8.1 496 reliable build questions
 

This is a little off base for this forum but this looks like the forum with the most knowledge of these engines. I have a 25' Carolina classic offshore fishing boat. Weight is 12000 pounds loading for kill time offshore. It has the Volvo 8.1 with the standard water reversion thru the exhaust issues with engine failures around 500 hours. So I am getting ready to build another engine for this boat the donor is another Volvo 8.1 that has kicked the bucket from stuck valve hitting piston only 450 hours of run time on it. My plan is forged pistons to get rid of the problematic factory pistons, stainless valves and bronze guides in factory heads if possible, arp head bolts or studs, and then stainless marine exhaust with custom risers which he has made numerous sets of these for my style boat and it seems to be doing the trick to get away from water reversion in the exhaust. I am looking at staying at the 375hp level as it works well with my boat. I just want a reliable engine that is going to go 2000 hours. Where are places I can source these items or any thing else I would need. Thanks in advance I am located on the eastern shore of MD near ocean city.

you wont get 2000 hrs from a gas piston engine pushing 12K.....diesel maybe

Jegs, Summit racing are parts depots

You might want to downgrade the cam a little bit. You probably never use full throttle anyway. Of course, cams for that guy aren't easy to find, but you could-I believe-run a standard big block cam in it. I have a couple of gen 6 stock truck cams if you want one.

I'm running Scat H-beam rods and SRP forged pistons in my 496. Pretty sure the cam in the 375 HP version of that engine is close to the stock 8.1L truck engine cam. Not sure how you could get much more tame than what is already in there.

Well maybe not 2000 hours but more then 500. My last boat was similar in style and weight with a 454 and it had 2600 on the clicker never did anything but tune up and maintenance and risers. I am really just looking at sources for a parts for the build and any insight if I should do any different. The stainless Mari e exhaust is going to take care of the reversion 99% sure as others that have it installed on exact same engine and boat have had no issues. The stainless valves and bronze guides are just a precaution since I need to have the heads done anyway. Any idea where to source stainless valves or will the machine shop have to find them.

have the machine shop get them, and put Inconel exhaust valves in them

Now with pistons should I forge or shouldn't I. Also will they work with stock rods. Will the inconel valves resist corrosion also like stainless. Sorry for the questions I just don't want to trip over a dollar to pick up a penny. I just want a rugged build that will last. If you were in my shoes with this how would you do it.

Inconel IS stainless, only the toughest, most corrosion resistant and most importantly most heat resistant stainless there is. From what I have heard, GM used inconel exhaust valves in their big blocks from 96 or so on. Worth looking into. Forged pistons? If you are replacing pistons, definately. And I knew a guy with 2 454's in a sea ray sportfish with 2000 hrs. I had a 30 IMP with 2 330 hp 454's with 1000 on them and ran fine.

What material are factory valve guides, if the valves are inconel from the factory why are they rusting a sticking then kissing the piston. Just a question kinda thinking out loud

never mind