to pull the header off during the driving season, if I can avoid it. Might go on the winter to-do list...
 
I've thought about the gas tester, but I had one concern. I seems to me that you have one sensor, but two carbs, so you could easily get one carb rich, the other lean, and the combination would seem OK to the tester. Is there some way around that problem? Or is it more theoretical than real?

Inquiring minds want to know...
 
You can certainly install two bungs, and take readings off two o2 sensors, if your manifold / headers permit. But with a tailpipe sensor, I suppose you would have to assume that if your carbs are set equally, they should both perform similarly.

I suppose a more sensitive (five-gas) tester could pick up other readings (unburnt fuel, CO, etc.) that would let you know if one or the other was running rich or lean.
 
Yes, I think that's the only solution. I don't relish the thought of drilling two holes in the exhaust header, but I suppose it could be done. Probably requires carbide tools. The more I think about it, lifting carb pistons seems just fine....
 
I have just ordered an Auto Meter gauge for my car.

If you are going to go this route definately get a wideband and they are some $$$

My concern is hooking it up on a positive grnd or having to convert it to negative.
 
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