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' Light your lamps at 6.50 in London, 7.36 in Edinburgh, 6.59 in Newcastle, 7.3 in Liverpool, 6.58 in Birmingham, 7.0 in Bristol, and 7.45 in Dublin.
The sender of the following communicationhas been. awarded the 112s., prize this week.
 " J.E.J." (Wandsworth) writes :—" My experiences of Petrofin, which I used for some months in a 40 h.p. Leyland may be of some use to other readers.
"As soon as the petrol shortage commenced to be felt, I removed the Claudel-flobson carburetter and fitted a Solex. I disconnected the hot-water supply to the water jacket on the inlet pipe., and substituted instead exhaust-gas heating. A supplementary tank for petrol was fitted on the dash, the existing reservoir being used for the substitute. Independent taps control the supplies from both tanks. "The engine is started on petrol ; after a time, when everything has warmed up, the Petrofin is turned on, and supplied neat. When about to stop the engine, I turn off the Petrofin, so as to empty the float chamber, and leave room for petrol for starting purposes.
"I find I get 7 m.p.g. from this substitute, running from 50 to 60 miles a day. I use about gallon of petrol a day for starting and warming up. I have had no trouble with plugs, or thinning of lubricating oil. As an improvement I should like to have a thin induction pipe, of copper, surrounded by another, of large bore, as a jacket. The present one takes too long to heat."
The Rejuvenation of Sparking Plugs Which Have been Damaged by Paraffin Fuel.
1725] "RR." (Stocktc.n-on-Tees) writes :—" After using various mixtures of petrol and petrol substitutes for over nine months, I have found that one of the minor drawbacks to the use of a mixture containing more than 33 per cent. of substitute is the wastage of sparking plugs. They are prone to fail by internal shorting, and I believe the trouble is due to the searching propensities of paraffin when it is in a partially-vaporized state. "The. paraffin (which is the basis of most of the substitutes on the market) is blown up between the insulator and the shell of the plug, and also between the central electrode and the insulator, and forms an oily soot, thus causing a short circuit, and no amount of washing with petrol will make the phig fire for more than a few minutes.
"The resultant scrapping of sparking plugs where several ears are kept in constant use is expensive, and in my case I soon had a collection of a dozen or so of different makes of plugs all suffering from the same defect. Most of them, unfortunately, were of the
Lodge or Bosch type, with fixed insulators, which are no intended to be taken apart for repair. I was determined to remedy the evil, however, and set to work to find a way to make these plugs as good as new. Eventually I hit upon the following method, which I will describe for the benefit of your readers ; it will save them many pounds, as the same remedy will cure • any plug which has been over-oiled or is carborted up. Personally, 1 never have need to scrap any plugs unless the porcelains are cracked. " Itake half-a-dozen plugs. and lay them on a piece of sheet iron amongst the cinders of my brazing hearth, placing the plugs in the form of a star, with all the screwed ends pointing to the centre. I then play the blowpipe flame on the metal portions, applying a uniform heat to all parts. Very soon vapour will commence to pass out of the end of the plug and will ignite. When the emission of vapour ceases, all oil deposit has been burned up and the plug will nowbe at a dull red heat. The gas should be shut off, and the plugs covered over with large cinders and allowed to cool down gradually. Care must be taken not to raise the beat too quickly or to overheat the plugs, such treatment may result in cracked insulators or in breakage of the joint between insulator and shell owing to unequal expansion. After the plugs have cooled, they may be uncovered and removed. It will then be found that inside is a quantity of carbon in the form of a brittle scale. This may easily be loosened with the aid of a small probe or scraper ; the • latter may be made from a piece of flattened piano wire. If the probe is made properly, all.the interior of the plugs can be reached. After a good blow out with an .air-biaste(a foot pump will do admirably), the plugs will be found -to be as good as new, and to have received a new lease of life.
"No doubt some of your readers will think this rather drastic treatment, but if carefully done, no harm can be caused, as it must not be forgotten that in actual use the inside of the plug is generally maintained at a red heat whilst the engine, is running. I have been treating plugs in this way for months now, and have been agreeably surprised at the results ; since adopting this method I have reduced my plug bill fully 50 per cent."
How to Repair a Top Gear Clutch which Persistently Slips Out. [17261 "HA." (York) writes :—" ()xi chassis that have seen years of service, a difficulty is frequently experienced in engaging the tee) gear, due to the fact that both members of the clutch have worn their (originally) straight faces off at an angle which under the drive, causes them to separate in a longitudinal direction. A makeshift remeely is to grind these tooth faces straight or, better, under to an angle of 3 degrees or 4 degrees. The engaging parts then have a tendency to draw in and will .stay in place."