Engine conversion question |
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Brad_K
Groupie Joined: April-18-2005 Location: United Kingdom Status: Offline Points: 67 |
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Posted: May-23-2005 at 3:55pm |
Hi all, once again I need some advice. I have got a 1980 Barefoot Nautique which has the 7.4 pleasure craft V8 which I believe is called the 454. This is the original engine that came in the boat and it is 100% perfect with no problems. The problem I have is that the Fuel prices in the UK are huge and so am burning around £80 per 4.5hour session which is about $136. I have spoken to a main agent about an LPG conversion which I am going to do but he has also offered me an engine conversion free of charge to the smaller Ford Windsor based unit which I think is a 5.7 V8 with a years warranty. This engine is a 1998 and so much newer but my question is will this engine burn much less fuel to make it worthwhile, and will the drop in performance effect me at all? I mainly wakeboard if that makes any difference.
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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I appeciate your predicament but honestly, wouldn't you come out better to trade boats and find one with a smaller engine?
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Happy owner of a '66 and a '68 Mustang
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Brad_K
Groupie Joined: April-18-2005 Location: United Kingdom Status: Offline Points: 67 |
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I am not sure, over here in the uk older ski boats are few and far between and to find one in good condition is even harder, If i go for this deal i still keep my hull which is in good condition and i get a more economical engine. I guess a better question to ask is how does the Ford Windsoe engine copy with running lots of ballast?
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climbhigh
Newbie Joined: May-18-2005 Location: United States Status: Offline Points: 17 |
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Brad,
Keep the hotrod motor, sell the kids and wife if you got to. |
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S. A. Meade
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cshire
Newbie Joined: July-02-2004 Status: Offline Points: 21 |
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Small block Ford and Chevy are the standard, base motor in current Nautiques as well as most other inboard ski and wakeboard boats.
The big block 454 was offered in the Barefoot Nautique due to the higher top speeds of barefooters and the drag from barefoot deepwater starts. You should be fine with a Ford 351 engine. If the engine is fuel injected you will see better economy without sacrificing too much power. If engine is carb you will still see some savings. Make sure you check rotation on new engine before starting any conversion. An '80 nautique would have been reverse (clockwise viewed from rear) rotation with the standard Ford engine, I'm not sure if the Chevy 454 was the same. It may be marked on your bellhousing or it is easy enough to watch the motor spin. Changing rotation would involve modifications to the transmission and a change in prop. Of course you may need to re-prop anyway with your conversion to the smaller motor - I don't know what prop came with the 454. Curious as to why someone would offer to convert to 351 for you at not cost. Does he want the 454 that bad? Good Luch with whatever you decide. |
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JEFF KOSTIS
Gold Member Joined: April-19-2005 Location: United States Status: Offline Points: 817 |
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Maybe worth while to go up a few piches on the prop. That engine has plenty of power to turn one of you dont need lightning hole shots. I run a 12x15 RH on my mustang and I can ski at 35 mph and the boat only revs at 2300 rpm. It just cruises along like having a car in overdrive. It does not do well pulling more than one skiier out of the hole, but I dont care. I can go for hours compared to before. Also, I know for sure CLIMBHIGH has by far the most correct answer!!!!
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Andrew
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The 454 would be worth at least double the price of a 351. I'd be keeping the big block, especially if you're using the boat for wakeboarding.
Having said that, the 351 will still be ok for boarding. You may get some small gains in ecconomy by switching, but the smaller engine will work harder for the same result. I wouldn't change it. |
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Brad_K
Groupie Joined: April-18-2005 Location: United Kingdom Status: Offline Points: 67 |
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The dealer is willing to do the conversion for free as he has the 351 (carb) sitting there from when he up-graded another customers boat to the GT-40 and he has a bigger boat with a 454 lump in (not a ski boat) with a cracked head.
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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if you swap a 454 for a 351 you will be one sick puppy!
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1979 Barefoot/454
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3335 |
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If you put in a 351 and then load up the boat with ballast, how much will you save? I suspect not much.
Consider doing tests with a vacuum gauge hooked up to the manifold, and adjust your main jets, advance curve, PV vacuum, PVCR diameter, and try a different props to maximize vacuum when at boarding speed, then you can quantify your changes with the guage and thus reap good economy. If your power valve is indeed open when just bording, you'll be sucking gas bigtime, up to 30% too much. Get your PV to open when need more than boarding-cruise speed, perhaps 2-3" vac minimum delta. There are two 454's.. one is 330 hp and has round ports. The other is 425 hp and has monster rectangle-ports and a larger cfm 4150 mechanical secondary carb. Its good for 55 mph and 5600 rpm with a 14x14 prop. I have an unconfirmed suspicion that the 425 454Hipo is std rotation while the rest are reverse. If you have the Hipo engine, the boat is indeed a rare find, and best left as is, cuz your a lucky guy. You'd be a fool to trade an engine with a $7-8K value for some tired unknown bone 351. Also explains why someone wants your engine. I suspect smart carb & ignition tuning specific to your usage can get you out of your pickle. Beware, too much prop will drop cruise vacuum, enough to open the PV and destroy fuel economy. A few degrees more advance at 20-2200 rpm while leaving the initial and final alone could boost savings significantly. If you have the original mallory distributer, chances are the advance mechanism is boogered up, the plastic bushing tend to disintergrate. here is a good introduction..read it about 5 times before undertaking, and I have found some errors in the document but for the most part its right on. http://realbig.com/pipermail/detomaso/2003-June/028198.html |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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bk
we were out sunday for about 5 hours also and the 79 barefoot-454 consumed approx 14 (50 litres)gallons of fuel. my engine is newly rebuilt with a freshened quadrajet. i went to the salvage yard picked up an automotive hei distributor for about $100. a marine unit hei will run about $350-. this is a major upgrade from the dual point setup. no vacuum advance necessary. |
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1979 Barefoot/454
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Brad, it takes fuel to produce power. When you think about it, trading to a smaller engine to save fuel is just a method of limiting power. There are some physics laws that apply. Ignoring changes in hull drag, engine efficiency, and internal engine and drive train friction, turning your prop at 50% of full speed RPM will result in approximatly 82% savings in fuel. (As compared to running wide-open-throttle). Turning your prop at 80% of full speed RPM will result in approximatly 50% savings in fuel.
I think you should try a boating trip where you seriously keep you hand off the throttle, so to speak. You may be surprised. I brought this up in another thread a few months ago. (I also mentioned that in view of what I said how do I run my boat? WOT all day long!) |
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Happy owner of a '66 and a '68 Mustang
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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I am going to restate what I said above to clarify: The power required to turn your prop at 50% engine speed (RPM) is 12% of the power required to turn it at 100% of engine speed. The power required to turn your prop at 80% engine speed is 50% of the power required to turn it at 100% of engine speed.
Anyway you say it, throttling back just a little saves a lot of gas. |
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Happy owner of a '66 and a '68 Mustang
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3335 |
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Good points jim,
Since its a quadrabog, perhaps disconnect the secondaries and board just off the primaries, and recheck fuel usage. Whoops, sorry mixed up originators.. emitchum, I suspect he chances the advance curve of your automotive HEI distributer being optimal for your application are nil. Best map the advance from idle to 4krpm every 3-400 rpm and compare to others. |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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runs too good to mess with gottaski, but if a marine msd or mallory falls off a truck i will stop.
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1979 Barefoot/454
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Brad_K
Groupie Joined: April-18-2005 Location: United Kingdom Status: Offline Points: 67 |
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I think i am going to stick with this engine and just it converted to gas, does anyone know how mush a set of manifolds would be?
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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emitchum,
You can always wait until you blow yourself up with the automotive HEI unit while you are waiting fro the MSD to fall of the truck. Not a wise move using automotive electrical equipment on a marine application. Also the vacuum advance is really going to help you a lot as well. There are times to be cheap and then there are times you are just plan stupid. |
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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grow up 79nautique
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1979 Barefoot/454
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john33617
Senior Member Joined: July-07-2004 Status: Offline Points: 182 |
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http://www.marinedieselusa.com/marine-engine-towsport.html
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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emitchum, I don't blame you for not liking the manner in which 79nautique delivers information, I have been his target also, but he is pretty much right on. I am the king of cheapskates but there is a reason marine ignition components cost more than auto type. No one would like to see your boat go up like a volcano on the lake which could happen if auto parts are substituted for marine duty components. Your auto engine operates in a well ventilated enviorment. Your boat engine operates in a relativly sealed enviornment. The theory is that marine electrical components are designed so when they burn up, like all electrical components eventually do, the flames are contained and will not find their way into the engine compartment - not necessarily so for standard auto components. This is not an area to try to save money. It's deadly serious stuff.
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Happy owner of a '66 and a '68 Mustang
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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i doubt that i am "plan stupid" or even plain stupid . i bought a boat with a seized engine with an automotive mallory dual point that someone had installed. the ignition i have in place was meant to be temporary and as soon as i get $400 ahead i will switch out the dizzy since the marine part thing is not a revelation. it is on my list. The msd 83606 does not have vacuum advance
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1979 Barefoot/454
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Ohh... Good. For me the marine part thing was a revelation and not too long ago either. You sound like you are not new to boating. I am brand new to boating. I have always thought of myself fairly comfortable around engines but I am alarmed by how much I am discovering that I don't know. Keep us posted on the progress. Do you have any pics posted?
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Happy owner of a '66 and a '68 Mustang
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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thanks jim
i just dont call people that i do not know cheap skates and stupid. i ran the boat f/s a while back and they have not pulled the ad yet. this is my second cc. my first was a 61 classic with a y block 292. (should of kept it too) my neighbor sold me the BF needing the engine rebuilt and now he would like first dibs if i turn loose...pics http://store.barefootcentral.com/browseproducts/1979-Barefoot-Nautique---Lexington--NC.HTML |
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1979 Barefoot/454
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emitchum
Newbie Joined: May-27-2005 Location: Spain Status: Offline Points: 19 |
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brad k
did you surrender your 454 chevy for the ford 351? the suspense is killing me. dont leave us hanging |
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1979 Barefoot/454
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