Swap: Merc 470s for Merc 4.3Ls (Fit?)

[Jilly - 5]

I'm looking at a 25' open skiff that currently has a pair of Mercruiser 470 (4 cyl) power plants that I want to scrap. I had planned to re-power with a 6.2 L Mercruiser/Bravo 1 until I found the Mercruiser 4.3 L V-6 engines. The 6.2L requires glassing two transom holes and cutting a new center hole. I'm also told that this skiff was initially designed with twin 350s. Does anyone have any experience that will indicate whether the twin 4.3s will fit where the current 470s are? More specifically, I know the 4.3Ls will fit in the engine compartment volume, but will they lie adjacent such that their power shafts will align with the current 470 I/O transom cutouts? The primary attraction of the 4.3Ls is hopefully no transom work, a savings that makes up for the added price of twin engines over a single power plant. The 6.2 L will be Bravo1 and the 4.3Ls will be alphas.

 

[Don S]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

The transom cutouts are the same for the old 350's the 470's and the new V6's. If the holes were there for the 350's, then you are set for the V6's.

 

[Bondo]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

I'm also told that this skiff was initially designed with twin 350s. Does anyone have any experience that will indicate whether the twin 4.3s will fit where the current 470s are? More specifically, I know the 4.3Ls will fit in the engine compartment volume, but will they lie adjacent such that their power shafts will align with the current 470 I/O transom cutouts?

Well,....... If that 1st sentence is True ,..... Your Home Free,+ can do Anything you Please.........<br /><br />The 350s, 6.2l,+ the 4.3l are All SBCs.......<br />The 6 cylinder is Shorter, But the Width is the Same on All the engines...........

 

[Wstahl]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Am I reading this right? If I have a 1979 boat with twin mercruiser 470's I can upgrade to the V6 4.3 as a direct replacement as far as the hull is concerned? I know there would be electrical and other considerations but that would be easy compared to hull modifications. Just thinking of future upgrades!

 

[Jilly - 5]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Hello ThunderBird, this is Jilly-5. While I appreciate the other responses above, I'm keenly interested in your experiences with your 470s. Everyone has told me to get rid of them in my craft (poor design, magnetos, interior water pump, no factory warrantable parts, lousy idle, frequent stalling in close quarters, etc). How's your life been with the 470 powerplants?

 

[Don S]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Jilly, I guess what you should have done is ask the question you really wanted answers (or at least opinions) on.<br />Have you actually run your boat with the 470's in it? What kind of boat is it?<br />Froms the sounds of the boat, and it's previously being powered by a twin 350's, I would say your 470's are going to always be pushed to the limit. Because your boat is now way underpowered. Any engine that has to run that hard will have problems, regardless if it's a 470 or even the V6's you were thinking about.<br />I don't think Thunderbird is going to be of much help yet, he just got his boat also and is the process of removeing the Turbo's (another story) and getting the boat ready for the water.<br />If your engines are running now and have good compression, at least run the boat and engines for a while and draw your own conclussions on them. They are strong engines and lots of people that have them love em.

 

[Wstahl]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Don is right, new boat to me so can't be much help yet. I am keeping up on all the swap post so whenever the 470's die, I may want to upgrade. But you never know, the 470's may outlive the boat!

 

[Jilly - 5]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

I hear both of you. And my discussions and research suggest that 470s can easily outlive their owners. But at a great price in handling, idling, "external" parts repair, etc. I've had old cars that I loved and poured money into well beyond their useful life. But whether cars or boats or anything else, where I can live with less than outstanding performance, my wife requires perfect functioning of anything, or she won;t go near it. I've had cars (that i loved) that she wouldn't ride in. After one SeaTow last summer, it was "get rid of that thing" (21 Nova, 302 Merc). So I need perfect reliability and performance - reason I'm shying away from used 470s and going for new power with chip controlled motors, etc.

 

[Don S]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Back to my other question, <br /><br />What Kind/size of Boat is it?????<br /><br />Even if you go to the V6 engine packages you could be looking for trouble if the engines are too small for the boat. Any time you have an underpowered planing boat and have to run the engines under excess load at higher rpms to stay on plane or run just below planing speed, you are going to have reliability issues. Get the proper power get up on step and back off the throttles and you will use less fuel and the engines will be much happier.

 

[tommays]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

just my 2 cents<br /><br />i no that if you repower you will have a reliable boat BUT you will never get that money back if you want to sell the boat its only a good investment if you keep the boat a long time<br /><br />you dont own this boat yet i am wondering what is the total cost of this boat WITH the dual engine repower VS other boats that have a power package you are happy with<br /><br />tommays

 

[Jilly - 5]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Ok,OK! Here's the situation. My current Nova 21 has the deepest V hull from bow to stern that I've ever seen, better than Sea Craft and Bertram. It's a Don Aronov hull design (he invented surface piercing drives) while he was at Wellcraft, and he left only because Wellcraft didn't want to do Cigarette type boats. My boating is Block Island Sound where 5 - 6 foot seas easily develop by end of day. My 21' Nova just doesn't quite reach the next wave in such seas. But the hull is superb where I've gone airborne and re-entered the water without spilling a soda drink (lots of rpm jump!).<br /><br />I'm looking at a 1979 25' Wellcraft with an identical hull design (and cuddy) that has 470s. This hull will do 5-6 foot seas. At this time, I think I can get the 25' at such a price that ,with one 6.2 L, total cost won't exceed $25,000. With a pair of V-6s (EFI), total cost won't exceed $28,000. The V-6 scheme saves several thousand over the single 6.2L, for filling and cutting transom holes and stringer re-arrangement.<br /><br />Otherwise, I have not been impressed with other hull designs, cabin/cockpit layouts and power plants on new/used 25 'craft in the $25 - $30,000 range. Every boat seems to have some problem, is "too plastic looking", and/or, every seller wants to make back every dime he/she ever put into the boat (I've been nickled and dimed over even fenders and 50' line lengths!). I've looked at Bertram, Chris Craft, Regal, Winn, Regulator, etc.<br />The Wellcraft is my hull, has open cockpit, rich wood trim, and I love the prospect of engines never run before by anyone but me. I'm beginning to feel like my wife! And finally, 25' is max for my seasonal rack storage. <br /><br />Hope this helps explain the passion of my need for info. May even keep the easily trailered 21' for bay boating.

 

[Jilly - 5]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

One more thing. If this transaction comes to pass, I'll never go to another boat. Sooo, investment recovery is not an issue.

 

[tommays]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

well now i can see that you no what your getting you self into<br /><br /><br />good luck<br /><br />tommays

 

[Bondo]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Jilly - 5,........<br /><br />You have Superb Tastes.............. <br /><br />You also seem to have a Plan............<br /><br />Good Luck with your Conquest.........<br /><br />I searched for 4 years to find the Hull,.. I've been refitting for 2 years.....................

 

[mercrewser]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

I think Wellcraft mounted the 470s too close together to allow v engines to fit in their place. They offered the boat with twin V8s, as well as twin inline engines (6s and 4s), also single V8s. In all the pictures I've seen, the inline engines looked to be to close together to allow v8s to be put in their place. Also, your info on who designed the boat is inaccurate. Check my post on this site http://www.meridian-prime.com/novamarine/fhome.asp The Nova was based on a Donzi 7 meter hull. The designer, Allan Brown, chopped and channelled it into the Nova hull. <br />If your looking to sell the Nova 210, please let me know as I might be interested in it.

 

[Bondo]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

Isn't that what F_inscreenname's boat is ??

 

[mercrewser]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

He has a 19 ft Supernova. Also one of the original Novas. Wellcraft bought The 24 Nova Sprint, and Allmand bought the Supernova. That site above is run by effen. Wellcraft made all types of modifications to the Nova as the years went on. If it was me, (and I hate the 470), I would keep those engines in there, or pass up the boat. Expect close to 50mph top end with those engines. Around 60 with heavier cast iron V8s. The offered the 25' Nova with as little as a single MerCruiser 188hp 302 Ford, so 340hp of twin 4bangers will be just fine in the power department. Ultimate set up for economy and reliabilty was twin 250 I6 Mercs.

 

[rodbolt]

Re: Swap: Merc 470s for Merc 4.3Ls (Fit?)

contact mercs tech department. they have all the measurements and specs for engine width,stringer width and X dimensions. you will first need to determine if your current stringer placement is ok. then if the current transom cutouts are in the proper spot. then you may proceed.<br /> I have seen some hand made front engine mounts on V chevy motors. were interesting to say the least.