I have a 2002, 47' Wellcraft Excalibur with 496's and B3s. I am not happy with these engines, nor the drives. I need to get these motors up to spec or a swap is being considered. I researched a lot of post on this forum, but there are so many to choose from!

According to Riveria(who built these for Wellcraft), the 47' with twin 496/425/B3 should run 49-51(light), with a 4700-4900 rpm indicated. Press releases for the same boat claimed 54mph, but I think that might be very optimistic.

I have two different things to ask:
First ask:
I have spent a lot of time with the only folks that seem to have any love for the 496, and that is Larry at Raylar Engineering(I cant post URLs yet). Great guy to talk too, and I am considering the bolt on options they offer, namely the intake mods, cam, and roller rockers. But most research I find on this forum seems to lean towards the fragile nature of these motors and one should not expect to much from them if you start trying to build power from them. But mine seem to be under performing and I need to find someone who can get these motors running correctly. When I first bought this boat @600hours, I was able to see 45-48 MPH at 4500 rpm. This was reasonable, but now they cant get past 3800rpm, and a cant get past 32-34mph. I have only put on 40hours. I have had them scanned twice hoping this was the "guardian mode" PCM 555 issue, but this seems to not be the case according to Highport marina(but I dont trust these guys). I have replaced filters, oil, and checked fuel pressures. Changed plus, checked the coils and wires. All seem correct. I need to find someone local to North Texas that can give me better diagnostics on why I have lost so much. Any thoughts? I'm on Texoma at Highport, and this boat cannot be trailer-ed as it is very expensive to do so. And yes, the bottom is clean, and the drives are clean(pulled out and had a full power spay and burnish on the bottom paint).

So my second ask is this: If I swap to a more traditional Big Block configuration such as a 454, 502, etc. What components will I be able to use from the 496(425 mag)? If I can just swap in a dressed block, and bolt all the accessories and headers back on, then that is good news. Also, if I keep the B3's and go to a higher performing engine, what are the upper limits of these drives? I dont wish to put high RPM motors, but would like to get close to 500-550hp and 550-600 tq and keep it at or below 4800rpm. No power adders either. I had twin 502mags in my previous 31' boat and they were fabulous! I beat them up every time I hit the water, and would love to have such durability and drive-ability again. I would not be using the Merc computers, but the Fast E-Z marine with "wet" O2 for induction, and a compatible spark controller/dist.

Thanks to all in advance!
-Jeff

For mechanic see BUP

As for the B3, it will handle all the speed you will get, but will probably need to go to a Bravo X or XR upper. My 27PC weight is more then 10K and I have single engine at 530 HP 502, with XR upper and B3 lower. Your boat weight is over 17K dry and maybe 20K loaded, so 2 B3's should not be an issue IMO

BUP, (I would not look any further!)

So does this mean you are they guy I need? Let me know next steps. And Thanks!

-j

I am not BUP but he is John owner of Boats Unlimited out of5709 Airport Fwy
Fort Worth, TX 76117 Wedgwood 817-658-7721

I owned a 47 Excalibur. bought it new in 2002. Ran it stock, best speed was 48-49mph on GPS. The second year i owned the boat i put a Whipple kit on it and she ran 56mph. Then changed to Stainless Marine GEN III exhaust and it ran 59mph on GPS. ..Then i was tired of re building the B3 drives every 60-80 hrs. Gears would wear out prematurely due to load of the boat. Then i had a great idea to put Arnesons 7M on the boat. So i did that. I figured why not build bigger engines since the drives could handle more. So I built a pair of 582cui w/ 4.0 Whipples and the boat ran almost 80. So in thinking back if i was you, id find a pair of 525efi motors and convert to 540cui and call it a day. Those 496 motors w 640 hours on them are tired and done

Very cool! I would love to do all that myself too. But, maybe I need to stair step into that drive setup. SOunds like the 496s held up for you as new, but as you said, mine are tired. For now, I just need to get what I have running better so I can save my pennies for something closer to what you had......

I may have seen you boat, as when I was looking for mine, I found a something very much like you describe. It was a bit out of my price range, and the wife was not happy about climbing over props to get into the boat. I think there was a cool YouTUbe too.

wow. 80mph in one of these would be so cool! It is a good goal to have for sure! Thanks! -jeff

Thank you. I sold the boat. Its out in Lake Cumberland now blowing rooster tails. I wouldn't put any extra money into those 496's. Just get them running better as is. Sounds like you might have a fuel problem. There is an anti siphon valve at the top of the fuel tank connected to the ball valve. Mine were clogged and i just removed them. Check fuel filters and Fuel injectors. Send the injectors out to be cleaned. Check and make sure your drives are trimming in and out properly. Does your exhaust exit through the side of the boat through an integrated muffler built into the boat or is it through the drive? could be exhaust restriction

THANKS GUYS for putting MY NAME out there for the this.

Too Funny I use to be a Challenger Offshore powerboat dealer as well among other new boat brands. I see Challenger listed as boat he use to own.

My contact info is posted in this thread - I am sure I could figure out any of the issues at hand here with your boat / engines and so forth..

The week worth of heavy rain really stinks as well in the area.

With that size boat and weight I do not recommended HOT RODDING the stock 496s. I have in the past but really not that much to pick from for part upgrades. Dart and Raylar thats it.