I have an old Python Vector with a big block and a bravo. I happen to have a zz502 sitting on a stand for a project that has been put on indefinite hold. I only use the boat to go a few miles to the local hangout and most of the run is speed limited. Can anyone tell me what I would have to do to run this in my boat? Thanks.

cam probably will not work well unless you have long runner headers or dry exhaust. Its known for causing reversion (sucking water back into cylinder)
Swap to a marine spec cam and brass freeze plugs and swap over all the marine accesories from your current engine and the correct flywheel for a 502.

Thanks for the info. Reversion was my main concerne. Anyone have a suggestion for a cam for this app. Due to the size and weight of the boat I don't need anything radical. I also have an Arizona s and m twin powerdyne set up I was thinking of puting on it just for shock and awe. Thanks again.

i would run it the way it is,,its not that radical of a cam with it being I.527 E .544 ur @ .050 I .224 E .234 lode seperation @ *110.. just get a good set of long tail pipes or header and call it a day..

if you opt to change it and want to use the factory lifters just make sur you dont go over .570 lift on the cam max!!

I ran a ZZ502/502 in my 23 Nova for 4 seasons trouble free, with the ZZ cam. The 1st season was with the stock Merc exhaust. If you keep the ZZ cam, and there is no reason you can not use it, set the idle to 700 rpm and be sure to crack the throttle a couple of times before shutting the engine off, after idling. That should (did for me) clear the exhaust manifolds of any possible water accumulation. I used the marine ignition, starter, circulating pump, alternator, etc. on the ZZ from my 7.4 that was removed from the Nova. Also, use a larger oil pan, and I would definately recommend a larger than stock oil cooler. My Nova ran 69-70 gps any day with the ZZ502. Your 24/7 will likely see mid 70's.

Thanks for all the input. I feel a lot better about it now. I have a few buddies that scared the s@#t out of me but they all have ultra high perf boats. The 502 is just collecting dust so I think I may just do it. If anyone else has any thoughts I would like to hear them. Again, thanks to those who took time to respond, H.

Also, you need to remove the 11lb oil bypass valve in the oil filter pad on the block. Plug it or use the 33lb one.
Do a search on ZZ502 in the Tech. Section, there is a lot of info.

Good catch Rookie. It's been a while and I forgot about the bypass valves in the filter pad.
Something else to consider, larger than the stock Merc oil lines. -10AN would be good.

Your both on the mark. Here's the short list:

1) Oil bypass valve change - GM part # available.
2) Oil pan change - marine BBC oil pan of your choice.
3) Large oil cooler is a must.
4) Merc BBC marine distributor or if you use the MSD distributor supplied with the ZZ502, then a rev limiter must be added.
5) Rocker arm change - roller rocker arms of your choice.
6) Stock cam is fine but exhaust manifold and tailpipe design and length may be a factor as also your care in use.
7) Carb needs change or mod - Install a Holley 950cfm 4150HP carb or at minimum change the vacuum secondaries to mechanical. (trust me on this one - the 950 is the carb to use)

Also, the ZZ502 crate motor block already has brass freeze plugs.

For further info, do a search on both OSO and Speedhump for specific change details.