Using colour for tell-tale tuning
Page 34
If you've noticed an error in this article please click here to report it so we can fix it.
CM puts the Colortune 500 kit through its paces
THE operator with one or two petrol engined vehicles doesn't necessarily want to spend a .lot of money on complicated electronic diagnostic equipment to keep them in good running order.
The trouble is, a poorly tuned engine can add substantially to fuel bills by wasting petrol, and in some cases the life of the engine can be shortened. Dilution of the oil by excessive petrol washing the bores is another potential problem.
Regular servicing can of course keep an engine up to scratch, but often the carburetter is neglected or incorrectly set giving poor performance and irregular running.
To help with correct carburreter setting, Gunsons of 66 Royal Mint Street, London, offers the Colortune 500 kit and CM has recently been putting it through its paces.
The Colortune kit consists of four units which are screwed into the warmed up engine in place of the existing sparking plugs. In the case of a six-cylinder it's advisable to fit the Colorplugs in each end cylinder and the two centre cylinders.
Four plastic viewing tubes are attached to the Colorplugs by means of insulated asbestos/tufnal lower sections and extension plugs leads are fitted, with the vehicle's ht heads being plugged on.
Once the engine is started the revs are set at about 800. By looking down the viewing tube (or into a small hinged mirror on the top) the colour of the combustion in that cylinder can be seen.
The principle of the Colorplug is that excessive fuel burning will give an orange coloured flame indicating a lack of oxygen, while a weak mixture. shows up as a white/blue colour. By adjusting the mixture until it turns through orange to a clear blue the correct setting is obtained.
We tried the Colortune on a variety of vehicles including one fitted with twin carburetters. In every case, by following the instructions carefully we obtained very good results. One vehicle, fitted with an SU carburetter, responded so well to the device that fuel consumption rose substantially, even though it appeared to be running correctly before receiving any attention.
The Colortune outfit can also be used to check and adjust static timing by using it as a timing light and setting the distributor up on one cylinder. Although we found the Colortune did all its maker claims, we were a little concerned as to the durability of the kit's component parts. In fact the plastic viewing tubes look quite fragile and one wonders how long they would last in garage workshops.
Colorplugs themselves look fairly robust except for the porcelain centre sections which could suffer if dropped when being removed.
Nevertheless, for the do-ityourselfer who is likely to take more care of the outfit, the Colortune kit represents good value at t.:29.50 excluding VAT.