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Cosworth Cam Timing

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Old 21-09-2004, 03:28 PM
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CosRush
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Default Cosworth Cam Timing

Ensure Cam sprockets are aligned.



Ensure Crank Pulley is aligned to the TDC Peg.



Ensure Auxilary Pulley Pointer is central to the Half Circle.



It all should like this.



Belt tensioner


Belt tension
Old 01-10-2004, 03:00 PM
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Dave Henshall
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just to add, as a rule of thumb, in the longest run of belt.. there should be just enough tension in it to be able to twist the belt through roughly 90 degrees. as a final check wind the engine round twice on the bottom bulley with the plus out and check the alignment of all the above points again
Old 01-10-2004, 03:11 PM
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Don't you have to feed the belt round the pulleys anticlockwise too ? Starting at the crankshaft ?

Cosrush, these are superb pictures, about time we got something better than ford's low res diagrams
You might just have saved a few peeps some valves, etc...
Old 01-10-2004, 03:12 PM
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Originally Posted by frog
Don't you have to feed the belt round the pulleys anticlockwise too ? Starting at the crankshaft ?

Cosrush, these are superb pictures, about time we got something better than ford's low res diagrams
You might just have saved a few peeps some valves, etc...
Edited to say that if the above is wrong I will take it out before someone gets in trouble on my account
Old 01-10-2004, 03:15 PM
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Thanks

I took them before i dismantled mine, and thought others could benefit from them...
Old 01-10-2004, 03:19 PM
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By the way...

Those pictures were taken in my old kitchen where i dismantled it

My wife didn't mind though
Old 01-10-2004, 03:41 PM
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and if u notice , ever so slightly the left hand cam pulley is just out of plonk a smidgin - this is what justifies the need to vernier timing pulleys, if you are running a wild cam and it was out by that very small amount , you could end up with bent valves. on a std engine with std cams the EXACT mechanical timing is not quite so crutial.
Old 15-12-2004, 09:26 AM
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foreigneRS
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i have a couple of points toadd, based on experience.

1) the crank pulley should be lined up so that the leading edge of the square peg is in line with the blade of the timing marker, rather than the centre of it as pictured (according to the YB service manual).

2) tensioner. the manual says to tension the belt by turning the tensioner clockwise and locking it. if you do this, the belt is trying to turn the tensioner anticlockwise which has a loosening action against the locknut. i had this happen that the locknut loosened and the cambelt loosened and jumped and fucked all 16 valves.

if you tension the belt by rotating the tensioner anti-clockwise, the belt pushes against it and keeps it tight against the locknut.
Old 15-12-2004, 09:38 AM
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i've re-read the manual, and point 1 is described as the 'flank of the tooth', whatever that means.
Old 15-12-2004, 09:57 AM
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from doing a google, the 'flank of the tooth' would seem to be the leading edge, rather than the flat top.
Old 11-01-2005, 09:51 PM
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is this the same for a greentop 4x4 saff engine then (200 block) ?
Old 17-01-2005, 11:49 AM
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Couple of points to add:

1) Trailing edge is the correct TDC point.

2) The tensioner MUST be done clockwise to centralise the belt in the runners.
Old 17-01-2005, 06:51 PM
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Ive edited these pictures a little.
Hope this is an improvement, and clears up any ambiguity

***these have now been amended at the top of tis post***
Old 17-01-2005, 09:25 PM
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Originally Posted by Stu @ M Developments
Couple of points to add:

1) Trailing edge is the correct TDC point.

2) The tensioner MUST be done clockwise to centralise the belt in the runners.
and if you try to tension it anticlockwise, the belt rubs on the thermostat housing
Old 17-01-2005, 09:30 PM
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CosRush,
Ive edited these pictures a little.
Hope this is an improvement, and clears up any ambiguity
Nice edited pics.. very clear indeed
Old 19-01-2005, 09:30 AM
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Would anyone mind if I add my two pence worth?

Don't assume that if the Aux Drive pulley is aligned as shown that the dizzy will be aligned correctly - Take the dizzy cap and shield off, put the rotor back on and align the centre of the rotor contact with the mark on the rim of the dizzy

Neil.
Old 26-01-2005, 02:17 PM
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Originally Posted by Stu
The tensioner MUST be done clockwise to centralise the belt in the runners.
i don't understand what you mean Stu. Do you mean where the belt comes out of the front cover near the crankshaft pulley?

i've got my tensioner done up anticlockwise, and the belt does not contact either the front cover or anywhere near the thermostat housing. but you've got me worried now. but i really don't want to change it as to me it's risky when it's clockwise and trying to undo it's locknut. i know that's how ford and cosworth say it should be done and that's how thousands are running.

CosRush, great pics. has clarified the crankshaft tooth position brilliantly as well.
Old 26-01-2005, 02:33 PM
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Originally Posted by foreigneRS
Originally Posted by Stu
The tensioner MUST be done clockwise to centralise the belt in the runners.
i don't understand what you mean Stu. Do you mean where the belt comes out of the front cover near the crankshaft pulley?

i've got my tensioner done up anticlockwise, and the belt does not contact either the front cover or anywhere near the thermostat housing. but you've got me worried now. but i really don't want to change it as to me it's risky when it's clockwise and trying to undo it's locknut. i know that's how ford and cosworth say it should be done and that's how thousands are running.

CosRush, great pics. has clarified the crankshaft tooth position brilliantly as well.
Personally, I too agree with your reasoning, and I deliberately tried to tension mine anticlockwise when I last changed the belt, to see how it would fit, and the belt rubbed firmly on the thermostat housing flange/bolt in that position... (mine is 4x4 if it makes a difference to the thermo housing..)
Old 26-01-2005, 02:43 PM
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Thanks for the comments on my pics....

If they help anybody then thats got to be good
Old 30-01-2005, 04:23 PM
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Originally Posted by richm
mine is 4x4 if it makes a difference to the thermo housing..
yes it does rich, well they're different parts anyway, so they could well be differently shaped in that area.
Old 06-01-2006, 05:59 PM
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For anyone on verniers tha arent clear on where the pulleys should line up or might have been apart and put back wrong, the woodruff key is opposite the triangle, so starting point should be the two woodruff keys facing away from each other (ie the opposite way to the triangles, so facing apart not facing together)
Old 26-03-2006, 08:15 PM
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Great thread

I am tackling my belt/tensioner this week

Thanks
Old 12-04-2006, 12:45 PM
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Originally Posted by chip-3door
For anyone on verniers tha arent clear on where the pulleys should line up or might have been apart and put back wrong, the woodruff key is opposite the triangle, so starting point should be the two woodruff keys facing away from each other (ie the opposite way to the triangles, so facing apart not facing together)
good point

on kent verniers, the word 'cams' is in the position where the arrows would be,like this ( kinda hard to see sorry )



http://img.photobucket.com/albums/v2...s/IMG_3811.jpg
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