9) When the fuel mixture is not properly pro portioned, try making a lean mixture, that is, cut down the amount of fuel for the quantity of air wed.
Where a carburetor is employed to provide the fuel mixture if the latter is too rich at high speeds and when the load is light the cylinders will heat up unduly. To remedy this defect all you have to do is to cut down the amount of fuel or to adjust the butterfly valve in the main air inlet, or auxiliary air valve, until the fuel mixture is of the right quality.
(10) If the valves do not seat properly they must be ground, as I explained in paragraph 9 under the heading of When the Engine Works Badly. (11) An engine may overheat if it is new and has not been run in, but this should, of course, be done at the fac tory, and not at your expense. When you get such an engine, all you can do is to run it at a low rate of speed until it is tuned up.
(12) Finally, if the radiator is too small to keep down the temperature of the water which circulates through it and the water spaces around the cylin der, the only remedy is to get a larger radiator and put it on.
First Aid to An Injured are a lot of little things that get the matter with internal combustion engines, and if you let them go they may develop into real troubles, and this is particu larly true of small units.
Stretching Valve you find that your engine does not run as smoothly as you think it ought to, put the blade of a screw driver between the turns of the valve spring, as shown at C in Fig. 69. If this makes the engine run steadier or it picks up in power it shows that the spring needs stretching, so take it out and stretch it or, better, put in a new one.
Leaks and How to Stop leak in a gaso line or an oil pipe if it is not too large can be stopped by putting a piece of common brown soap in the hole and then wrapping the pipe with a piece of electrician's tape or adhesive plaster tape. This is a first-aid repair and, of course, you must solder the leak as soon as you can.
If the water leaks at the joint where the flanges of the water pump and pipe are bolted together you can stop it temporarily by driving a thin, soft pine sliver into it, and this will last until you can put in a new gasket If your engine is a mobile one and has a radiator on it you can stop a leak in it by plugging up the hole with a bit of chewing gum.
To stop a leak around a spark-plug either screw the plug in tighter, or if this does not do the trick put in a new one.
How to Clean Spark-plugs.—Dip an old tooth brush into some gasoline and scour off the points of the plug with it. If the deposit of carbon on them does not come off you will have to scrape it off with the blade of a knife or use a jeweler's file. When you have the points nice and bright wash them off with gasoline.
Cutting New Gaskets.—When making new gas kets use asbestos packing with a brass wire mesh' in it, for rubber packing will often rot or burn out when subjected to hot water and hot gases.
On Making Small if you are not mechanically inclined, when some small part breaks on your engine you can get a repair part from the maker and replace it yourself. By so doing you will not only save money, but you will get a better work ing knowledge of your engine, and this is decidedly the right thing to do.
Every maker of good engines issues a price-list of parts, and as these are interchangeable you can send and get a replacement for any part of your engine, from the smallest screw on up to the base, and you can be morally certain that it will fit ex actly when you get it.
About Making Big isn't very often that anything goes wrong or breaks on a big engine, but if some part should, you can get a duplicate of it just the same. It may just be that you feel you are not competent to make the replacement, and if this is the case get a machinist at any shop and he will do it for you at a small cost.
Where a large part is broken, such as a connect ing rod or a crankshaft, or a cylinder is cracked, you can have the parts welded together cheaper than you can buy the replacement.
Welding is done by three different processes, and these are (1) the oxyacetylene, (2) the electric and (3) the thernvit processes. By writing to the fol lowing companies you can find the nearest shop to you which has one of their equipments and where the part can be welded. The Prest-O-Lite Co., 206 Am sterdam Ave. ; Thompson, Electric Welding Co., 30 East 42d St., and Golclschnvklt Thermit Co., 120 Broadway, all of New York City.