500HP how can you tell it is a real one vs. a 454 painted blue?
#6
#7
Charter Member
![](https://www.offshoreonly.com/forums/images/icons/charter_member_star.gif)
![Default](/forums/images/icons/icon1.gif)
There should be a large 8.2 cast in the side of the block. Also I am pretty sure all HP500's came with roller rockers on studs so If you have those that is a good start.
#8
Registered
![Default](/forums/images/icons/icon1.gif)
Look for the 8.2 stamped on the block, in the freeze plug area. Merc also made a HP450, that was a 454, but almost identical to a HP500 spec wise, other than the Cubic inch.
Even if it says 8.2 on the block, it will be a 502, but can have anything inside it as far as crank, rods, pistons, cam, etc. Tearing it down is really the only way to know anything for sure.
Even if it says 8.2 on the block, it will be a 502, but can have anything inside it as far as crank, rods, pistons, cam, etc. Tearing it down is really the only way to know anything for sure.
#10
Registered