Differences in early 90's 351 vs '95+ 351 engines |
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jo-e90
Gold Member Joined: March-16-2011 Location: Midwest Status: Offline Points: 659 |
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Posted: January-18-2012 at 3:23pm |
Is there that much difference in reliability.
I have been told that the EFI has more parts that can go wrong than a simple Carb and fuel pump. Which motor would be easier to work on for a shade tree mechanic? In other words - carb vs EFI pros/cons I dont care about great pulling power, holeshot, and good top end. |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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The simplest for a shade tree mechanic would be the old style with a distributor, mechanical fuel pump and carb.
The latest versions, the GT-40 with 310 is considered desirable, and as far as I know, has very good reliability. These actually do have a distributor, but have many other sensors as well. The ones that are having trouble now, is the era with the "Pro-tec" ignition. These don't have a distributor and use coil packs. When these fail, the only thing you can do is retrofit them with a traditional distributor. Of the Protecs, some have carbs, and some have throttle body injection. If the throttle body injection type fail, not only do you have to buy the distributor retrofit kit, you have to buy a carb and fuel pump as well. |
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jo-e90
Gold Member Joined: March-16-2011 Location: Midwest Status: Offline Points: 659 |
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What model year Pro Boss motors ran the Pro-Tec ignition?
Also what model year boats had the TBI ignition? |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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I think anywhere from 91 to 95 or so, Protec is a possibility. TBI may have been an option I'm not sure if it can be done on strict year to year basis though. Mine is a 93 and never had Protec.
The best thing you can do is see a picture of the engine. ski dim home page has engine and distributor identification galleries, although, no pictures of a protec equipped boat. This page show as Protec equipped Chevy Big blog. The Ford Protec gear would look similar, with the little coil packs and stuff. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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From 91-94, Protec was pretty much standard fare... though technically an option, at least for 93-94. The GT40 (multiport) debuted in '95, and carried the Ford EFI torch from 96 on. The TBI was only offered '94-95.
Many boats out there are still running fine with the original Protec ignition, though I wouldnt claim it to be as reliable as a conventional distributor. Brian was right on all accounts above. A carb will be a little easier to maintain yourself if youre half way handy- fewer parts to fail and easier to troubleshoot. The GT40 is widely considered one of the great marine engines, and is very reliable as well. EFI will start better cold and probably be a little more fuel efficient. None of the engine options would really scare me away from an otherwise "perfect" boat. GT40 boats will command a little more $$. Id try and negotiate a lower price for a Pro-tec equipped boat on the basis of having to replace it "someday". |
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jo-e90
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Does this boat have the Proboss (carb), Proski (TBI) or GT40 (MPI)?
http://www.marinemaxminnesota.com/Page.aspx/diid/5960244/list/InventoryList/pageId/34597/view/Details/1995-Nautique-SPORT-NAUTIQUE.aspx |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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TBI. The HO TBI's were labeled "Pro Boss", just like the carb'd versions. (I think even the GT40's got ProBoss labels... though theyre not generally referred to as such.) Only the non-HO TBI's were called ProSkis. |
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jo-e90
Gold Member Joined: March-16-2011 Location: Midwest Status: Offline Points: 659 |
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thanks
I scrolled down to the bottom of this link for a visual comparison which helps. http://www.planetnautique.com/vb3/showthread.php?6772-PCM-351 |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Obviously those pictures and descriptions were posted by someone who knows what theyre talking about.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Of course, some of the boats that would have had Protec, already have the retrofit. One way to tell if the Protec is still in place is by the hockey puck looking thing where the distributor would normally be. I couldn't really tell from the pics on the boat you were looking at.
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storm34
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Only because he as one of each |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Ha, it sure feels like it sometimes!
(For the record, I dont have any of the above... at least I dont think I do!) |
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mdvalant
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I just wanna follow this thread. Nothing confuses me more than how these motors differ. Does this motor not have a carb? (forgive the stupidity but all this time I may have been lost) |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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No- the "Electronic Fuel Injection" decal on the shroud is a good clue. That motor uses TBI EFI. TBI = Throttle Body Injected. Basically a fancy electronic fuel metering system that takes the place of a carb. Its a bit "cruder" than MPEFI (Multiport EFI), which is what PCM went to, starting with the GT40. In that system, the intake is dry (no gas) and each cylinder has its own dedicated injector. |
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mdvalant
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Thanks Tim, That's kinda what I thought but I was having doubting myself lately due to the fact that it sure as heck looks like there's a carb under that plastic! Good stuff. Thanks!
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TX Foilhead
Grand Poobah Joined: February-01-2009 Location: Kingsland TX Status: Offline Points: 2076 |
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Having had a ProTec motor, I wouldn't be concerned. I got 900 hrs out of mine and another 50 or so once it started going downhill. Changing it out is really simple, with all of the documentation here it shouldn't take much more than an afternoon. Mine took longer, but it was my own fault wiring the dizzy backwards. The extra hp from the Pro Boss is worthwhile. I haven't dealt with a GT40 in an inboard, but have used an I/O with that motor and it has been problem free for 15 years and counting.
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