Any Porsche 928 experts out there? <Timing belt>

[Toxicant]

Hello all,

I'm doing a timing belt change on an '87 928S4 and I need to set the tension. I have the service manual and it calls for a setting of 5.0-5.3 which is great but its reading you'd get from the Porsche special tool which is unavailable to me.

I've seen all kinds of aftermarket belt tensioning tools on the internet so its obvious you don't have to have the Porsche special tool to do the job, so here is my question.

I have a Borroughs belt tension gage which is a far better tool then some of the ones I've seen on the internet all I need to know is what would be the proper ft lbs.

I'm guessing that it should be around 75-79 but on an interference engine guessing is not wise.

Anyone have any idea?

Thanks in advance!

Ron