Show k AND P J 1 1 c A OUT A A ILES EXPERT GIVES DIVES INSTRUCTIONS ON METHOD OF TIMING AN AUTOMOBILE ENGINE Ifan has been taken down R U. U n engine t tho o timing l gears must be replaced In cb a manner y that the spark will at atthe the top of the compression compression- trek oke with both exhaust and inlet 1 toy yes v closed If It there are marks on tV iha r teeth of the gears this is not a aa n a a l lt thing to do and fortunately x 6 t engines are so made But Dut ocr oc- oc Jl r r f.- Uy one comes across an nn engine r ri as as' s' s been dissembled for repairs o iS r ov overhauling in which the timing t i r have lia no Identification marks to their setting In such a case caser r w fo three things to to- todo do ace accord accord- rd- rd v to to B B. B M M. Ikert in Motor Age Taking the of ot four four- i case a typical f J k engine using a high tension r 1 r magneto for example First the piss J. J t i n of or No 10 1 cylinder is brought to 4 fM o toP the valves placed In the corI correlation cor- cor I ct r relation to it It and finally the thet t 1 agneto eto breaker points and t tor arm arranged so that the spark wi will occur at the proper time In f 1 most cases cylinder No 1 that I-that that nearest nearA near- near A j est cst the radiator radiator radiator-Is is the one that is k timed and if It this Is done correctly t nil all of ot the tho other cylinders will be timed r likewise because the cams on the thea a c camshaft Cf aft are integral with it and correct correct cor- cor feet timing of or all cylinders automatically r j C rally cally lly follows the first S The diagram herewith shows the re re- re r of the tho principal parts such as asi i tha tho valves piston magneto points etc b Of a four cylinder engine when it is isi 4 i at the of ot firing The firing order of this engine is 4 3 but this can l s 1 bo be 0 4 3 In which case there t 0 will be a a. different arrangement of I the tho wires leading from the magneto distributor to the plugs Tho The smaller netted dotted circle shows the gear attached tt the crankshaft which meshes with the iho camshaft gear shown by the tho larg- larg circle The arrows show the direction in which tho the parts revolve The Tho arrow on the outside of the r 1 magneto breaker points housing shows t the e direction In which the armature revolves In retarding the spark the lover lever on tho the housing Is swung in tho the 1 game samo e direction Although both intake exhaust valves for this cylinder be be e closed only one can be bo shown this is the intake valve Note On t tho the cam earn has turned so that the Valve is completely closed with a slight space between the end of ot the valve stem and tappet or push rod the lowr lower low- low er r 1 end of which rests on the cam earn gyp o take a specific instance let us r ji e ume that the engine Is 1 ed q with the tho exception of the timing J r oars oars and magneto drive The latter jt t be In the form torm of a chain or I pra like those that drive the cam cam- rl n The first thing to do is to place he piston of or cylinder No Ko 1 at the top j dead center point If It the engine Ish is isi h F i fitted with spark plugs in the center of the tho combustion chamber a wire can tie be inserted in the hole and by slowly turning the engine over the wiro wire will rise riso with the tho piston and when it ceases to rise obviously the piston Isas is isas isas as high up in the cylinder as it can go c A al better way would be to remove the plate on the bottom of the crankcase and note the position of or the crank- crank shaft hatt When the cranks are aro in a perfect perfect per per- vertical line so that No Ko 1 is up the ahe piston will be in the top at dead center If It tho the engine Is of ot the L-head L type with tho the plugs and p pet t cocks over the the valves it will be more difficult to find the tho top position of the piston but a small electric light can be brought close to the spark pl plug g hole and the light will wm show the piston piton as asIt asit asit It begins to come coma near the top By carefully turning the engine and watching the piston it can be correctly correctly correctly cor cor- placed With the valve in engines if it the valves are held in cages the latter can be bo taken out and the piston watched through the opening With the piston of No 1 cylinder inthe in tho the correct position that Is as far up as It will go the next step Is to to j get the valve placed correctly for It In Inthe Inthe Inthe the the- first place the tho piston is supposed to be at the top compression center and In order that the gas might be compressed the tho valves will have to be closed Before tackling the tho valves make a a. prick punch mark on the flywheel flywheel fly fly- wheel rim at the tho extreme top Make a a. similar mark on the engine crankcase crankcase crankcase crank- crank case opposite the one on the flywheel co so that both marks will be coincident I with a line drawn vertically through the tho center of the flywheel These marks maries are made so that that-if It the engine I has to be later on n. n the flywheel fly fly- i wheel l can be revolved so the marks register resister and the operator will wm khow I that the piston of No 1 1 as w well as i I r i f m 1 ON P. P TER 0 L I ARM MM ON ON 1 CYLINDER LINDER SEGMENT SEG SEG- MENT F k- k j i INTAKES INTAKE b EXHAUST LV 5 Ill 4 rO I jm o 0 I t I J I 1 r RETARD FULL 1 POINTS TO OP OPEN Nr f 1 4 wr t t T non I O N or OF f. f L.- L. t u J 4 r 1 0 J 1 J. J jr Diagram showing how a four four cylinder cylinder with high tension magneto is timed Piston No 1 cylinder on top topp top compression center both valves closed spark fully breaker points just about to open and distributor arm on segment for No 1 cylinder v a that for tor No Ko 4 is at the top of the stroke The figures 1 and 4 should be stamped near th the marks marls to show what pistons are on top A mark made at a point diametrically diametrical diametrical- ly opposite the first on the flywheel would show that pistons 2 and 3 are areat areat areat at the top when it registers with the punch mark that is on the engine base To get the time tune of opening and closing closIng closing clos clos- ing of the valves rotate the camshaft in Its normal direction and watch the movement of the valves in cylinder No 1 1 There will be a time when both valves are closed and further rotation of the camshaft will cause the exhaust valve to open The latter does not happen immediately however for the piston will be on the power or firing stroke and the valves must be kept closed until near the end of this stroke when the exhaust begins to open to let out the burned gases Turn the camshaft back to where the exhaust and inlet closes completely with the cam for the latter in the position shown in the diagram VALVES TIMED CORRECTLY Now slip the camshaft gear which gear which is twice the tho size of ot that of the crankshaft crank crank- shaft shaft back back on the camshaft so that the teeth mesh with the one on the crankshaft If there is a different form of drive for tor the timing gears ears such as asa asa asa I a chain it should be connected with the piston and valves in the position above After this is s done the engine will wul be timed correctly in regard to the valves and the timing of ot the ignition ignition ignition igni igni- tion can be taken up The first thing to do is to put the magneto in the correct position that is revolve the armature shaft shat by hand until the breaker points are about to separate This separation takes place when the fiber block on the end of the bell beIl crank comes in contact with one of the cams on the insl inside of ot the contact brealer breaker box These cams are shown in the diagram by the shaded portion Remove the cover from the distributor housing and note the position position position tion of ot the distributor arm If It it is near or on segment No Ko 1 it Is in the correct position otherwise the armature armature armature arma arma- ture shaft will have to be rotated again until these conditions are arc realized Make sure that the arm or lover on the interrupter housing is in the extreme retarded position This can I be done if the magneto has not been removed from the engine base by placing the spark lever on the steering steering steer steer- in ing wheel l In the retarded position steer steer-I Keep the magneto In this position and slip the gears in place so that all mesh properly In other words have the magneto armature and distributor correspond correspond correspond cor cor- respond with those that are shown In Inthe Inthe inthe the diagram TO FIRE PROPERLY When the mechanism of ot the engine and magneto is brought together so that the parts bear the relation as illustrated and when the gears put back the engine will wUl fire properly Sometimes setting the g gears ars one tooth either way after atter timing will result in better running |