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davevr6car

Cams pullies

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Hi,

does anybody know how to tell the difference between a 110' inlet, 100' exhaust and 104' cam pullies.

The marks have worn off, ie Blue & red dots.

cheers

Dave

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From Tim Engel's Cam Data.XLS

A 110° MOP red dot pulley installed backwards yields a 100° MOP (blue dot). Initially Lotus produced separate 110° MOP red dot and 100° MOP blue dot pulleys. Later they consolidated and produced one 110°/100° MOP, red/ blue dot pulley. As an installation guide, a raised bump was cast on one side of one spoke. When the pulley is installed on the EXHAUST cam with the raised bump facing FORWARD, the timing is 110° MOP. When the pulley is installed on the INTAKE cam with the raised bump facing BACKWARDS, the timing is 110° MOP. In either case, reversing the pulley gives a 100° MOP (blue dot).

You want the dot next to "IN" facing the front of the engine on the intake cam, and the dot next to "EX" facing the front of the engine on the exhaust cam.

engine%2520s.jpg

Similar to this, but I have a green DOT on my intake.

P4011850.JPG

P4011849.JPG

Be careful! looking from the back of the engine, in-situ, the markings will be backwards!

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Cheers Travis for your in depth reply.

The problem I have is that I want to replace the standard timing from 110' mop on the inlet and 100' mop exhaust to both 104' mop by using the oil pump pulley and another another 104' pulley i purchased from the internet, but the one from the internet does not match up with the oil pump 104' pulley. I'm working on rebuilding my S4s engine at the moment after it spun a big end bearing and was hoping to carry out this cam up grade as part of the rebuild. Would I be correct in saying that the green dot 104' pulley was used on the 2.0L turbo exhaust as well as the oil pump pulley on all 910 engines. The red dot 110' was for inlet on both 2L and 2.2L turbo inlet cams. The blue dot 100' for exhaust cam on the 2.2 turbo exhaust cam. I may check for the bumps on my cams that you mentioned above.

Could I use the woodruff key slot in the cam pullies as a datum point, and measure from here to the dot/dimple in degrees, to figure out which cam is which?

cheers

Dave

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Dave,

The pulleys are almost certainly all made form the same casting. The location of the woodruff key slot is the only difference between the pulleys, but there is a very small visual difference. The dot itself is not a datum point, but the tooth it is adjacent to is.

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