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Merc 454 carb to 496 HO?

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Old 08-08-2011, 08:20 AM
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Originally Posted by NightHawk
I made that engine change. The exhaust was a little tricky since the thru-hull dimension was different but it was worth it. The 496 added 100 HP to my boat and it's a much sweeter engine because of the EFI. Carbs are yesterday's technology.

You should consider picking up a mercury SmartCraft guage to go with that engine. It's easy to install, inexpensive and very useful.
Enjoy the bliss. Wait until it won't start one day and you spend a month tracking down what is wrong rather than five minutes with a non-EFI motor. Marine EFI is a long way from perfected yet.
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Old 08-08-2011, 08:39 AM
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Originally Posted by Pismo10
Enjoy the bliss. Wait until it won't start one day and you spend a month tracking down what is wrong rather than five minutes with a non-EFI motor. Marine EFI is a long way from perfected yet.
I couldn't agree more, I can't wait to have a carb again .
2nd 496 in my boat and I can't stand them. Big inch carb motor next (one day)
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Old 08-08-2011, 09:38 AM
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I saw that 496/whipple on here in the classifieds. If you dont mind me asking what did you finally pick it up for?


Carbs are easier for folks that grew up with them, im a transmission tech that grew up in the efi era so its easy for me and the carb looks foreign to me lol. We already have a mercruiser scanner for my pops fastech so im not so worried about diagnosing issues.
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Old 08-08-2011, 09:48 AM
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Originally Posted by Pismo10
Keep the carb....
Im willing to listen to all opinions and different routes to take but I have the 330hp and want to be in that 400-430 range that the 496ho puts out. How can i make it as effecient as an efi and put that out without going crazy with cams heads etc?
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Old 08-08-2011, 01:05 PM
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Originally Posted by I.D.C.E.
Im willing to listen to all opinions and different routes to take but I have the 330hp and want to be in that 400-430 range that the 496ho puts out. How can i make it as effecient as an efi and put that out without going crazy with cams heads etc?
Nothing wrong with the 496 engine, don't let guys scare you away. Thousands and thousands of those engines out there making reliable power every day. IMO that engine gets a bad rap sometimes because it is the most current engine in today's internet forum world. 454s and 502's had their problems as well, just back then you heard about them local on the dock, not from the whole conuntry on the internet. It has the illusion of being a bigger problem.


For you to convert your 330hp into something with 425+ horse would take some work. And to tear it down to base, get new heads, new accessories to keep it cool, new intake, new carb, new exhaust, and make that whole package work reliably......yada yada yada. Or, just drop in a proven merc engine with 425 hp?

Pull the 330hp, set it to the side, drop in your compolete 496, run it. When you sell the boat convert back and sell the 496 for near what you paid for it.
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Old 08-08-2011, 03:28 PM
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What are good condition 454s going for these days. I saw one in the classifieds that was going for a nice chunk of change.
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Old 10-03-2011, 08:01 PM
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Anyone have a 496HO that they are selling even if the engine needs to be rebuilt.... i'm in the market to get this project rolling.
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Old 10-04-2011, 02:40 AM
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I have a 2400 VIP Vindicator that came with a 454 mpi, 310hp I think . Lasted 7 years. water leak in exhaust manifold killed it. Had it rebuilt. Ran 3 times and spun a bearing. Pulled it out and replaced with a low hour 496 HO 425 HP. Picked up 9 mph and thats with a 4 blade prop. Had a 3 blade before. Prob 2 more mph in it with a 3 blade. I do like the 4 blade for cruising.. I can stay on plane at around 18mph. Was like 24 before. Best thing is it was plug and play. Only thing I changed was the prop. The first time you you crank over the 496 and it fires up after only turning over a couple times, you will be sold on the efi. depending on the year 496 you buy, some can run a little rich. Its good idea to change the plugs every 2 -3 years or so due to this. Go ahead and change them before you drop the engine in. Also change out the water pump before installing in the boat. One big plus for you is your fuel consumption will be cut by 30-40 %.

Chris
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Old 10-04-2011, 05:52 AM
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Thanks for the info, thats exactly what im hoping for. Do you have any pics of the swap? Where did you find the 496?
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Old 10-04-2011, 10:51 AM
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The 496 is done, nothing interchanges with it, that's why many people don't like it.

Is this for your PC? IMHO you're wasting a lot of resources messing with a perfectly good running engine. You'll put in a lot of effort to get 2-3mph.
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