Idle Arms and Timing chain Housing questions

[Hill3312]

Hello,

There are two things that are concerning me with my rebuild. The nuts that are used on the inside of the timing chain housings that hold them to the motor, and idler arm movement on the shaft in the housing.

- First thing, the nuts. My book calls for "vibration resistant egg-shaped locking 13mm nuts" to be used on the inside of the timing chain housings. I didn't have any, so I went to my local performance Porsche shop and spoke to the neighborhood guru to try to get the right nuts. He says he just uses regular 13mm nuts and handed me some. Will this be okay?

- Second thing, idler arms. The book says to just install them by putting a few drops of oil on the shaft and sliding them on. I noticed that with the tensioners installed, I can still move them forward and backwards on the shaft (pull them in and out). Are they supposed to have a small range of motion?

I have the upgraded oil fed tensioners and upgraded idler arms.

[Jack Stands]

You don’t say what year your engine is from, but the answer will depend a bit if you have the original style tensioner or the pressure fed ones. The bearing for the idler arms was enlarged when they switched to the pressure fed tensioner. Some movement makes sense as you don’t want them binding up on the posts. The pressure fed tensioner update kits used a spacer on the idler arms, so there may be some play. Supertec offers a modification to the idler arms that increases the bearing surface of the idler arms that’s an excellent upgrade.

Don’t know about the nuts, but a touch of Loctite shouldn’t hurt. Otherwise, the deformable nuts could certainly be used if desired. McMaster-Carr carries these in metric.

[Flat6pac]

There is a small movement in and out allowing the chain to center while running. Think about it, there has to be movement because there is parallel chain adjustment.
Inside the motor use regular nuts and thin waves spring washers. I have never removed prevailing torque nuts inside the motors, just on the flange perimeter from the mid eighties.
Bruce

[Trackrash]

The factory used regular nuts inside WITH wavy washers. Blue locktite would not hurt.

There should be some side to side play in the idler arms. This will allow the sprocket to center on the chain.