cam timing spec

[Mike M]

Hey Everyone....
I have a 69 911s with 2 litre engine.The previous owner had the case and heads machined to accept 2.7 pistons and cylinders. When timing cams,which I think are 2.7 cams,is the timing spec simply the 2.7 spec? The heads are original 2.0 litre S heads. Any help would be appreciated.
Thanks

[john walker's workshop]

if they are indeed 2.7 cams, they would be adjusted to 2.7 specs. (basically .5 mm). it's hard to tell what cams you have sometimes because the number stays the same regardless of what grind is put on them. good grinders stamp their number on the end. so if there's no extra number on the end, chances are good that it's stock.

[Mike M]

john walkers workshop....
thanks for your reply... I do not know the camshaft part numbers,all it says on the FAT Perfomance invoice is ,RT. 911S camshaft, Left 911S camshaft(300.00 each in 1980). Last time we had the engine apart, we re timed the cams using a spec of 5.20, so I guess we are on the right track. Any thoughts?

[john walker's workshop]

that spec would relate to an early S cam, not a 2.7 cam. 5.2 is different than .5. what are the casting numbers on the cams?

[Mike M]

john walkers workshop....
I don't know the casting nos. The guy that reassembled the engine says the cam timing was set to 5.20.Was this done incorrectly? What will be the result?

[john walker's workshop]

well, if you have early S cams, that would be ok, as long as the pistons have valve pockets to prevent piston/valve contact.