Gunsons Colortune

[Iansparky]

Hi
Has anybody had any experience of using the gunsons colortune for setting mixture on the SU carbs, at 1st glance it seems an easy way to get the mixture spot on, however some reviews of the product say that it doesn't work very well with modern fuels.
Thanks
Ian

[chrisfell]

I have, several times on different cars over a +40 year period. Never worked for me.

Search for SU tuning on Jag-Lovers.

[abowie]

I've had the same experience as Chris.

Whether it was because I didn't know what I was doing or not I didn't find it helpful to tune my cars.

I do have a Gunson 4125 CO meter. This is an excellent aid to tuning, especially with triple carb setups.

[malcolm]

I used the colortune on my 2+2
I set it up exactly as told in the instructions, and it ran terribly. Mainly I think because the E likes to run richer than other engines so if you set it to all blue flames it's too lean.
I did it again, but set it up so each cylinder was showing some (and the same amount) of yellow flame on tickover, and it worked quite well.
Since then, I've ignored the Gunson, and just adjust incremental amounts until it runs right!

[caveman]

Like Andrew, I have had great success with Gunsons CO meter and triple SU. Colourtune

[Iansparky]

Do you insert the probes from the CO meter in the tailpipes or have you had bungs welded in the manifold

[caveman]

Tailpipes. Takes a bit of getting used to adjusting the centre carb across 2 exhausts but straight forward enough.

[Rich70]

I use colourtune, successfully, on my Westfield kit car which has a Weber DCOE 45 setup. My S2 also has a new DCOE setup but I am yet to use colourtune on it as the engine has been freshly rebuilt and is out of the car.
When tuning my friends MG with SUs I use two colourtune plugs as the carb feeds two cylinders and I find you get better view of the shared fuel burn this way.
CO2 or wideband lambda monitoring is great but when measuring a combined cylinder output be careful that you don’t have one cylinder running lean and one rich.