Jana

Slightly dumb question, but it's not in the book that came with the engine. What should the torque be for spark plugs for an HP500?

TomZ

iTrader: (2)

They should be snug. I've never heard of anyone using a torque wrench to tighten plugs. Get them snug and them give them a 1/8th turn. That'll keep'em in there.

klmken

I think the Merc manual says 16ft-lbs...