Advice on HP500 upgrade
 

I got my HP500's on the floor for winter refresh and was thinking about upgradeing the cam to a bigger one.I am torn between using my stock cam and going to a 1.8 rocker which would bring intake lift from .576 to .610 and exhaust from .598 to .633. or buy an aftermarket cam thats vertually the same. The money for cams about $275. each and rockers are about the same. any input or advice would be appreciated.

Call RMbuilder, AKA Bob Madera of Marine Kinetics, you should also replace your springs. Do a search you will find his info and many happy boaters.

With just 1.8 rockers your lift will change but not you duration, i would call bob like said above. I put a 741 crane in mine last year with some head work as well, and i would replace springs for sure on the 500hp.

Higher ratio rockers may require that you open up the pushrod hole in the heads. Higher ratio rockers can also be a little harder on valve spring. The higher ratio has a faster acceleration opening rate on the spring. Like the others said it only changes the duration a few degrees.

The crane 741 was what I had in mind for an upgrade. Do you like the performance gain? does it perform well with stock compresion. did you upgrade the springs from the stock 929's or just put in new ones?

the 741 is a great cam, i dont remember what is coil bind on the 929 springs but i think you will be getting close with that grind

WHat exahust do you have? Have you thought about reversion problems?

Go with a new cam instead of 1.8 rockers. The stock cam on HP500's was a 110 LS and was prone to reversion.

Im running 741 cams in my 500hps with stock gills with no reversion issues.

What kind of performance gain did you get out of the swap?