(Jdm honda parts) The Performance of Antique Car Engines
No commentsBy Peter Salmonford
It is often assumed that when an engine is new it gives its maximum power, but in actuality this is not the case. At the outset the bearings are tight and the bearing surfaces comparatively rough, and it is not until the engine has run some months that the highest power is developed. It is not to be assumed that up to this period the engine gradually increases in power, but that a higher power can be obtained from an engine after being well run in than when it is new.
In actual practice the engine gradually gives less and less power unless it receives the necessary small amount of attention to keep it up to its best pitch. The cause of this is a gradual loss of compression, chiefly owing to the burning away or pitting of the valves and their seats, the remedy for which is regrinding. Valve-grinding is a somewhat laborious process, but it is one which generally effects considerable improvement in the engine’s running, and it should be made a periodic practice, and not be left till the engine is running very badly, as the necessary grinding will then be somewhat difficult.
If a valve is examined it will be found that it has a flat angular surface on the underside of the head, and this surface rests upon a similar conical surface, called the valve seat, formed in the cylinder head. These two surfaces must be absolutely true and smooth so as to prevent any gas leakages when the valve is closed by the valve spring.
When the exhaust valve is opened the exhaust gas, which is an intensely hot flame, passes between these two conical surfaces, making them practically red hot, which is their normal condition during running of the engine. It is hardly surprising, therefore, that in course of time the surfaces deteriorate, and the necessity for regrinding can be ascertained from an inspection of the valve and its seat. If smooth and bright all round, the valve is in good order. If dirty and rough, it requires regrinding. When loss of power is experienced, to ascertain if it is due to loss of compression, the engine should be turned round slowly, with the switch off, and if the resistance on the compression stroke is not what it was when the engine was new, it is clear that there is a leakage somewhere, and the exhaust valve should then be examined as mentioned. Possibly only one or two of the valves are at fault, so the compression in each cylinder in turn should be tested in this way.
Before a valve is ground in it is, of course, necessary to remove it, and this, with its replacement, forms probably the most difficult part of valve grinding, on account of the stiffness of the valve spring, coupled with the fact that the parts are generally difficult of access, on account of the presence of the piping, etc.
Peter Salmonford is a keen fan of cars, and likes to write about antique and modern vehcles. Take a look at his other articles on hydrogen conversion, the benefits of an electric car kit and using browns gas in your own car.
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Handling Soot in Antique Car Engines
By Peter Salmonford
In the course of running soot is formed in the engine, the quantity varying with the richness of the mixture and the facility for the lubricating oil to get past the piston. This carbonaceous deposit, combined with the non-inflammable constituents of road dust which are sucked through the carburetter, adheres to the cylinder walls and combustion head, causing falling off of power, and in time preignition. When the valve cap is removed it will be found that its underside is coated with soot, and sometimes even with a hard deposit, an indication of the state of the interior of the cylinder. To remove this carbon deposit, the usual procedure is to take off the cylinder so as to expose the parts and scratch off the deposit with a screwdriver or some similar instrument. From the tops of the piston the deposit can be cut away with a knife, and when removed the surfaces should be polished with fine emery cloth, as deposit adheres less easily to a polished surface. The deposit must be completely removed from all parts of the cylinder as well as the piston, a matter of some difficulty.
There have been one or two inventions evolved from time to time to remove the deposit without necessitating the dismantling of the engine. One of these is to insert a steel ball of about 5 inch diameter into the cylinder and then to run the engine, its action being to hammer the carbon deposit and so chip it off the surface. Another, and more promising, process consists in passing a stream of oxygen into the cylinder, lighting it, and so causing a chemical combination to take place between the carbon and the oxygen. As soon as all the carbon has combined the flame goes out, and it is known that the cylinder is clean. The writer has not tried either of these schemes, but mentions them as matters of interest. The ball process, however, would seem rather risky.
To keep an engine in good running order the valves, apart from grinding-in, require careful attention. In the olden days silence of running was not of great importance, but nowadays it is an essential, and to obtain it one of the most important points is to see that the clearance between the valve tappet and the bottom of the valve stem is small. As the engine runs it will be understood that the tappet rises rapidly and strikes the foot of the valve. If there is a large clearance between these two the impact between the tappet and the valve causes a clicking noise, which should be stopped by adjusting the tappet head close up to the valve stem. The usual distance or clearance is about 5 inches. The top of the tappet head is inlaid with fibre to reduce the noise, and in course of time this fibre becomes dented or recessed. The tappet should then be removed and its head filed flush so as to remove the indentation.
Peter Salmonford is a keen fan of cars, and likes to write about antique and modern vehcles. Take a look at his other articles on hydrogen conversion, the benefits of an electric car kit and using browns gas in your own car.
Monday, September 29th, 2008 at 11:35 am and is filed under automotive. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
