Reinstalling MPI back onto a carbed 496 in a 1997 Baja Islander
 

So I picked up this boat that the previous owner bought with a cracked block 454 MPI HO, and he had replaced it with a 496 but opted to just put a carb and distributor on it rather than mess with the fuel injection. I hate carbs and love fuel injection (at the moment anyways) and am in the process of reinstalling the fuel injection. I have only played with carbed small boats before so there is a lot of mystery here.

If anyone has any pictures of what the engine bay should look like that would be greatly appreciated.

How do I set the timing on the electronic distributor? I took the cap off of the electric distributor and oriented the rotor to exactly where I pulled the old one out, but it looks like the timing still needs to be set, yes?

Where is the best source for a shop manual? I've done a search but haven't found anything that looks legit.

Thanks in advance.

There is no way anyone is going to be able to accurately tune/recalibrate the ECM except in the boat or on a dyno. You better figure out who is going to do that first.
You can order Merc manuals at www.mercruiserparts.com

Just curious is this a 496 stroker motor or the 8.1 496 ?

Stroker 496 on a gen xi 454 block.

Gen VI? Or is yours one louder and goes to "11"!! Lol! JK.

What's the HP of the 496 ?

Supposedly 500+. It came off of ebay as more of a truck motor with a lot of Pro-Comp parts which I guess Aren't that great.

This is the motor. http://www.ebay.com/itm/230924067902

It may not be the greatest, but hopefully it will get through a season or two. I tried so suss out whether or not it's a good idea to put the injection back on here, but I couldn't get any conclusive straight answers, so I talked with the engine builder and naturally he said there'd be no problem with it.

I've built some small block chevy's before and a lot of high performance motorcycle engines, but this powerboat thing is all new and very foreign to me so I expect quite a learning curve ahead of me.

It depends how much you like to tinker, nothing written in stone here but marine motors including FI are generally setup with very rich afr's there's very little precise fuel metering going on that is unless one welds OS sensors into the exhaust system..and even with that they generally lean out in the midrange cruising speed say 3000 to 4000 and enrich it back up from there. One can play a bit more with timing curve's and if you have a hot cam in the engine one can tame it down a bit by advancing the timing @ idle to soften it up a bit.....or run the timing on the ragged edge for the last 10 hp...for a experienced programer thats half the fun.

Boater's become very opinionated when it turn's to modification's and a lot of money can flow, but a well built engine with a properly tuned carb will cost far less and preform very well...i doubt there would be any big gain's aside from low speed cruising economy.

Not picking on your motor, the heads look a little rough around the valve seats, the 108 ls cam probably isn't all that good for marine or EFI. I would think the fuel injection would be fine if you know someone that can remap it for your application. First check the vacuum at idle, if it's to low the ecm might think it's under load and run rich. Second check the fuel injectors and find out if they are big enough to handle your new HP.

ok, hate to be the one to piss on your wheaties, but most all that pro comp stuff sold on ebay is absolute garbage, second trying to get the merc EFI to work with that is going to require good tuning ability...you might want to talk to eddie young @ youngs marine, on here, but I can tell you as soon as that thing is started...the pin has been removed...