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TDC QUESTION


2fast2six
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TURNED OVER CRANK TILL TDC. DOWEL PIN ON CAM GEAR IS SLIGHTY TO THE LEFT OF TOP DEAD CENTER AND THE CRANK PULL MARK IS LINED UP -10 DEGREES BEFORE TDC

TRYING TO REPLACE MY CHAIN IS THIS CORRECT? OR SHOULD THE CRANK PULLY BE RIGHT IN THE MIDDLE AT 0? IS -10 DEGREES BTDC OKAY?

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ok so i moved the crank till it was lined up at zero and the punch hole on the cam at TDC. took everything apart and pulled off the cam gear to find the dowl pin sheared off.... so when i pulled the cam gear off, the dowel pin hole on the cam is a little passed 12 o clock and the cam gear itself was right at 12 o clock. what should i do? the chain is off...

 

crank is lined up at 0 on crank pully. cam is slighty passed 12 o clock.... is that okay just line all the timing chain links up? or do i just need to rotate the cam clockwise 2 times to get back to TDC since its passed TDC now?

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ok, listen carefuly ,block the tentioner from pushing out too far,, walking the cam gear off the chain, marking the tooth and link where it is at NOW , replace the roll pin with a new one , once the new pin is install'd and the piece remove'd from the cam,be sure to install the cam gear right back in the oreg marks, it was in when you remove'd it

 

lift the cam gear and chain forceing the tentioner to retract,, now still holding the gear up rotate the crank with one hand and a wrench clockwise a little untill the pin aligns with the hole in the cam , push the cam gear onto the cam,, install the dist drv and bolt ( to stop gear from poping off )

 

you can rotate the engine backwards by useing a screw driver and a small piece of wood,,place the wood on the head on dist side now use the tip of the screw driver to back up the cam gear untill the crank is at TDC ,,now check the cam gears pin location , if slightly before 12:00 your good to go,, if it's a good ways before 12:00 your one tooth off at the crank .

 

to double check al this rotate the crank two turns back to the cam pins just before 12:00 location,,do not look at the crank TDC at that time only watch the pins location,,when your satistify'd the pin is in porper location,,look at the TDC marker

 

1 tooth off at the crank will make aprox 10 degrees differance at the crank pully

if the crank TDC mark is ATDC aprox 10 degrees , your one tooth off ,,to fix this remove the cam gear from cam BUT DO NOT alow it to drop (the cam is in proper position at this time you do not want to move the cam,,thats why you remove the gear and chain ) , carefuly turn the crank with a wrench back wards to 10 BTDC ,, once the TDC mark is align'd ,, walk the cam gear arround one link back wards or in the oposite direction of normal rotation , at this point you ignore the chain and gear marks you made eariler , ok got the chain back on the gear,, pull up wards on the gear and chain and rotate the crank to TDC and slide the cam gear back on the cam , install the distdrive and bolt snug it so the gear can't pop off,, rotate the engine 2 times back to TDC and recheck you work , if every thing is now in alignment,,tourqe the cam bolt down

 

this is the perfict time to install the dist,,as you can see the dist alignment marks as you install the dist,,, rotate the dist aprox 1/4 " advance'd and snug the bolt the engine should be close enought to fire up and run

 

hope that helps

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