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Hopefully I can get a confirmation on the following info:

The 964 and earlier cam sprockets have a bunch of holes around the perimeter and the dowel is used to fix the timing.

The 993 uses a cam sprocket with only four holes and no dowel. Only the friction of the cam bolt is used to fix the timing.

Yes, I see the difference between the earlier 964 style sprockets and the 4 holed 993 type. I am just not sure why they show a woodruff key and dowel on the '97 993 PET. If I could ever get the nut off the sprocket, I could easily determine this for myself.
thanks again.
Rick
'78 930

The key is for the flange. Not sure about why PET shows the dowel. As Chris said earlier you can remove your sprocket bolt with an impact wrench. Use an electric one if you don't have an air supply.

I will remove the sprocket and report back. From what I can tell the only difference is the sprocket. Every other part number in the assembly is the same back to '89. I may need to add or subtract shims to make sure the sprocket alignment is dead on.
thanks again
Rick
'78 930

Quote:

Originally posted by rick conrath
I am a little confused here. When I check the part numbers and illustrations in my PET, the 964 and 993 share the same sprocket numbers,wwodruff key as well as dowel pins at least up until '95. Chain wheel # 901 105 546 02 appears to be used well back into the' 80's. So if I am backdating to 964, what year is the benchmark? My '97 sprocket assembly also shows dowel pins and the basic hardware setup as the earlier '89 c2. I can see no difference between the 993 and c2 other than the tensioner setup and hydraulic rocker arms. What benefit is there for me to backdate to 964 style?
Rick
'78 930

Rick you are correct the normal '95 993 used the same sprocket arrangement as the 964. This changed on the '95 RS and '96 on vrams. The thing to remember w/ PET is that they use a single diagram for multiple models.

A '97 993 does not have a key, the sprocket is perfectly free to rotate relative to the cam.

Here are a few pics of my spare '97 993 cams and sprockets
http://forums.pelicanparts.com/uploa...1088973370.jpg

http://forums.pelicanparts.com/uploa...1088973410.jpg

http://forums.pelicanparts.com/uploa...1088973438.jpg

http://forums.pelicanparts.com/uploa...1088973471.jpg

When backdating there are 2 ways to do it, the easist and best is to buy cams w/ the correct end machining for the older style sprockets. Thats what I did, you probably want different cams anyway , right?

The other is a kit to update the existing cams, but this entails some machining.

Well, I have two sets of 993 cams. The spare set that I have in a box has a keyway cut in the end of it, and two different sets of numbers. On the snout #993 105 09, on the body #964 246. Are these of any use with the earlier 964 style sprockets, or will I have to get a new set of cams (or have these machined)? I would imagine that they have some value as cores as opposed to just being paperweights.
Thanks,
Rick
'78 930

Bill: Could you not have used the earlier style pre '95 993 sprocket setup? The camshaft has a keyway on it to accept the inner flange #901 105 583 01 which will accept a dowel setup like the earlier 964.
Thanks,
Rick
'78 930

#993 105 09 is the '96-98 vram cam sans keyway(if there is a keyway it was machined in aftermarket) used on M64/21 - 24 engines. That is the cam in my post above

#993 105 07 is the '94 - 95 non vram cam w/ keyway, used on M64/5 - 8 engines. These cams use the same sprockets as the 964

Quote:

I would imagine that they have some value as cores as opposed to just being paperweights.

i haven't found a market for them

Quote:

Yes, because I bought new cams w/ the earlier snout set up for the earlier setup.

Thanks for the advice...I have it figured out now. Who knows what the finish on the 993 chain cases is? They look composite, but I thought they were magnesium. My set looks really,really bad and I am not sure that they can be cleaned without using blasting media.
Any advice/
Thanks,
Rick
'78 930