Wingnutt
Petty Officer 1st Class
- Joined
- Jul 16, 2003
- Messages
- 255
Well after an additional year of work, due to many delays, we finally splashed our 2455 last Sunday!
Overall things went pretty good except for what I am hoping are a few minor problems.
First off, she has a rebuilt '88-90 350 in her with a slightly larger than stock cam. I am in contact with the PO for the spec sheet which he is searching for. But he said that is a very mild towing cam designed for mid range torque. I believe him since you can?t hear it at idle?plus he is my little bro who has run his own garage for over ten years. The original 305 was a solid mass of rust, so he started with a seasoned 350 four bolt main and went from there. All of the external parts, manifold, carburetor (Rochester Quadrajet) , distributor, starter ect are the original marine pieces except for the exhaust manifolds and risers which are new. We changed the old point system ignition to electronic as soon as I got the boat to eliminate any problems with that. The carburetor was rebuilt about five years ago, but it has had at least three loads of gas evaporate out of is since. The thermostat and impeller are new, along with a recent tune up. The last time the boat was in the water was four years ago to break the engine in. At that time my bro said that the boat ran great and had fantastic power?this was backed up by his wife and sons.
Now with the background information out of the way?
The first problem was a slight overheating issue. At idle she ran 180 on a 160 thermostat; raise the RPMs and she went right back down to 160. I know it sounds like the impeller but that is new, as in a month old new. Under a load (read that running on plane) she would heat up to around 190-210 depending on speed. At a 3500 RPM cruise is where she would get the hottest (200-210) and at a 2700 RPM cruise she ran around 190. I never ran more than a minute or two above 190. When I would stop and run the engine around 1500 in neutral, she cooled right back down to 160. Wait, it gets better, the first time I ran the engine on the muffs, she would heat up to 190-200, and I quickly shut her down and let her cool off. Backed her into the river on the trailer and she ran 180 at idle and 160 at higher engine speeds in neutral (no load).Tuesday when I ran her on the muffs, she wouldn?t go over 130! Weird huh?
Now for the truly bizarre. I have a laser thermometer which I also used and the thermostat housing, manifolds or risers never went over 180 when she was running warm, and Tuesday everything stayed around 120-130.
If that wasn?t enough, she was down on power?way down. According to my bro, the engine should be making about 300 hp and in a 3800lb boat should leap up onto plane. When I rolled the throttle on to bring her on plane, the engine response was sluggish and it had a slight miss. Open the throttle enough to engage the secondaries, she fell flat on her face, bogging and popping back up through the carb. The RPMs wouldn?t come up and I had to back off the throttle. I tried this several times with the same results. The misfire back up through the carb indicates a lean condition to me (I haven?t pulled the plugs to verify yet) so I started checking the fuel system which consists of: a 50GPH rated in-line cartridge type filter before a Lowrance fuel flow sensor then the stock spin-on filter/water separator and new fuel line. The in-line filter is new and I replaced the spin-on filter/water separator, no water or other nasties were is any filter. Also, the filter where the hard line attached to the carb is AWOL. When I acquired the boat, I pulled the sending unit and used an electric fuel pump on length of fuel hose to remove all of the old fuel. Then I wiped the inside of the tank (aluminum) the best I could. Then it set empty for three years before filling it up last week?Star-ton was added as a precaution. The vent is free and clear as verified by a nice flow of air when fueling up.
I feel it?s a safe bet that the carb needs rebuilt, but was wondering how much the timing would affect this. The distributor is the original 22 year old points type converted over electronic ignition and the base timing is set at 4 degrees BTDC. I am considering just replacing the distributor with a drop-in MSD marine replacement, but want to get some feedback first.
As far as having a shop check the curve, that?s a laugh. If anything, and I do mean anything is over ten years old, no shop around here will touch it. Forget trying to get information from a shop, all they want you to do is get in line and give them the money when they are finished. The marinas here are even worse, it any repair isn?t warranty work they will tell you don't want to touch it.
So feel free to toss out any and all of you ideas?I?m at a loss here and any assistance is greatly appreciated!
First off, she has a rebuilt '88-90 350 in her with a slightly larger than stock cam. I am in contact with the PO for the spec sheet which he is searching for. But he said that is a very mild towing cam designed for mid range torque. I believe him since you can?t hear it at idle?plus he is my little bro who has run his own garage for over ten years. The original 305 was a solid mass of rust, so he started with a seasoned 350 four bolt main and went from there. All of the external parts, manifold, carburetor (Rochester Quadrajet) , distributor, starter ect are the original marine pieces except for the exhaust manifolds and risers which are new. We changed the old point system ignition to electronic as soon as I got the boat to eliminate any problems with that. The carburetor was rebuilt about five years ago, but it has had at least three loads of gas evaporate out of is since. The thermostat and impeller are new, along with a recent tune up. The last time the boat was in the water was four years ago to break the engine in. At that time my bro said that the boat ran great and had fantastic power?this was backed up by his wife and sons.
Now with the background information out of the way?
The first problem was a slight overheating issue. At idle she ran 180 on a 160 thermostat; raise the RPMs and she went right back down to 160. I know it sounds like the impeller but that is new, as in a month old new. Under a load (read that running on plane) she would heat up to around 190-210 depending on speed. At a 3500 RPM cruise is where she would get the hottest (200-210) and at a 2700 RPM cruise she ran around 190. I never ran more than a minute or two above 190. When I would stop and run the engine around 1500 in neutral, she cooled right back down to 160. Wait, it gets better, the first time I ran the engine on the muffs, she would heat up to 190-200, and I quickly shut her down and let her cool off. Backed her into the river on the trailer and she ran 180 at idle and 160 at higher engine speeds in neutral (no load).Tuesday when I ran her on the muffs, she wouldn?t go over 130! Weird huh?
If that wasn?t enough, she was down on power?way down. According to my bro, the engine should be making about 300 hp and in a 3800lb boat should leap up onto plane. When I rolled the throttle on to bring her on plane, the engine response was sluggish and it had a slight miss. Open the throttle enough to engage the secondaries, she fell flat on her face, bogging and popping back up through the carb. The RPMs wouldn?t come up and I had to back off the throttle. I tried this several times with the same results. The misfire back up through the carb indicates a lean condition to me (I haven?t pulled the plugs to verify yet) so I started checking the fuel system which consists of: a 50GPH rated in-line cartridge type filter before a Lowrance fuel flow sensor then the stock spin-on filter/water separator and new fuel line. The in-line filter is new and I replaced the spin-on filter/water separator, no water or other nasties were is any filter. Also, the filter where the hard line attached to the carb is AWOL. When I acquired the boat, I pulled the sending unit and used an electric fuel pump on length of fuel hose to remove all of the old fuel. Then I wiped the inside of the tank (aluminum) the best I could. Then it set empty for three years before filling it up last week?Star-ton was added as a precaution. The vent is free and clear as verified by a nice flow of air when fueling up.
I feel it?s a safe bet that the carb needs rebuilt, but was wondering how much the timing would affect this. The distributor is the original 22 year old points type converted over electronic ignition and the base timing is set at 4 degrees BTDC. I am considering just replacing the distributor with a drop-in MSD marine replacement, but want to get some feedback first.
As far as having a shop check the curve, that?s a laugh. If anything, and I do mean anything is over ten years old, no shop around here will touch it. Forget trying to get information from a shop, all they want you to do is get in line and give them the money when they are finished. The marinas here are even worse, it any repair isn?t warranty work they will tell you don't want to touch it.
So feel free to toss out any and all of you ideas?I?m at a loss here and any assistance is greatly appreciated!
