working on 72 911t mfi

[tharbert]

I restarted my car last weekend after about an 8 year hiatus. After the initial euphoria I started paying a bit more attention and heard a racket from the left cam chain tunnel. I pulled the covers and found a chain tensioner guard had failed - broken! I pulled the pieces out and ordered a new set from pelican. I was out in the garage trying to fit the new pieces and had a couple questions:

I cleaned up the tunnel covers with mineral spirits and some light brass brushing and found:

The metal had corroded under the patina of grime. Structurally, it looks fine but the surface basically looks like $hit. What type of metal make up the the covers? How does one protect from further of corrosion short of replacement? I'm guessing I can brush/polish it up but with the deterioration of the primary external coating, the next step is paint or powder coat?

Second, Wayne's instructions say:



To raise both tensioners to their highest position, I slackened the chain from each cam shaft axel. I turned the motor over by hand as suggested. The right site had considerably more space above the right tensioner arm comparied to the left tensioner arm:

Left:



Right;


I wanted to double check... Is this good, bad, or just plain old OK for a 72. Should I try to even them out in some way?

[coldstart]

Firstly, I am going to state that I am not the expert in this area BUT I think that you should stop further work on the tensioners and listen to the experts on this board. You could very easily bend some rods and ruin your engine if you are not careful with your timing chains.

Some basic questions:

1. Did you clamp the chain in position when you replaced the tensioner? If not, you likely need to redo your cam timing.

2. To me, it looks like you have tensioner guards on your tensioner. Do you know if these were added at some point?

3. There are debates about the safety of pressure-fed tensioners vs. mechanical tensioners vs. solid tensioners (more race application) but you should at least consider installing pressure-fed tensioners at this point.

4. What prep did you perform before you started the engine after it sat for 8 years? Do not start it again without following the expert advice on this board!

5. What shape is the rest of the car in? Brakes, tires, rust are big safety issues....

Post pics of the car!!!! 72 is a great year for 911s so get her running properly again and out on the road! All the best with the project and listen to Milt, TRE, JW and the other experts here.....

[Flieger]

The timing chain covers changed from Aluminum on the early cars to Magnesium by the years including yours. This was to save weight and preceeded the change to a Magnesium case. Porsche then changed back to Aluminum for everything for the SC-Carreras for durability and strength.

[tharbert]

I appreciate your concern about my timing... I don't believe it's an issue here. I haven't pulled any gears or chains off. I merely opened the chain tunnel to check on low RPM noise.

1. Didn't remove tensioner - did replace broken guard.

2. Didn't know guards were in there until I popped the cover off.

3. Haven't researched alternatives yet but, yes, something needs to be done here.

4. Starting Prep? See post here (Yes, I know it's a 72. I couldn't change the post title)

5. I totally agree! This car will not see the road until it's safe to do so. The body is in very good shape. There are a few places where rust is a real issue. I plan on replacing most of the brake lines. My last box from Pelican included replacemenet flex lines. I also intend to move to DOT 5 so all the lines will be flushed. I'm on the fence about rebuilding the calipers and MC. Will cross that bridge later. The rims are 70's style aftermarket, not Fuchs. Tires will be renewed but not until after I tackle the body work.





And lastly, I fully intend to use the expertise on this site. I haven't ask that many questions because so many others have beaten me to it. I have been reading a lot of threads. So many threads, so little time!

[RWebb]

could try a soda blast and then sand them flat, using finer papers until pretty - coat with Gibbs or Corrosion Block. best would be a Tetyl waxy type coat.

they will corrode quickly even in a garage....