timing worries...help
18 March 2007, 04:41 PM
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timing worries...help
me and a friend have just fitted a cam belt to a '94 wrx.
the engine is out of the car so nice and easy to work on.
the thing is - putting the belt on and lining up all the marks correctly (has lines on belt also) was easy enough, released the tensioner and everything still lined up perfectly!
but when turning the crank over by hand all the timing marks (on pulleys) are way out and different with every rotation????
engine has probably been turned over about 20 times or so now with no valve/piston interferance.....but marks still way out?????
any ideas what is going on?
the heads have just recently been skimmed and standard gaskets.
the tensioner seemed fine (compressed it vertically also)
(non subaru belt)
cheers guys
the engine is out of the car so nice and easy to work on.
the thing is - putting the belt on and lining up all the marks correctly (has lines on belt also) was easy enough, released the tensioner and everything still lined up perfectly!
but when turning the crank over by hand all the timing marks (on pulleys) are way out and different with every rotation????
engine has probably been turned over about 20 times or so now with no valve/piston interferance.....but marks still way out?????
any ideas what is going on?
the heads have just recently been skimmed and standard gaskets.
the tensioner seemed fine (compressed it vertically also)
(non subaru belt)
cheers guys
18 March 2007, 05:22 PM
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What you're seeing is totally correct, and nothing to do with skimming the heads, it's because the distance between each pulley is not equal, so as you rotate the crank, you'll see the marks go offset.
Rotate it enough times, (don't recall how many) and they'll match up again.
Mark.
Rotate it enough times, (don't recall how many) and they'll match up again.
Mark.
18 March 2007, 05:26 PM
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What you're seeing is totally correct, and nothing to do with skimming the heads, it's because the distance between each pulley is not equal, so as you rotate the crank, you'll see the marks go offset.
Rotate it enough times, (don't recall how many) and they'll match up again.
Mark.
Rotate it enough times, (don't recall how many) and they'll match up again.
Mark.
are you sure they can throw cam pulleys out this much? noticed almost 180 degrees out on 1 inlet cam (pass side)
I'm worried about conflicting news now
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18 March 2007, 05:27 PM
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Meant to say that skimming the heads will change the actual cam timing, but 99 times out of 100 it's out on a standard engine anyway.
The only way to get the "correct" cam timing, is to set it up properly, and to do that, you need the right equipment, adjustable pulleys, or bolt them up GrpN style.
Mark.
The only way to get the "correct" cam timing, is to set it up properly, and to do that, you need the right equipment, adjustable pulleys, or bolt them up GrpN style.
Mark.
18 March 2007, 05:31 PM
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Just think about the length of the belt between the two inlet cams, and the two exhaust cams, then between the cams on each head.
You get some timing marks that are just a few inches apart, and some that are much more.
Mark.
You get some timing marks that are just a few inches apart, and some that are much more.
Mark.
18 March 2007, 05:45 PM
#11
Its just like Mark says mate, I did the belt on my own car two months ago and encountered this problem. I rotated it about 10 times before I realised what was going on, thought I had trashed the engine. Throw it back in and enjoy, I hope you fitted a new oil pump aswel.
18 March 2007, 07:30 PM
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AS above,But regardless of the markings on the belt.It is a good idea to check the marks on the cams are all lined up corectly when the crank mark is in the right place. Just remember if the crank marking is right the cams may not be and just needs another complete turn.
19 March 2007, 12:58 PM
#14
Just to put your mind at rest, 8 thou is nothing, if that is the correct figure in terms of head skimming. An 8 thou skim would be to get a fully flat surface for the gasket to pull down on and is not signifigant in terms of compresssion ratio or cam timing.
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