CEL=Check Engine Light. I was paranoid about this until I read the manual 'cause mine didn't come on. Now I've been on the forums a while I'm glad we don't have it!

If you look in the UK manual the turbo's have it but not NA (normally aspirated) cars.

 

Doh! Yes, that acronym is a bit obvious when you think about it! One less thing to worry about! ;-)

 

The keyway is to lock down an inner indexing sprocket that sits inside the outside sprocket that the chains run on. The outside sprocket is free to spin on the cam when its not locked down ; its the rotational position on the cam that sets the timing. On the older cars when the timing is set the position of the outside sprocket is determined and a pin is inserted between the two spockets to hold it in that position until it can be bolted down. There are a series of holes drilled in both the inner and outer sprockets for this pin. Anyways on the 993's there are no pins, the timing is set via expensive factory toos. They eliminated the inner sprockets totally. This means its difficult to time the cams using the old way (its still possible but painfull) without the factory tools. There is also talk about, because there is not positive lock on the 993 cams, that the cams could slip. Mine were fine but some people claim that theirs had slipped.

Cheers,

Mike

 

Thanks Mike,

I now understand. So how does this link with these comments about using old 964 gear wheels?

Cheers,

David

 

The 964 sprockets (gear wheels) have the indexing holes in them. A picture might help....look at part 5. It requires a key and a keyway. Part 4 on a 993 is a different design and does not have the index holes for the lockpin.

 

Thanks Mike,

You could probably teach this stuff to other people if you ever fancy a career change!

Cheers,

David

 

Mike,
could you tell me if it's possible to see, without dismounting the cams, if they have the key way?

David if you're interested, here's a post from 993RS about valve timing

 

Thanks JP.

Interesting reading. I have an early 1995 car so perhaps I have the earlier bits?

Cheers,

David