1975 911S cam chain tensioner upgrade

[steve65cobra]

I am new to the forum but have been a Pelican Parts customer for several years. I am finally able to spend some time on my beloved 1975 911S and the first order of business is the cam chain tensioner upgrade...I am not sure if this was done to the car (it has about 101K miles). Two questions: 1) What is the simplest way to determine if this was done by one of the previous owners; and 2) What book(s) do y'all recommend to assist me in doing the job myself? I am a competent do-it-yourselfer having rebuilt many engines (including Mercedes diesel) and am not afraid to tackle this job, but I have learned it is far better to solicit comments from those who have already done this job and learn from their insight.

[Targalid]

This is one of the projects in Wayne Dempsey's 101 Projects for your Porsche 911. This fine book is available from Pelican. Don't leave home without it.

[fanaudical]

+1 on the book. I also recommend Wayne's Porsche engine rebuild book. Both contain significant detail and pictures. You should have a good understanding of what you might get into by reading the books.

Look at 101 Projects Website for more info.

The hydraulic tensioners should have small steel oil lines feeding them through the chain housings.

[HarryD]

If you are looking to verify that you have oil fed tensioners, you can see them since the oil lines are visible.

Right side will look something like this:



Left side will look something like this:



Note on both sides there is a line that tees off of the cam tower oil lines and goes into the side of the chain boxes.

[Walter_Middie]

Steve,

Do some more research on the upgrade before jumping in. During my engine rebuild, I considered removing the oil fed chain tensioners and going back to the original system with safety collars. The upgrade certainly won't hurt you, I just don't think you will gain anything over originals with safety collars. The oil feed tensioners can fail just like the originals - the trick is to make sure a failure won't damage the engine - like collars on the original system, and the Woods modification to the oil fed tensioners.

[HarryD]

Originally Posted by Walter_Middie

Steve,

Do some more research on the upgrade before jumping in. During my engine rebuild, I considered removing the oil fed chain tensioners and going back to the original system with safety collars. The upgrade certainly won't hurt you, I just don't think you will gain anything over originals with safety collars. The oil feed tensioners can fail just like the originals - the trick is to make sure a failure won't damage the engine - like collars on the original system, and the Woods modification to the oil fed tensioners.

I would add that I have been told that if you have the later oil filled units (930-xxx-xxx-xx), the updated chain wheels and safety collars, the pressure fed ones do not add that much more to the party.