MSD FOR A 525SC
Question: I have a 1998 Sonic 26 with an OEM HP525SC that has 200 hours of running time on it. I also have a Scarab 22 with a 7.4-liter engine that has an MSD ignition (box, distributor and coil). I want to put the MSD system in the Sonic.

Will I see any difference? What initial timing and curve should I run? Also, do you have any other recommendations to make the HP525SC run better?

Ed Springer
Valley Lee, Md.

Answer: Adding the MSD ignition system is definitely a step in the right direction for your Mercury Racing HP525SC. You will have a stronger spark at idle speeds, which minimizes misfiring, and you also will be able to create a more desirable advance curve. Additionally, you can bump up the rev-limiter a little (not too much for your flat tappet hydraulic cam, though).

I would recommend using the full MSD marine system including the distributor, box, rev-limiter, coil and ignition wires. The correct distributor for your engine is the MSD Part No. 8360. I would use the new 6M-2L marine box that incorporates the Soft Touch rev-limiter, which is MSD Part No. 6560. We stopped using the traditional oil-filled coils a few years ago and are now using the MSD Blaster SS Coil (MSD Part No. 8207). This is a non-oil-filled coil (no oil leaks) that is providing excellent service and performance.

Finally, you will need to upgrade your ignition wires. The best choice for your engine is the MSD Part No. 31489. This is the MSD 8.5 mm Super Conductor Wire set that has the correct ends for the new style distributor cap and has 90-degree spark plug boots. Use the black bushing in the distributor and the light blue advance springs.

This combination will result in the shortest advance curve (about 20 crankshaft degrees) that is at full advance by around 2,500 rpm. Set your total timing at about 32 to 34 degrees at about 3,000 rpm. Thirty-four degrees total advance is fine as long as you can get decent premium pump gas. Engines that run too retarded create a lot of exhaust heat that can be detrimental to exhaust valves and exhaust systems.

Additional performance gains can be realized for your HP525SC by adding a SuperChiller intercooler. Using the SuperChiller will increase the engine's output by 60 to 75 horsepower. The kit comes with everything you will need including a smaller diameter blower pulley.

Using the supplied pulley will raise the boost level. That higher boost level in combination with the denser charge created by the SuperChiller will result in a significant power increase. The cooler charge created by the SuperChiller helps protect the engine from detonation created by the heat of the compressed air from the blower. If you add the SuperChiller, total timing advance will definitely be best at 34 degrees BTC.

If you add the MSD ignition and the SuperChiller to your HP525SC in your Sonic, you can expect an 8- to 10-mph increase in top speed. It is likely that you will have to go to a higher-pitch prop to realize the maximum potential of the new power level.

AERATED FUEL?
Question: I recently converted two 454 MerCruiser engines from carbureted to MPI with Edelbrock Pro Flo systems. I currently have both engines dialed in at a 12:1 air/fuel ratio. Maximum spark advance is 33 degrees at 3,000 rpm. Once the engines reach 3,000 rpm and higher, I sometimes experience an intermittent backfire through the throttle body, which would indicate a lean condition. According to my air/fuel meter that is not the case.

The system as set up now relies on a single high-pressure pump to supply fuel. Pressure is also good and stays steady all the way up the rpm range. I do not have a fuel cooler. I am thinking that I am getting air bubbles in the fuel either from boiling or from the tank itself. Some days, the engines run flawlessly, the next day the popping returns.

My proposed solution at this point is this: Reinstall my OEM mechanical fuel pump that will fill a 1-gallon slosh tank. The high-pressure pump will draw from that and my return line will pass through that small tank and then back to the main fuel tanks. I will also add fuel coolers to the system. If I can find some, I am hoping this small tank will eliminate any air bubbles from the tanks and the coolers to get rid of boiling, if any.

Engine room temps are 110 to 120 degrees. I'm also running a hotter water temperature to satisfy the ECM at 190 degrees. Any ideas?

Peter Clarke
Cuttingsville, Vt.

Answer: If you are returning all fuel to the tank, it is unlikely that your problem is associated with boiling or aerated fuel, assuming that your fuel system is correctly installed and there are no leaks on the suction side. Starting at the fuel tanks, make sure that the pickup tubes are sealed to the fittings in the top of the tank. Some fuel tanks have a plastic tube pressed onto a nipple that is connected to the pickup-fitting assembly. Over time, the plastic tube can stretch and lose its positive seal, which can allow air to enter the fuel stream from inside the tank.

Next, make sure that all of your fuel-line fittings and hose connections are tight and sealed. The high-pressure fuel pump must be mounted low in the boat. It is best if the fuel pump can be mounted below the level of the fuel tank. If the fuel pump is mounted too high, it can cavitate and cause the fuel to aerate. You should have a water/fuel separator filter between the tank and the fuel pump. And, you should have an inline micron filter between the fuel pump and the injectors.

The water/fuel separator protects the fuel pump and system, and the micron filter protects the injectors from minute particles or debris that cause pump failure. If your problem is more prevalent when the fuel level is low in your tanks, I would be suspicious of a problem with the inlet part of the fuel system.

Mercury Marine tried eliminating the manual diaphragm-style supply pumps on some of the fuel-injected motors a few years ago. One of these was the HP500EFI engine.

The engine seemed to be fine during the validation process. But with all the variables in actual use, there were many cases of engines with vapor-lock conditions. A kit was created to retrofit these motors that included the installation of the original-type supply pump system.

The difference with these motors compared to yours is that they do not return fuel to the tank. Instead, the Mercury Racing HP500EFI and HP525EFI return fuel to the fuel filter assembly. Because you are returning fuel to the tank, I do not believe that you need a supply pump to feed the high-pressure fuel pump.

A fuel cooler is always nice to have and would be mandatory if you were not returning all fuel to the main tank. It would be good to have a fuel cooler in the return side of the system, but I don't think it will solve your problem.

Don't overlook the basics. Sometimes we get so focused on what we think is causing the problem and overlook some of the basic principles that could cause the same problem. Make sure the ignition system is operating correctly. Check for problems with spark-plug wires, distributor caps, magnetic pickups and so on. I have had a few cases lately where a reluctor in the distributor was loose and caused erratic timing. If your engine is misfiring, it can actually cause a richer reading on your air/fuel ratio meter.

If your fuel system is sound, and the electronics are in good working order, I think that your problem is most likely associated with that 190-degree engine temperature. That temperature is a little too warm for a performance marine engine, especially a non-closed-cooling engine.

At 190 degrees, with your raw-water-cooled engine, it is very likely that you are getting steam pockets in your cooling passages especially adjacent to the exhaust valve seats in the cylinder heads. Do you have any idea what your oil temperature is? I can imagine that it is high as well. It is possible that your problem is associated with detonation or preignition.

I advise that you lower the water temperature by changing the thermostat and then having the ECU programmed to allow the motor to run with normal parameters at the lower temperature. Remember: Heat is death.

ONE ENGINE: TWO DRIVES OR JET PUMPS?
Question: I'm a boating novice and maybe my question here is embarrassing, and the answer might be obvious, but here goes:

Why don't we see jet drive or I/O drive systems on runabouts with one large V-6 or V-8 engine driving two jets or outdrives instead of the two smaller V-6s or four cylinders, each with their own drive? I know there would be no independent rpm control for slow-speed maneuvering, but with a jet drive I don't see the problem there.

You would just have to modulate (feather) the reverse diverter. I would like to see Yamaha or Sea-Doo place one engine between two jet drives on their 21- to 23-footers with separate belts going to the two jets. Is this doable?

Robert Williams
Punta Gorda, Fla.

Answer: Two drives behind one engine in extremely high-performance applications has been tried with limited success. IMCO marketed a one-into-two gearbox a few years ago that was made by SCS. It was sort of a backward version of the gearbox that is used to couple a pair of fire-breathers together on a tractor pull rig.

I tested a ski-race boat a few years ago that had one big (1,200 to 1,400 horsepower) fuel-injected turbocharged engine driving a pair of Bravo-style IMCO drives. This setup was a great alternative as opposed to trying to manage the torque of a single No. 6 drive on the back of the narrow-beam 21-foot V-bottom.

The boat was unique and was an absolute rocket out of the hole, which is what is necessary for pulling a skier up quickly and being the first boat to the turn in a ski race. On the larger scale, I tested a full-size Nordic with a similar IMCO setup. The Nordic was fitted with a high-horsepower, Whipple quad-rotor motor.

As I remember, the performance was about on par with what a couple of motors with the same combined horsepower would have been in that model. An idler gear was necessary on one side of the gearbox because Bravo drives can only operate with a standard input rotation. The drives could be shifted in opposite rotations at the same time, but the propeller speed during docking operations had to remain the same for both drives at all times while in gear.

In the performance world, jet pumps seem to be best for lighter-weight boats. The jet boats are also popular where boating is done primarily in shallow- water rivers.

The dual jet pump setup that the watercraft companies are using in their boats works well in accommodating the use of products they already make and have validated in their PWC.

Recently, Trident Boats experimented extensively using a huge power (950 horsepower) motor driving a pair of traditional jet pumps such as Berkley, Hampton, Dominator, etc. In Trident's case the pumps were Berkley model 12JG with "A" impellers. Their boat is a performance deck-boat catamaran.

With a 950-hp motor, Trident was only able to attain a disappointing 75-mph top speed with huge fuel consumption and minimal reliability. Part of the problem was the intake design on the twin pump setup. Most of the problem relates to how much power it takes on an increasing scale (with diminishing output) to run the jet pumps.

The bottom line is that the deck boat hit a wall, partially because of drag created by the pump inlets. Trident thinks they could have added 500 more horsepower and the boat may not have gone any faster.

Ultimately, the dual jet pump project was scrapped after considerable expense and effort. Instead, an identical boat was outfitted with a conservative Ilmor 550 Viper engine and Platinum Bravo drive setup.

Almost out of the box, the same boat ran 91 mph with great handling characteristics. The previous dual jet pump setup used tons of fuel, which averaged a half-mile per gallon.

With the Ilmor package, the same boat was able to get 2 to 3 mpg, depending on the speed. Needless to say, every Trident that has been built since is equipped with a single Bravo-style drive. Jets are no longer offered.

ENGINE FOGGING
Question: I would like to know if you think it's a good idea to fog my engines after each outing. I would also like to know how it's done? I have two Mercury Racing HP600SCi engines in a Formula.

Andrew Brody
Miami

Answer: The term "fogging" describes the practice of dumping or spraying some sort of moisture-displacing, lubricating fluid in the inlet system of the engine during the final shutdown process.

Fogging is more commonly performed on marine racing engines that are carbureted. It is performed by pouring a calculated amount of a penetrating lubricant down the carburetor while the engine is being run at an elevated idle speed.

The first step is to elevate the rpm with the flame arrestor(s) off. Then, the fluid is poured into the carburetor(s) in small amounts while the rpm is elevated slightly to compensate for the excessive rich condition. Properly performed, there will be significant smoke emitting from the exhaust pipes.

At that point, when the engine is allowed to return to idle, it will probably die. Be careful not to pour too much penetrating oil at once, which could result in hydro-locking the engine. Fogging results in the valves, valve seats, cylinder walls, pistons and ports being coated with the oil that helps prevent rust while the engine is sitting for a long period of time.

The fluids that are most commonly used are WD-40, Marvel Mystery Oil and ATF. I always used WD-40 or Marvel Mystery Oil when we were shutting down our carbureted and supercharged racing engines in offshore and Grand National race boats.

These race engines were usually run in severe environments. Sometimes they got wet from driving through rooster tails. Large overlap camshaft profiles combined with frequent header leaks commonly resulted in moisture accumulating in the cylinders.

Your modern marine supercharged, fuel-injected engines are completely different animals. I don't think it is necessary to fog the engines after each use. I do see a value in fogging them a little before they go into storage for the winter, though. It also is a good idea if you live in a humid environment such as Florida.

On fuel-injected engines that have horizontal throttle bodies, the only way fogging can be performed is by using some kind of sprayer or aerosol. Usually, aerosol sprays do not emit enough spray to be effective. A new and clean garden sprayer works pretty well. Make sure that you do not use a fluid that could result in clogging the injectors. On a fuel-injected motor, I would use Marvel Mystery Oil for fogging.

Be aware of this: When you perform the fogging procedure to your engines, it will create quite a bit of smoke, which might offend someone these days. And when you start the engines for the first time when they are brought out of storage, they also will smoke quite a bit.

WHAT IS NEUTRAL?
Question: I am just getting into boating. I would like to know how to read drive and tab indicators. What are the neutral positions on the indicators?

Demetri Katos
Astoria, N.Y.

Answer: When it comes to mechanical indicators on drives and tabs, there are at least a half-dozen brands, and that many more indicator cards. Some have numbers starting at zero and going up, and others count down from about three to zero, and then back up to eight or so.

Considering the varying systems and the human element of cable adjustments, the "neutral" position could be just about anywhere on your indicator.

So how do you know what the "neutral" position is on your drives and tabs? You will have to find out for yourself and mark your indicator panels. With the boat out of the water and on the trailer, use the trailer jack to level the boat. In most cases, using a level on the keel or chine near the transom will give you a good indication of when the boat is level. Then, have someone trim your drives to a point where the cavitation plates or propshafts are level (parallel) to the keel. The indicator reading at the helm with the drives parallel to the keel would be "neutral" for your boat.

The procedure is similar for the tabs except a straightedge is used to determine the neutral position. The tabs are considered at a "neutral" position when the bottom surface of the tab is parallel with the running surface of the bottom just in front of where the tab is mounted on the transom.

Most trim tabs are mounted about a half-inch higher on the transom than the running surface. If you place the straightedge on the running surface of the bottom just in front of the tab, and there is a half-inch gap between the straightedge and the tab near the transom, the neutral point will be when there is also a half-inch gap at the trailing edge of the tab straight aft. Once this position is attained, note the indicator reading at the helm. That is the neutral position of the tabs.

This procedure also will alert you if the indicator cables need to be adjusted. If there is a difference from side to side on the indicator panel when you have the trim at a level position or the tabs set the same, the indicator cables should be adjusted to result in the same reading at the helm. Be advised that there is a certain amount of slack in the indicator cables and that longer cables have more slack than shorter ones.

That being said, it is always best to approach a setting from the same direction. By this, I mean that you should trim both drives up to the desired checking point without having to adjust one back down. A minor adjustment in the opposite direction could result in no movement of the indicator because of the slack in the cables.