Colourtune

[Burdekin]

Anyone used one? Just rebuilt my carb so need to set the mixture and using a colourtune. It’s not clear cut or as bright as I would expect. Does it need to be reasonably dark for them to be clear? I’m colourblind so am having a few issues trying to see the colours, maybe would be better if it was dark? I used a wideband sensor previously but don’t have a bung welded in the exhaust on this car. Any other good tuning tools that are used for setting mixture?

 

[zzr1200]

Shield the colour tune glass with a toilet roll tube and look straight down the centre line.

The best tools I have are my ears for tuning engines....

 

[JMS1972]

It's been a while since I used one, but stay out of bright sunlight?

 

[zzr1200]

It's been a while since I used one, but stay out of bright sunlight?

Or do it at night.....

 

[Cato]

Vacuum gage/s will give you accurate results.

 

[KemppiFrog]

Blimey, bought one in the 60s and used it a bit. Might have helped with the mixture somewhat? But so,so. Gave it away in the 80s. Do they still sell them? The idea is right on, but one needed to use them on the move, rather than static. I do remember being perched on the engine driving up a steep hill while fettling a Fish carb on a friend's Mini. Always slightly afraid of it popping and causing personal damage.

 

[daedalusminos]

The colourtune used to be supplied with a light excluding tube with a rotating mirror on top - made it much easier to view in bright sunlight

 

[graffian]

The colourtune used to be supplied with a light excluding tube with a rotating mirror on top - made it much easier to view in bright sunlight

They still want to be used in the dark.
As someone else said ears are pretty good tools.

If you think colour tune is hard to use, you want to try timing a Harley with a clear timing plug.

 

[Burdekin]

Vacuum gage/s will give you accurate results.

How do you do it and how does it work?

 

[mtt.tr]

i just do it by ear

 

[optima21]

tried a colortune years ago for my polo's for idle mixture and the colour didnt seem to change much, these days I do it with a vacuum gauge.

to do it with a vacuum gauge I adjust the idle mixture so that you get the maximum vacuum for a given rpm. the simple theory is that the better the combustion, the more power you will produce, the more power you produce creates the biggest vacuum in the inlet ports .

I use a gunsons lo gauge like this

you're looking for 15 to 20 inches of mercury vaccum at idle so a cheaper option may be to use one of these

Pardon our interruption...

and just make an adaptor.

you should be able to use the vacuum connection to the distributor to plumb it into when testing

if you're interested in old school tuning, the book "the sports car engine" by Colin Campbell is a good read.

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prices do vary though

 

[Nomad]

I've had one for years and it's a useful tool.

Either do it at dusk or in the garage where it's shaded (I always find it difficult to see when I'm outside in daylight).
It works great on some carbs, others bounce around between rich & lean (I guess due to worn carb internals).
I always check ignition timing first on older engines before using carbtune, timing at tickover often jumps around which makes setting the carb "by the book" almost impossible.

A vacuum gauge is another option.

Good luck

 

[Cobbler]

I’ve got one in the shed, I used to use it for doing the mixture on twin SU’s, it was very good for that as you can see the carburettors individually. A small point about fitting a vacuum gauge, on some engines you can’t use the distributor vacuum take off as it is into the butterfly venturi in the carburettor & doesn’t read manifold depression

 

[waddycall]

What about reading the plug?

 

[tom2207]

just do a cut test and look at the plug ,, I didnt think colour tunes still existed anymore.

 

[8ob]

What carb or car are we referring to here

Bob

 

[500e]

Fish carb on a friend's Mini. Rees fish theirs a blast from the past good idea never in tune for long

 

[Burdekin]

What carb or car are we referring to here

Bob

Stromberg 175 on a Volvo B20

 

[minimutly]

The yank bikers on the Yam xj forum swear by them. I binned mine.

 

[colnerov]

Hi, The trouble with them nowadays is that modern fuels burn differently and flame colour is not so noticeable or as clear cut. So they're not suitable now.

Colin