Chain Tensioner Install Question

[jungspike]

I am in the middle of swapping out cams (putting in 20/21s in place of my GT2s).

After timing cams, when installing the chain tensioner, the vice grips (holding tension on the idler arm) came loose before I got the OEM/oil tensioner in place--putting slack in the chain. Wayne's book warns that this may affect cam timing. After getting the tensioner in place, I checked cam timing, and it is still good.

1. Am I OK?
2. If my cam timing is valid with the oil tensioner, then why not do cam timing with the OEM tensioner? Why use vice grips or Stomski's mechanical tensioner?
3. When doing cam timing with a mechanical tensioner, how much tension should I have on the chain? Is it more than the spring in the OEM tensioner? I could find no value/technique specified.

Thanks
Tim

[Dmitry at Pelican Parts]

Hi Tim - I'm attaching a link to DIY tech article from our site on this procedure. If you have any additional questions, feel free to post a Comment just below the article and one of our Porsche techs will get back to you with more details. Hope this helps and best of luck!

Porsche 911 Carrera Chain Tensioner Installation | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article

[Flat6pac]

You can still dial gauge your setting. Chain tension, when running is ever changing so I install the tensioner in place instead of taking the chain to a mechanical tension that will not be duplicated in the running motor..
You want the settings to be accurate but the average person uses the pulley for center line settings.
So easy to fudge the setting numbers you want.
Stompsky Racing produces a degree wheel for accurate crank relationship but I have never read about, on the Pelican, anyone using the product

Bruce

[Trackrash]

I always adjusted my cams with the stock tensioners. Just made sure there was no slack.
If you used a vice grip or mechanical tensioner, you would want to re-check your timing after you put the stock tensioners on anyway, I would think.

[jungspike]

thanks guys--yup Timing is still within spec. I think Wayne's caution is for if you got all rocker arms installed. Then, when you release tension, if a valve is open, the valve spring will have a tendency to rotate the the cam. Since I was at Z1 and only had one rocker installed, the cam didnt move.
Thanks, just trying to be very cautious.

[Norm01]

I've always clamped and believe I was following Wayne's instructions. I always thought this was because at higher rpm, the idler and tensioner will be at maximum extension and this is where it s most critical. Adjusting at static with the tensioner installed may not duplicate high rpm timing.

[yelcab1]

I have always done cam timing with the tensioners

[Norm01]

Double checked the Porsche factory manuals and they want you to pry the idler with a screwdriver, clamping would achieve same thing.