News from Moyer Marine

In This Issue:

Vacuum gauge indications

Tartan 30 & 34 standpipe

Top 10 no-nos

Greetings to our Atomic 4 customers, and welcome to our Winter 2010 email newsletter. We have compiled the following information that we hope you find helpful. For a complete listing of our Atomic 4 parts & services, you may visit www.moyermarine.com.

-"Are you operating in a vacuum"?

You probably have a gauge in your cockpit that informs you about your oil pressure, water temperature, perhaps even one that lets you know the RPM that your engine is turning. There are however other operating parameters which are relatively important that you don't know, simply because they don't always lend themselves to direct static indications on a gauge.

This missing information includes things like how well your valves are seating, how efficient your fuel mixture is, how hard your engine is working to produce the RPM shown on the tachometer at your favorite cruising power setting, or how much exhaust back pressure is produced by your exhaust system.

If you're willing to put forth a little extra effort, much of this additional information can be available to you if you learn how to interpret the indications on a properly installed manifold vacuum gauge.

Here are a few of the more important vacuum gauge indications for the Atomic 4 that we included in the instructions that come with the vacuum gauge recently added to our online catalog at moyermarine.com:

- Idle: 15” to 18”.
- Cruising at Universal's recommended 2000 RPM: (developing approximately 10 HP) - 9”. Lower vacuum indications would indicate a general declining of the overall “health” of the engine and the need of a tune up.
- Wide Open Throttle (WOT): Usually 1” or 2”

Here are a few of the more useful dynamic indications, meaning that they require interpretation of changes and/or rate of change (exhaust back pressure is probably one of the most important items on this list and is usually very difficult to obtain in any other way given the access limitation on most boats):

- Partially blocked exhaust system: (a vacuum gauge is particularly useful here where limited access behind the manifold precludes using one of our exhaust back pressure measuring kits to measure back pressure directly): Vacuum will go to normal at idle when engine is first started, but as RPM increases, the vacuum reading will slowly move to very low readings depending on the degree of restriction (could go to zero in worst cases).
- Improper idle mixture: Vacuum indication will fluctuate between 13” and 18”.
- Poorly seating valves: Vacuum will flick downward 2” to 3” from normal for any power setting.

NOTE: You can also review a considerable amount of instructional material on interpreting vacuum gauges on the internet by searching “Vacuum gauge interpretation”, as well as from the growing number of very seasoned veterans on the Community Forum at moyermarine.com.

-Tartan 30 and 34 standpipe mufflers

We've traditionally avoided use of the term “standpipe” in connection with exhaust systems, simply because it's so difficult to find a classic definition of what it means, and in most cases what people are really talking about when they use the term is their “water lift muffler”. That being said, the original exhaust configuration in both the Tartan 30 and 34 do seem to fit the term since the end of their extended hot section piping really does “stand up” through the middle of a 3” diameter jacket approximately 20” in height. Engine cooling water is plumbed into the top of the 3” jacket and together with the engine exhaust, cascades back down to an outlet near the bottom of the 3” jacket and out through the side of the hull.

We will be introducing (mid January) a stainless replica of the original Tartan standpipe muffler in our online catalog for Tartan owners who would like to retain the benefits of the original design. In addition to making very good use of limited space (the plight of most all sail boats), there are several obvious benefits of this design:

1) It's virtually impossible to get water back into the exhaust manifold by over-cranking the engine since water will simply flow out through the side of the boat.
2) When the engine is stopped, little or no water remains in the exhaust system so there is virtually no danger of water finding its way back into the exhaust manifold while sailing.
3) Since engine cooling water enters the system well above the theoretical water line, there is no danger of water siphoning in to flood the system if the raw water through-hull valve is left open.
4) Low exhaust back pressure.

Even failures of the standpipe design are somewhat easier to deal with than most other systems. In fact, the symptoms of a failure are so subtle that they are sometimes missed for long periods of time. In a typical failure mode, small pin-hole leaks develop at the base of the inner pipe as it enters through the bottom of the outer jacket which allows small amounts of engine cooling water to enter the hot section as the engine is running and for short periods after the engine is shut down. Early symptoms are usually limited to small amounts of steam leaving with the exhaust, and as the leak worsens, moisture will intrude into the combustion chambers sufficiently to cause sticky exhaust valves and eventually fouled plugs.

We thought it would be useful for the newer members of our Atomic 4 fraternity if we tried to list in one spot the procedural things that can so easily be avoided, and which will save many dollars, time, and in some cases even life threatening situations, if they're simply avoided.

1. Do Not: Start the engine before running the bilge blower for 3 to 5 minutes, or at any other time that gas fumes are detected.

2. Do Not: Leave the boat without insuring that the fuel supply is cut off from the engine either by a manual valve (preferred) or a normally closed electric solenoid valve.

3. Do Not: Reverse the polarity anywhere within your DC electrical system (reversing the plus and negative leads). To do so jeopardizes your electrical components and in worst cases (reversed polarity within the battery box) can lead to catastrophic destruction of the batteries themselves.

4. Do Not: Operate the starter of an Atomic 4 more than 5 or 10 seconds with the raw water through-hull valve open and the engine not starting.

5. Do Not: Connect the city water supply to the cooling system of an Atomic 4 to supply water for engine cooling when running the engine on land. Water should be provided in a five-gallon bucket and connected to the intake of the engine pump to provide the necessary cooling water.
NOTE: Risk of flooding the inside of the engine with water is very high when violating either of the two previous items.

6. Do Not: Operate in the “Forward” mode by holding the shifting lever against the forward clutch assembly. To do so places the throw-out bearing of the operating cone in a constant side-load (for which it was not designed) and will greatly shorten its life. Need we say that operating cones are on the very short list of endangered Atomic 4 parts?

7. Do Not: Tighten the retaining pin on the forward adjusting collar of the reversing gear before insuring that the tip of the pin is squarely in one of the notches of the collar. If the tip of the pin rests on the outside of the collar, it will surely break out a small chunk of the fragile cast iron pressure plate of the clutch assembly.

8. Do Not: “Hot-wire” across the Oil Pressure Safety Switch (OPSS) in the electric fuel pump circuit except for short periods of time when in a troubleshooting scenario. The OPSS is required by the US Coast Guard as a safeguard against ever leaving the boat with the electric fuel pump running, and its proper functioning could also save your engine in the case of complete and sudden loss of oil pressure.

9. Do Not: Rotate the pointer on the Master Battery Rotary Switch through “OFF” while operating the engine with one of the original 35 amp Motorola alternators installed. The large output diodes on these vintage Motorola's are very prone to blowing out if the load on the alternator is suddenly removed (as when passing through “OFF”).

10. Do Not (unless you have no other option): Change any parts or perform any other major maintenance during a troubleshooting scenario without first acquiring an MMI Service and Overhaul Manual, availing yourself of the wisdom contained in the relevant section(s) of the Community Forum.