kinda noob question but 1st engine with a serpentine belt and no manual. How do you measure the correct tension on a serpentine belt on the 496HO? Friend said you should be able to twist it 90 degrees no more? I put a new belt on and had to adust the alternator bolt all the way in. Is there another adjusting bolt?

Thanx!

you sure you have the right belt? I know on the 500's theres a idler pully that ajust the tension

yep

Merc maintenance manual says if by hand at the longest section between two pulleys (basically the top)

"...belt deflection by applying moderate downward pressure on belt. Proper deflection is approximately 1/4 inch (6mm).

Basically, if you've ever done one on a car you simply do the same thing.

that is the only adjuster bolt and what you have is normal