Show IS IT CYLINDER OR PISTON RING when engine lacks power and compression Is poor make examination by ERWIN REER GREER G president greer college of automotive engineering chicago there Is nothing mysterious about piston rings used in automobile engines even though repairmen will tell you that new rings bt bf a certain sort will elevate your engine into some new state in which it produces twice as much power and speed as before there Is a good deal ot of misinformation about piston rings and because ot of it automobile owners spend millions each year for such parts in many cases getting no results from the expenditure pend iture piston rings are supposed to pack the cylinder so that the gas does not leak downward and oil upward in order to be an ideal device it must do this without exerting too much pressure against the cylinder wall and the pressure must be evenly disario distributed all around the ring must fit tile the cylinder perfectly it must fit its grooves in the piston so that it will iiii be neither too tight nor too loose find cause of trouble such piston rings will run perhaps or miles but a time tim e must come when the rings no longer make a gas tight joint it then Is n necessary ec essary to find out why the rings no longer fit well the average aver ae repair man will toll tell you that when wear takes place only the rings become worn so that all that Is necessary to put the engine in first class shape Is to replace he ake piston rings now how the repair man knows Is one of tile the mysteries of this world the fact Is that no one can tell whether the rings are worn or whether the cylinders are worn or just what the condition of these parts Is unless the parts themselves are examined and measured this explains a great deal of trouble owners have because so called oversize rings were installed in the cylinders in the first place the cylinders should be made true either by grinding or some other process and new rings obtained to fit the new bore in this way only can one be sure of a perfect fit to say that new rings will lap themselves into an bore Is wrong for they them will not nor will new rings ring s in worn cylinders t take aloe the shape presented by sare marks or hard bard spots in the cylinder metal met al rings do not fit when your engine lacks power when the compression is poor hben it pumps oil and uses too much fuel it usually Is a sign that the aln rings s do not fit properly but it Is not a sign that new rings alone will cure these troubles you must find out the condition of the cylinders into which the rings fit this means tile the grooves must be trued in a lathe to the exact size of the new ring |