I have twin 318's in my 27', and this is my take on them. The 318 as they are installed in Uniflite's is a really good marine conversion. And, as you stated, they offer plenty of power without having to push them very hard for these boats in the 27-28' range.
The 350 conversion is also a good engine, particularly if you get a Crusader. With the Vortec heads and electronic ignition and fuel injection, they would be much more powerful and efficient than the old 318, no doubt. A fresh, new pair of those would be a dream, but..... You already listed the costs for the new 350"s, and just the engines alone are substantial. Now you have to update everything else to match: transmissions, wiring harnesses, gauges, fuel systems, shafts and props, etc. This all adds up, not to mention the labor involved with doing it correctly. It's gonna add up to a really big bill. And a cost that, I hate to say it, you'll never recover. Not on resale value; not on improved efficiency. There are still plenty of parts available for the 318's. And finding someone who could do a first-class rebuild on them shouldn't be too hard either. Have them do you a top-notch job. Since they're the same engines, they'll just slide in and out, everything will just bolt right back up. Put the electronic ignition conversion's in and maybe replace those Carter carb's with a slightly smaller set of Holley's. Keep an eye on the cooling system and keep oil in them and they'll run forever. I know of guy's with literally 3-4000 hours on their 318's. Mine have 1500 hours on them and have never been cracked open, except to change the exhaust manifolds. Do I run them hard? Hell, no--they're forty years old, and I'm not going to ask for trouble!! But with the install that you and I've got, you don't NEED to run them hard. I can cruise at 27-2800 and get 18-19 knots, and, if I'm feeling sporty, I kick her up to 31-3200 and make 22. Wide open is about 4200 and I'm too scared to look at the speed!! A pair on new 350EFI's are going to get you close to 300HP a piece (or more). You just don't need all that power; you'll be paying for capacity you really won't use. Will they be more fuel efficient? Yes, somewhat, but you still need to feed 350 cubes, so it maybe 10-15% better at best. For the difference between the cost of the 318 rebuilds and the cost of new 350's, fully installed, you can buy a WHOLE LOTTA gas!!! Only you would know how much you use your boat. For me, it's a no- brainer. Break-ever payback would be somewhere beyond 40 years. And by then, I'm sure I'll have much more pressing concerns to worry about-- or maybe not a problem in the world!! Good Luck!! MAH On Dec 8 2010, 12:15 pm, john hamilton <[email protected]> wrote: > Most gas inboards are GM based. That doesn't mean they're all the same. > Check this out.www.yachtsurvey.com\GasEngines.htm > > John > > --- On Wed, 12/8/10, John Strong <[email protected]> wrote: > > From: John Strong <[email protected]> > Subject: Re: [UnifliteWorld] Re: 318's vs 350's > To: [email protected] > Date: Wednesday, December 8, 2010, 6:30 AM > > Crusader is a marine engine company that uses GM cores. Marine Power and > Mercruiser use GM too. I'm assuming you have Velvet Drive transmissions - > they're simple and tough, and usually worth keeping. I've got a Salty Dog > with carbureted 350's and they will push the boat at 22 knots at around > 3000. Don't know the fuel burn. Don't want to know! > > The new engines will come with new cooling systems, so be sure you get them > with fresh-water-cooled exhaust manifolds. The only raw water will be in the > heat exchangers and the exhaust elbows. You'll never need to replace the > manifolds. Bigger cooling systems may mean bigger thru-hulls, seacocks, > strainers, etc. Replace all the metal in the exhaust system with fiberglass, > and replace all the hose too. > > EFI will mean modifying the fuel tanks with return line fittings. It may be > time for new fuel tanks anyway. You can get new tanks from Uniflite's > original tank maker, Coastline Mfg. - they still have all the drawings. As a > portion of a repower, not all that expensive. > > http://coastline-tanks.com/http://www.mercurymarine.com/engines/inboards/http://www.marinepowerusa.com/replacement.php > > Your Sport Sedan is *absolutely* worth repowering. What a great boat! > Replacing it with something new of equivalent quality would probably cost > $200K. You can do the repower for a tenth of that. Go for it! > > John Strong > [email protected] > > On Wed, Dec 8, 2010 at 4:04 AM, Suzy-Q <[email protected]> wrote: > > Thanx Kenny, > > The quote was for new carburated 350's. I don't know if they were > "Crusaders" or not. Is the "Cursader" an upgraded 350? > > On Dec 6, 11:28 pm, Keith Washburn <[email protected]> wrote: > > > > > That's not a bad price if your talking about the crusader efi 350s I > > repowered my 32ss with the Crusader 8.1 efi I had 454s the efis are way > > more efficient and trouble free. My old engines gave me 13 to 15 knots sob > > at about 28 gph the new engines give me about 20 to 22 knots at the same > > fuel burn . > > > Sent from my iPad > > > On Dec 5, 2010, at 10:01 AM, Suzy-Q <[email protected]> wrote: > > > > I have a 28' Sports Sedan with twin 318's. Engines were most likely > > > overhauled in mid-90's. The boat sat for many years, ran rough for a > > > while and it was not until late this summer that I got the engines > > > working well and could cruise at 2800-3000 rpm. (19 - 22 mph speedver > > > land at that rpm). After a few hours of cruising the starboard engine > > > started smoking when I returned from a fishing trip. The compression > > > was 120psi+ for all cylinders except #4 which was low at 60 psi. I > > > pulled the heads and found that the head gasket had failed. No water > > > in the oil just oil in cylinder #4. > > > > I was planning on replacing the exhaust manifolds/elbows and risers on > > > both engines this winter which is not going to be cheap. Now I'm > > > faced with the decision to repair/replace the stbd engine as well. My > > > mechanic recommends repowering with new 350's and reusing the > > > transmissions (approx $22k). To install a rebuilt 318 would cost $8k - > > > $9k, including exhaust parts. > > > > Anyone with experience in this area? Will the 350's be more > > > economical, provide more speed or be easier to maintain over the life > > > of the boat. I'm trying to talk myself into spending the money to > > > repower the boat and enjoy expensive but some hassle free fishing. > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "UnifliteWorld" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]. > > > For more options, visit this group > > > athttp://groups.google.com/group/unifliteworld?hl=en.-Hide quoted text - > > > - Show quoted text - > > -- > You received this message because you are subscribed to the Google Groups > "UnifliteWorld" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group > athttp://groups.google.com/group/unifliteworld?hl=en. > > #yiv861390354 #yiv861390354avg_ls_inline_popup{padding:0px > 0px;margin-left:0px;margin-top:0px;overflow:hidden;word-wrap:break-word;color:black;font-size:10px;text-align:left;line-height:130%;} > > -- > You received this message because you are subscribed to the Google Groups > "UnifliteWorld" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group > athttp://groups.google.com/group/unifliteworld?hl=en. -- You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. 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