Hi, Ken. I've toyed with the idea of what to do with my 440 Chryslers in my 36 SS whenever they get tired (they're fine now), and waver back and forth between rebuild vs. replace. If I replace them, it will almost certainly be with 6-71 Detroits.
But David Pascoe's opinions on the gas vs. diesel issue are compelling. I can rebuild the MoPars for around $10k for both, doing some upgrades (replacing intake manifolds and maybe changing to marine- certified throttle-body fuel injection which should improve the mileage somewhat). A pair of 6-71's will cost around $25k to do proper rebuilds, and what with the purchase price of a couple of rebuildable engines, the rebuilds, new transmissions, shafts, reworking the shaft logs, props, labor and so forth, I figure I'm probably into it about $50k. A pair of new Yanmars with transmissions will set me back about $80k all in, to make a boat that I might have sold for $50k two years ago, and less now. The difference between the Yanmars (or any 4-stroke diesel) and the Detroits is that the 4-strokes will get much better economy at trawler speeds. Being two-strokes, Detroits (like the 3-53's you're looking at) have a very narrow efficent power band, just a few hundred RPM below wide open throttle. At idle or just off idle, they're using almost as much fuel as at max sustained RPM. The Yanmars will get better economy than the Detroits, which in turn will get better mileage than the Chryslers. No getting around it. The Chryslers, like the 4-stroke diesels, use less fuel at lower speeds. So if I'm really serious about saving money, I'll run at about 7 knots and 1,200 or 1,300 RPM. Lightly loaded like that, the Chryslers should last for a very long time, and I've got a huge power reserve to haul hull if I get caught in a blow. I would think that a pair of 318's would give you the same option, together with the ability to do much of the routine maintenance yourself. So rebuilding my engines saves me a minimum of $40k. If the difference in price between a gas boat and a diesel boat in the same condition is $20k, then that's $20k I can blow on fuel and still break even. At 20 knots, my boat burns around 20 GPH. I don't think the most efficient diesels would be less than 10 GPH at 20 knots, and the Detroits would be more. But using that number, and assuming that gas and diesel are the same price at the fuel dock (and lately, diesel has been selling for more than gas), and further assuming a fuel price of $2.50 a gallon, I figure that the $1.25 per nautical mile I save means I have to travel 25,000 miles before I break even on the fuel savings from diesel. If I travel 500 miles a year (and I've never done it yet), I should break even in 2059, just shy of my 100th birthday. Like Mark Twain said, there are lies, damned lies and statistics. But on older Uniflites, there's just no way to justify the cost of repowering with diesels versus doing a first-quality rebuild on good marine gas engines. On the subject of marine gas engines, I'm going to stake out a position. This is an opinion based on a lot of talk with boat mechanics, owners and various marina hangers-on, but it's still just my opinion, which is that the older Chryslers are about the best gas marine engines out there. The new Crusaders with electronic fuel injection and electronic engine management are very impressive, but they're based on automotive blocks (usually Chevrolet). The thing is, Chrysler was the *only* major marine engine manufacturer that had its own, in-house, marine division. The marine division had input into Chrysler's engine design, and also had control over the manufacture of the marine engines. So even though they share dimensions with car engines, the marine engines were not just marinized (marinated?) car engines. All the other marine engine manufacturers (Crusader, Pleasurecraft, Waukesha, Graymarine, etc.) took potluck from Ford and GM (and even AMC - I've got a friend with an old Century that had a Graymarine V-8 and it took him forever to figure out it was based on the old Rambler 327). One exception - Mercury Marine did develop a marine engine independent of car makers. I believe it was the 140 hp four-banger, but the rest of their engines are based on automotive blocks. So it would seem to me that doing a really first-quality rebuild, together with sensible upgrades, of your 318s would be the best balance between reliability, longevity and cost. Of course, my opinion is worth what you pay for it . . . --~--~---------~--~----~------------~-------~--~----~ 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 at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
