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[cavell]

got an 02 saturn vue with a 3.0 motor.
anyone have info on cam markings? ID's?
they all have the same casting number.
but the only ID on the cams is a  GC number
such as GC19, GC25, GC26, GC27
there is no A or E markings. no markings on etching on end of cams.

[cavell]

main question is about ID'ing the intake or exhaust cams
i measured a .025" difference in lift between them
i had the cams off to remove headbolts and am 99% sure they are in proper place
but, i assumed it would be easy to verify with cam markings. but there are none that make sense to online info

[frostbite]

The GC numbers are irrelevent

[cavell]

You are the man!
E1, A2, A3, E9

[cavell]

at TDC, cyl #1 has closed valves. but cyl 3 and 5 may have the cam trying to open valves or possibly
close valves? so at TDC, cam #1 may have considerable spring tension trying to rotate it?
cam 3 and 4 are slack at TDC. thats just the way it is?

[Nick W]

why is it that cams 3 and 4 are at 12oclock and have no valve spring tension to try and rotate them
while cams 1 and 2 are also at 12oclock but the cam lobes are trying to open some valves?
such as cyl 3 or 5
so, cyl #1 is at tdc. cyl 3 is not and cam is trying to open that valve?

What else would you expect on a four-stroke, DOHC V6 engine? The whole point of a multi-cylinder engine is that they will all be at different parts of the cycle.

[cavell]

Friend has a Toyota 1mz-fe 3.0 dohc. Each head has 1 front sprocket and rear of cams has gears that mesh together. You do not have to lock cams in position when belt is removed. Some of the valves must be in open position at #1 cyl tdc?

[Doctor Gollum]

That's just a different way to drive four cams, net result remains the same

[TheBoy]

at TDC, cyl #1 has closed valves. but cyl 3 and 5 may have the cam trying to open valves or possibly
close valves? so at TDC, cam #1 may have considerable spring tension trying to rotate it?
cam 3 and 4 are slack at TDC. thats just the way it is?

On a 4cyl engine, for example, at TDC, you'd expect all valves closed (almost).  On a 6cyl engine, because there is a firing stroke every 120 degrees, that is not the case - as cyl 1 is at TDC, other cylinders will be at different stages of the cycle.

Hope that makes sense.

[Marks DTM Calib]

at TDC, cyl #1 has closed valves. but cyl 3 and 5 may have the cam trying to open valves or possibly
close valves? so at TDC, cam #1 may have considerable spring tension trying to rotate it?
cam 3 and 4 are slack at TDC. thats just the way it is?

Yep, that's correct (as for pretty much every 1-2-3-4-5-6 firing order V6).

What you will find is that the cams on 1-2 bank will try to move off mark with the locking tool removed (friction does generally hold them, just)

[cavell]

true, a simple timing belt job is made more complicated when you remove the sprockets from the cams and than remove the cams from the head. this will be the 3rd timing belt on a vue 3.0 for me so i do recall that cam 1 and 2 are trying to move with belt off. you set sprocket mark to about 1/2-1 tooth before mark and than when you tighten the tensioner wheel it pulls them into position.

[cavell]

Question about belt tensioner. It has offset hub so twisting CW/CCW will advance/retard timing. can you adjust timing so it might be before or after timing Mark? My 3/4 cams are dead on. But 1/2 are a smidgen before perfect.