Not to burst anyones bubble but if I am reading what you are saying correctly you have a 7.4L motor. Just to for worn you that you may not want to spin that motor over 4900rpm's max because if you have this motor you have a cast crankshaft. It will not be a matter of if you will break it but, more so when you will break it.

I do know that it's a cast crank, and that the rods are perhaps not the best ones. Isn't it the rod bolts that break first, if you overrev the engine?

I still believe that it will easily stay together for around 420 hp. It is also going to be mounted in a rather light weighted boat - around 2200lb.

There has been alot of previous threads on cast cranks with many opinions. It seems the majority feel its fine up to 500hp. Do a search and see what you find.

Just as a price comparison, I have fresh 454ci with dyno time only. (Originally Merc HP425) Made 430hp on dyno. It includes all accesories, cooloers, plumbing, gil manifolds/ risers and transmission for $5000. This is a ready to drop in deal. When comparing that to a $3000 dollor upgrade that will be on a stock used bottom end, it seems there are better routes. My. 02$

I see that your location may not be great for performance marine v-8's

Just wondering (if you are talking about me) - why is my location not great for performance marine V8's?!

It seems that many of the boaters here on OSO has started out with 330's. Has there been any particular problems with hotting up them, that I should keep in mind?

The L-29 Vortech seems to be a fine pair of heads, or what do you guys say?

[QUOTE=tomas_wallin]It seems that many of the boaters here on OSO has started out with 330's. Has there been any particular problems with hotting up them, that I should keep in mind?

QUOTE]

Rod bolts, get the best ARP's, Blueprint bottom end (correct machining and balancing). Get the best components for the valve train, inconel exhaust valves, severe duty intakes, one piece 3/8" pushrods, stainless steel roller rockers, arp rocker studss, etc. Stay conservative on your cam choice. Set the quench around .040 and keep the compression close to 9-1 and off you go. Keep the oil temp under 250 at wot, may require bigger oil cooler and better oil plumbing. Have fun and good luck.

Yepp, I think I have understood the importance of quench so it is going to be around .040!

Is there some perticular oil that I should use?

Thanks!

do a search on "dyno's 330's on roids"I built them a couple years ago, new heads and exhaust bumped the compression to 9.5/1 rockers and some other add ons they made 505 hp at 5600 rpm.

I have already read the 330 on riods among many other threads. Most of them contains really interesting stuff!

I'm gonna read some more tonight, then I probably have some more Q's