I am in the middle of rebuilding my hp500. when I tore it apart it had damage to the heads from what is believed to be reversion. I have another thread up regarding this issue. I have put together a little slide show with the cam specs(from cam dr machine) from the cam that was removed, the risers, and the headers. it has a 110lsa but seems to be a little different from the stock hp500 cam. I am hoping this cam is the reversion issue possibly combined with low idle. can anyone identify this cam? is it a car cam or marine cam?? any info would be great. http://www.youtube.com/watch?v=YWI6K...ature=youtu.be

no ideas?

It looks almost dead on with the specs of a carbed HP500cam.

close, but not exact. the cam dr report was 2 full pages with alllll kinds of specs. I wonder what makes a cam a "marine cam". most people only think of lift and duration. this report had opening and closing times at different lifts and all kinds of specs that only cam professionals could understand.

Some auto cams work fine in a marine engines. The Lobe sep and overlap are what you need to look at for a marine cam with wet exhaust.
Even the sock Merc HP carb cam reverted some water idle and Merc modified the risers.

in the slideshow with the cam specs I have pictures of my exhaust. does anyone know if the risers pictured are what are considered the "tall" risers that merc released to fix the reversion?

Yes they are the taller version.

Looks like they did the test using a 1.72 ratio rocker. The lobe lift combined with 1.7 ratio is about dead nuts with a HP500 cam.

To sum it up, I think there are much better cam choices out there for your engines from both performance, and reversion standpoints. Bob Madera can set you up with great camshaft and valvetrain combo.