New Timing Chains - Broken Snap Ring

[Dauner]

I replaced my timing chains last week based on lots of feedback from the forum last fall. See previous thread here:

Need Help: Timing Chain - pics attchd

Everything went fairly smoothly. I followed the procedure in the bentley, rotating cams "outward" roughly 45 degrees to minimize chances of piston valve interference. As a note, the right camshaft needed to be closer to 1 o'clock instead of 2 o'clock. I definitely hit the #6 intake valve with right cam at 45 degrees. The bentley says if feel interference "stop, and rotate camshaft". That's easier said than done. I ended up reinstalling the camshaft sprocket and pin, and turning crank/chain/sprocket. it basically jumped to the 1:00 position, and transferring the chain through the case was smooth sailing after that. I didn't have any problems with the left side (except that it would be nice to have 3 hands, two on each end of chain and one turning crank). I did the left side first, which took me about 4 hours, although some of that was because I videotaped the entire process with commentary (including jabbing a jewelers screwdriver in to my finger tip trying to remove the link plate I thought I had ground off). I'm hoping I can get time to edit the long and boring video down and post on youtube. Tons of little nuancy things that are not mentioned anywhere, including Bentley, forum., etc.

Here are a couple of phone pics of post installation:



To my problem statement: The Iwis chains that I bought had a slightly different master link configuration than what is shown everywhere. Instead of a one piece clip that holds master link in place, each chain had two rediculously small snap rings, one for each pin. 3 went on fine, one of them actually bent/distorted. Although the snap ring doesn't work very hard, it has a tremendous amount of responsibility, so I'm thinking I need the master link kit at Pelican. I'm fairly confident that everything will be interchangeable (and the one piece clip seems like a big improvement over the tiny snap rings), but would like some confirmation. Has anyone else ever had one of the snap rings yield beyond yield strength? In the pic of the right chain, you can see the snap rings at roughly 11:00 from the camshaft sprocket.

I have all of the tools to time the camshafts, and practiced a number of times before I disassembled anything. I think I've got it down pretty good. Had a friend make a Z block for me at work in a half hour. Also borrowing a dial indicator from work. The thing I'm the most concerned about is (embarrasingly) getting the right feel/drag for proper 0.004" valve adjustment. I've adjusted valves before, but not on the 911. The importance of it, and the limited access, even with the special tool, have me nervous.

I also video taped my engine drop, mostly because I couldn't find any videos on the internet doing it my way (in the garage cramped between our other two cars, in the middle of winter, ATV lift with plywood, etc.)

Feedback on the snap rings greatly appreciated.

Thanks!

Mark

[timmy2]

I recently replaced a broken head stud and all the others while I was in there...
I found that using the backside method as well as the standard method for setting the clearance worked really well. I am now doing the 500 mile oil change and valve adjustment (Just dropped the oil tonight) and I will be checking and adjusting them using both methods again. (Backside go-no go method as a check) Getting that feeler gauge in there is a real trick but after a couple of them you'll get a method down.

[Dauner]

To Close the loop: I called Pelican and there was indeed a design change in the Iwis timing chains in that the retaining method is two small snap rings instead of the one "make sure you install in the correct orientation" clip like is shown in current Bentley. I ordered a couple of master link sets that should come with the "E clip" snap rings.

Mark