zackie 77, did not mean to sound so negative. Just a little sick of talking about the OEM letdowns that the original motor was sold with. If the boat is as clean as you say, then that could be an indication that the previous owner cared for the boat and engine system. It would be nice to know what was actually done if you were able to find out from the previous owner. I guess my point is this: If the engine has never been overheated, you have good compression, cam seals were replaced, good oil pressure, cooling system is working properly, charging system is working as it should, risers and gaskets,manifolds, exaust flappers, etc. then run the heck out of it. These engines run strong but have to be maintained regularly. Not only do they run strong but they are pretty awesome on fuel. To give you an idea: last summer I took my kids down to the Jersey shore and ran the living puss out of the boat. (18 footer with 1988 3.7lx 180hp) The boat weighs approximately 2600lbs with fuel and gear. I ran approximately 8-9 hours that day. We traveled from Great Egg Harbor to Avalon came back up the Ocean side drove for another hour or two just putzing around because it was so beautiful and in a nut shell burned exactly $68.00 in gas. That is pretty cheap this day and age out on the water. I am guessing, but I bet conservatively I travelled at least 60-70 miles as the crow flies. (just guessing but I bet I am close). If the boat runs good at the moment then run the heck out of it and enjoy it before you go thinking about repowering. Make sure you do not run long at wide open throttle. I think you should be running wide open at 4600-4800. That is what is printed on my valve cover. I wouldn't run long at that rpm with that engine either. But if your prop is correct, it should be able to attain wot. I usually cruise at about 3600-3800 rpm. The engine seems to run pretty cool at that range and I still can travel around 25-28 miles per hour. Believe me, that is plenty fast in rougher water. You will see. I am no different than you except for the fact that I actually restored and repowered my boat and asked the same questions. (Trust me, I would never do it again! lol) Anyway, I did finish it after 3 1/2 years and store it in my garage. Storage is the key to preservation. I have never left the boat in the water except once at a lake in the mountains other than that the boat gets flushed with fresh water after every trip and washed and to tell you the truth it is nothing but work but I find myself doing it all just the same! lmao. It started out as a hobby that I really enjoy and have learned alot from these guys on this forum.They are great people offering a wealth of knowledge if you are just willing to listen. The first thing I would do is this:
1) how many hours are on the motor
2) Good compression? Good oil pressure? Mine starts at about 75-80psi but after hard runs will drop down to around 20psi which is a common occurence. As long as you have oil pressure at idle after hard run and it goes up with throttle you should be ok.
3) Is the distributor worn?, if so is it within tolerance as per manual (If not it could possibly cause detonation leading to engine failure)
4)Drain coolant and inspect at the 7:00 Replace with fresh 50/50. I think old coolants ph can be corrosive.
5) Make sure the weep hole at bottom of timing cover is not blocked up. It will be hard to locate. use mechanics mirror and light and take a piece of mechanics wire very carefully to see if it will insert into the weep hole. If not it is probably corroded and blocked as mentioned above.
6) Are all of your gauges working correctly? If not fix them. It could save your engine. I never take my eyes off of them when running hard as much as humanly possible. Oil pressure and water temp along with voltage are key to keeping this engine alive. Anything can happen like seaweed blocking the inlet on the drive causing an overheat so watch your gauges carefully.
7) Battery cable connections clean from batteries to starter? You should have a Delco starter as well as distributor. These engines take a good bit of amperage to turn over so make sure you got good wires, clean connections. Have someone turn over engine and feel battery cables to see if they get hot or even warm. That is usually an indication of either rotten wires or poor contacts either on the starter or the battery(s) themselves. I use dialectic grease and continuously clean terminals and connections because of electrolysis. check water in batteries! You will see! lol Nature of the beast! lol
8) The carb on your boat is probably a Rochester Quadrajet which is a NLA part so take good care of your fuel system. Inline filter to carb? I searched around for a spare and found one so keep it in mind. You can always change intake manifold back to a two barrel setup if you weren't able to locate a carb. I think there are two that you can go with. Just so you are aware, for the most part the 470's are all the same except as mentioned above pistons may have been upgraded along with distributors and starters along with 4" heat exchangers. I think early versions had Prestolite ignition systems (distributors) along with starters which had remote solenoids. (seperate from starter that's all) The later used Delco. Also, before I forget, there should be a small filter which screws directly into carb. Make sure it is clean!
9) How old is fuel pump? It should be a Carter mechanical pump which produces 4-6 psi. Make sure you don't replace with any higher than that or you will have all sorts of problems. Make sure the spacer behind fuel pump is intact. Pump will not work properly if the spacer is not in place. It is a cam driven pump on side of block. There is also a filter on the fuel pump that has to be routinely checked if your tank is old and dirty and you do not have an inline filter it could have crap in it. Also, after a long hard run you may experience a hard start condition. What happens is the fuel in the metal lines going into the carb. can actually boil causing a hard start no fuel condition. Merc. sold a fuel cooler for this problem but I have found that if you move throttle with the throttle only button and give it two full throttle strokes and then leave it to about 1/3 throttle, you can get it to start fairly easily. Just trying to save you from burning out your starter by turning and turning. You will see! lol
10) Pertronix electonic ignition system is a must for this engine. It makes cold starting alot easier, better power, better economy. Before you install the Pertronix make sure your distributor is not worn as mentioned above as per manual. It could cause detonation problems and possible engine failure if all is not well. The kit is relatively easy to install along with the 40,000 volt flamethrower coil. Don't go any higher than that with the coil because of the small distributor cap and heat issues just to be safe. You can regap your plugs to .040 but no more. I went with the Pertronix 8mm wire as well when I regapped just to be safe. Oh yeah, be careful with the installation of the Pertronix rotor. I pushed too hard and broke the first one I tried to install. Just warning you that's all. They will replace it free but you have to wait for the darn thing!lol
11) If you can, replace that damn rectifier, water cooled voltage regulator mess with an aftermarket alternator setup you would be ahead of the game. I have a 65 amp alternator that came with the kit. I paid like $400.00. Alot of money, I know. but great advantage to it just the same. No more dead batteries, boiled batteries (smell rotten eggs?) Hard starting and all the other problems that these things are notorious for. However, some old timers are still running it OEM and swear by the old points setup along with the original charging system. Make sure if you do put an alternator eventually, that you cap the two wires off from rectifier (generator) because you will still be putting out alot of A/C power and it could cause problems like a short which could cause a fire. I removed the guts and all out of my original charging system because of this potential risk. It was a bit of work removing the pulley off of crank via a puller but feel that I did the right thing. Like I said, you don't have to do what I did, but make sure the wires are capped off properly! These wires could possibly cause enough of a short to burn a hole in your oil pan if they were able to touch it causing all kinds of misery. Just warning you, that's all
12) Change your oil regularly and use good oil. I will not tell you what to use because everybody has their own oil that they like as long as the manual recommends it use it. Use a good Merc filter. I change my oil every 50-60 hrs. That's actually like almost the whole season. That's a good few hours on the water, you know? Call me anal, but my oil looks like Aunt Jemima syrup on the stick, not black and nasty and thinned out. I got too much money in this engine to abuse it. I would rather spend the money on oil than burn up the darn thing. It's just to much work to ignore.
13) They do sell a Mallory distributor for the 470's which I was told is superior to the OEM changeover to the Pertronix which is a halls effect triggering device for the ignition. Alot of guys go with the Pertronix because of the cost and most of the time it works pretty well if all else above is well and good.
14) Finally, make sure you replace your impellar on the sterndrive as per manual. Engine absolutely depends on this for cooling. You will overheat the engine for sure if the impeller goes south. You will be broke down with a possible overheat which means head gasket failure which means $$$$$$
I posted all this stuff tonight because I am trying to enlighten you about your engine system. all the best, Tom
