This standpipe muffler is made of 316 stainless steel. Don Moyer’s custom internal design of the water and exhaust flow make it virtually impossible for cooling water to back up into your Atomic 4 (a problem with many sailboat water lift exhaust systems, one of the primary causes of stuck valves, and poor running). His design also provides improved cooling of the outside of the standpipe to accommodate mounting in restricted spaces. Overall height of the body of the standpipe is 12″, the outside diameter is 3″. There are 1-1/4″ NPT male pipe threads on the exhaust inlet pipe extending below the muffler and also on the cooling discharge on the side near the bottom of the outer chamber. The inlet for engine cooling water is on top of the muffler and has 1/2″ NPT female threads. Stainless mounting loop brackets included. Note: To help with the final pipe fitting of your exhaust system, we also recommend our stainless steel exhaust flex coupler.
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This stainless steel exhaust flex coupler serves two purposes: First, it offers a vibration dampener between the engine and heavy exhaust piping, reducing stress on your exhaust manifold. Second, it adds a small amount of wiggle room when trying to fine tune your exhaust fittings, when you just need a “bit more” flexibility. The flex coupler should be installed as close as possible to your exhaust manifold.

The ends of the coupling have been modified in our welding shop with stainless steel 1-1/4” NPT nipples, so they can be plumbed directly into your hot exhaust section. This provides a clean uncluttered approach, without the need for multiple clamps.  The flex section and end nipples are stainless type 304, and the flanges are stainless type 409.
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One of Don Moyer’s first Atomic 4 kit upgrades, and loved by many of our customers. This low profile kit enables you to check your oil level without having to reach back over your engine. The extension tube attaches over the original short dipstick tube by a small Allen head set screw, or convenient thumb screw. All hardware included.
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Anyone who has rebuilt an Atomic 4 can relate to the frustration of not having the right fastener when you need it, since many are too rusted, or broken after disassembly to reuse. The External Fastener Kit contains the Grade 8 hardened bolts, nuts and washers needed for the external reassembly of your Atomic 4. Conveniently labeled in a multi-bin organizer, this kit includes the hard to find “odd” bolt lengths and custom undersized brass washers not readily available at your local hardware store.
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With an overall length of only 3.5”, this tool is designed to remove the impeller from the shaft of your MMI 502 flange or 501 pedestal pump with the pump mounted on the engine or removed from the engine. With a little practice, you can remove an impeller using only one hand if necessary, which is very convenient when working in the most restrictive on-board installations. Our puller will also work on Oberdorfer 202M and 201M series pumps with one caveat; the shaft will be coming out with the impeller due to Oberdorfer’s use of a snap ring, so you will need to have enough space to remove the impeller/shaft assembly after the impeller clears the pump housing.
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