Locating TDC (Ton Dead Center) for Distributor Installation when tnstalltng the dtstrtbutor, the rotor must potnt to the proper locatton on the cap to ftre correctly There are 2 crankshaft rotattons (And 2 TDCs) for every 1 rotatton ofthe dtstrtbutor and camshaft The crankshaft TDc ttmtng marks ltne up when the dtstrtbutor rotor ts at both the correct locatton and when tt ts 180 degees off One method of locattng the rtght TDc ts to remove the #l spark plug, put your thumb over the hole (Dont put your ftnger tn the hole, the ptston could htt your ftnger), rotate the engtne or feel for atr pushtng out to locate the compresston stroke, then ltne up the crankshaft mark on TDc for #1 If a valve cover ts off you can use the followtng sure ftre method In engtnes wtth an even number of cyltnders the ptstons are patred and travel up or down at the same ttme, but are on oppostte strokes In the ftrtng order these patred ptstons are oppostte ofeach other You can locate TDc tn #1 by ftndtng valve overlap tn the cyltnder oppostte of #l tn the ftnng order If the ftnng order ts 17574727637778 then #6 ts the oppostte of #l 548 then #6 ts the oppostte of #1 (Again) 24 then #6 ts the oppostte of#l (Hmm, seems to be a pattern here) If the ftnng order ts 17 If the ftnng order ts 17 Cylinder #1 Arlnmke stroke arts at TDC wtth rotor pumtmg oppostte #l rlntake open Exhaust elosed rFlstun travels down rCyllnder lls wtth Atr/fuel mtx B Cnmgressmn Stmkz rlntake elosed Exhaust elosed rFlstun travels up rAJr/fuel mtx ts compressed Canwer Stmkz Starts at TDC wtth rotor pmntmg at #1 rlntake elosed Exhaust closed Spark plug ftres rAJr/fuel mtx explodes rFlstun ts pushed down DrExhaust Stmkz rlntake elosed Exhaust open rFlstun travels up Exhaust ts expelled At the same time in the Cy lnder opposite #1 Aanwer Stmkz Starts at TDC wtth rotor pmntmg oppostte #1 rlntake elosed Exhaust closed Spark plug ftres rAJr/fuel mtx explodes rFlstun ts pushed down BrExhaust stroke rlntake elosed Exhaust open rFlstun travels up Exhaust ts expelled Ends 1 mm: tumult - Distributor Waltz otmtqz Between the end ofthe Exhaust Stroke and the start ofthe lntake Stroke Both valves are partway open bney at the same ame Helps to purge exhaust 'um the eyltnder and ll tt wtth Air/fuel mtx rOccurs at TDC @i o @@ @99 0an stroke Starts 1 mm: taming * Starts at TDC wtth rotor pumtmg at #l rlntake open Exhaust elosed rFlstun travels down rCyllnder lls wtth Atr/fuel mtx D Cnmgmsslnn Stmkz rlntake elosed Exhaust elosed rFlstun travels up rAJr/fuel mtx ts compressed Make sure the engtne cannot start (Key off and cotl wtre gounded) parktng brake on, wheels blocked and trans tn park or neutral Valve cover off Locate valve overlap by rotattng the engtne wtth a breaker bar Watch the rocker arms to ftnd when the exhaust valve starts to close and the tntake valve to starts to open when they are equal then you are at valve overlap on that cyltnder By locattng overlap tn the cyltnder oppostte #l tn the ftrtng order, you also locate TDc tn cyltnder #1 Your rotor should potnt at the wtre for #1 when the oppostte cyltnder (#6 tn the above ftrtng orders) ts at overlap The reverse ts also true (Thls helps tfthe other valve cover ts easterto remove) By locattng overlap tn cyltnder #1, you also locate TDc tn the cyltnder oppostte #l tn the ftnng order Your rotor should potnt at the wtre for the cyltnder oppostte #1 when #1 ts at overlap As you sltde the dtstnbutor tnto place the rotor wtll tum sltghtly If tt ends up offof#l, pull tt out, tum tt 1 tooth and try agatn ttll lts rtght Install the hold down and ttghten tt so that the dtstrtbutor wont move on its own, but can be turned by hand when setttng the ttmtng Thts should get the dtstrtbutor close enough to start the engtne (Aerreconnectlng everythtng) Then set the ttmtng accordtng to the manual You can also use thls method to check the flrlng orda of the camshaft Locate valve overlap tn # 1 On a V8, rotate the crankshaft 9o degees (120 degees for a 6) tn the dtrectton that the engtne normally tums Note whtch cyltnder ts now tn overlap It ts next tn the ftnng order Repeat for each cyltnder unttl the order ts determtned Cummnn akes m avoid rAssumlng that the # 1 mark on the cap was wtred to the # l cyltnder rermg the dtstnbutor cap wtth the rotatton backwards rUslng the wrong numbertng system for the cyltnders Ford ts dtfferent (Better) than chevy rConfuslng whtch wtre actually goes to whtch cyltnder rUslng the wrong ftrtng order for the cam that ts actually tn the engtne rlnstalllng the dtstnbutor 180 degees off 8- 8mm