Baconsdozen Imperial Tools.

Sorry,all colortunes and adaptors now sold,we have left this page as it contains instructions for use of the colourtunes at the foot of the page.

Gunson Colortune.Set carburettors,increase power,reduce emissions and save fuel with better m.p.g .

For variable jet carburettors like SU or Stromberg or where the needle can be adjusted (for example older Amal carbs),the Gunson colortune is an ideal tool to check and adjust the fuel /air ratio. For all carburettors and injecytion systems colortunes (should that really be colourtunes?) can  diagnose rich or weak mixture and help in jet selection and adjustments to fuel/mixture ratio. The newer Colortunes can be used at light throttle openings and idling to check the fuel/air ratio throughout the engines rev range.The standard colortune fits the common 14mm spark plug holes a 18mm adaptor is used to fit the colortune in many classic cars and older fords etc that use the 18mm spark plug holes and for smaller engines 10 and 12mm adaptors are available. We can accept card payments by phone on (44)01493600718.


Gunson 14mm colortune kit.Ideal for older cars and bikes with variable main jets (SU Stromberg etc) or where the needle can be raised or lowered (Amal carburettor etc) and can check the fuel/air ratio on all petrol engines Simple to use,the colortune simply replaces one of the spark plugs to test and check and the removed plug replaces it after use..

.Larger picture click here

Gunson 14mm colortune

Adaptors available seperately contact us for post prices etc...

Colortune 18mm adaptor.Enables the standard 14mm colortune to be used in some early Ford cars or American vehicles that have a 18mm threaded spark plug.Allen key (supplied) is used to tighten the adaptor and the colortune screws into it.5..50

Colortune 18mm to 14mm adaptor

10 adaptor for the 14mm gunson colortune.Allows the colortune plug to be used in engines that use a smaller spark plug hole (motorbikes,quad bikes,mopeds,generators and chain saws etc).Screws into cylinder head with a spanner,the colortune is then screwed into the adaptor.Price 5..00p

Colortune 10 and 12mm adaptors

 12mm adaptor for colortune.Similar to the above adaptor Enables a standard 14mm colortune spark plug to fit 12mm spark plug hole.5..00

Click here for larger image.

The Colortune adaptors listed above (10mm,12mm and 18mm ) can also be used to fit 14mm screw in type compression testers etc to different sized spark plug holes..

The Gunson colortune and how it works.

The Colortune is a glass topped spark plug which simply replaces one of the vehicles normal spark plugs the glass top lets the operator look into the engine cylinders and observe the combustion flame colour.The colour of the flame gives a reasonably accurate of the fuel/air ratio in the same way that the colour of a bunsen burners flame colour alters with the gas'air ratio. Varying the mixture strength changes the flames colour and the carburettor can be adjusted to reduce emissions and waste,optimise fuel economy and increase power .The Gunson colourtune kits we supply come with full instructions (see bottom of page) ,an extension for the HT lead and viewing tube with mirror.

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Whitworth,BSF and BA sockets and spanners 

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Gunson Colortunes,Instructions for use.

Instructions are enclosed with colortune kits we supply. They used to be in colour but are now in black and white .

With the engine at running temperature a spark plug is replaced with the colortune.With the engine ticking over the colour of the combustion flame can be observed through the glass top of the colortune.A white or pale blue flash indicates a weak mixture and an orange or yellow colour indicates excess fuel.The mixture screw should be adjusted to obtain a bunsen blue colour.The mixture can be checked at higher rpm and blipping the throttle pedal quickly should show a momentary enrichment for acceleration before settling back to blue.If the mixture is too weak and can't be corrected with adjustment suspect a vacuum leak or blocked jet(s) a vacuum gauge can help trace any leak.Trickling Redex or a thin oil around suspect gaskets can reveal a leak as the oil is drawn in and blue smoke comes out of the exhaust.A rich mixture especially at higher revs might be a partially blocked or oil soaked air cleaner,too high float level or a leaking float valve.
Before adjusting the mixture the ignition timing should be checked and adjusted if necessary with a strobe light,valve clearances and spark plugs should be checked and the air filter cleaned or replaced if necessary.

We do not consider a Colortune will give a correct reading on methanol or other fuels. Heavy oil burning,excessive two stroke oils or the use of too much of some additives may effect the combustion flame colour.The glass top of a colortune is quite robust but can be cracked or damaged by dropping the unit or running at maximum revs.The glass will get hot so take care in handling and removing.As with any tuning aid if there are defects with the engine (timing incorrect,valves badly adjusted or air filter choked etc) the colortune will not work correctly.

Baconsdozen tools for older cars.

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Tel (44) 01472353993