OMC Johnson Evinrude NEW OEM 384073 Piston Ring Set .030 O.S. 9.5 HP 64-73 0810

OMC Johnson Evinrude Piston Ring Set, .030 Oversize — Part Number 384073

Brand: OMC Johnson Evinrude | Condition: New Old Stock (NOS)

Genuine OMC piston ring set in .030 inch oversize, part number 384073, for the Johnson and Evinrude 9.5 HP two-cylinder outboard built from 1964 through 1973. This is the ring set a rebuilder needs after the cylinders have been bored thirty thousandths over standard — the specific size that lets a tired 9.5 get a second life instead of becoming a parts motor. This number is No Longer Available from BRP. Crowley Marine’s catalogue shows it with no price and availability listed as never, and no replacement number was ever issued. The standard-size ring set for the same engine is still supplied and still sells for around sixty dollars; the .030 oversize set has simply run out of the world. If your 9.5 is already bored .030 over, this is not merely the convenient option — it is the only correct one.

Condition Details

New Old Stock — never installed, never fitted to a piston. This ring set has been in dealer or distributor inventory and is sold exactly as it came off the shelf. Piston rings are cast iron or steel and were packed with a light protective oil film, and dry indoor shelf storage treats them well — the ring faces and end gaps on an uninstalled set are exactly as they left the factory. Packaging may show shelf wear, dust, handling creases, faded or discolored printing, old price stickers, or shelf dirt from long-term storage, and the box or envelope may have been opened for inventory counting. The rings may carry light surface oxidation or storage patina on the outer wrap. Please see the photos for the exact contents of the package. If you want the correct oversize rings for a 9.5 rebuild and you do not care that the box has been sitting in a parts room for fifty years, this is the listing for you.

Specifications

• Part Type: Piston ring set
• OMC / BRP Part Number: 384073 (also written 0384073)
• Size: .030 inch oversize (.030 O.S.)
• Engine: Johnson / Evinrude 9.5 HP, 2-cylinder 2-stroke
• Engine Displacement: 15.2 cubic inches
• Standard Bore: 2.310 inches
• Bore This Set Is For: 2.340 inches (2.310 standard plus .030 oversize)
• Stroke: 1.812 inches
• Diagram Location: Crankshaft & Piston group, reference 3
• Status: No Longer Available from the manufacturer — no replacement number
• Sold As: See photos for exact package contents and ring count
• Condition: New Old Stock

OMC did not publish a ring count or individual ring dimensions for this set in any public catalogue, and because the number is discontinued no current retail listing carries them either. If you need the ring count, ring widths, or end gaps confirmed before you buy, message me and I will open the package, count the rings and measure them for you.

Superseded & Cross Reference Part Numbers

• OMC 384073
• OMC 0384073 (BRP seven-digit form of the same number)

There is no supersession on this part. OMC never issued a replacement, which is precisely why it is gone rather than renumbered.

Important — this is an OVERSIZE set. Read this before ordering.

• 384073 is .030 oversize. It fits only a cylinder that has already been bored .030 over standard — a finished bore of 2.340 inches.
• 0379360 is the standard-size ring set for the same engine and is a completely different part. It is still available new at roughly $59.97.

These are not alternates for one another. Oversize rings will not go into a standard bore, and standard rings in a bored cylinder will not seal — you will have no compression, no crankcase signal, and a fresh rebuild that has to come apart again. Measure your bore, or ask your machine shop what they took it to, before you order. If you are not certain what size your cylinders are, message me and I will help you work it out. I would much rather talk you into the right set than sell you the wrong one.

Features

• Genuine OMC factory part, not an aftermarket ring pack of approximate size
• Discontinued and No Longer Available from BRP — no current production, no replacement number, no substitute
• Correct .030 oversize specification as engineered by OMC for this engine
• Unused: factory ring faces, factory end gaps, no wear, no distortion from prior installation
• Cast ring material and radial wall matched to the 9.5 HP cylinder — not a generic ring cut to fit
• The missing piece that lets an already-bored 9.5 go back together
• Fifty-year-old shelf stock in a part that does not degrade on a dry shelf

Application

Johnson and Evinrude 9.5 HP outboard motors, 1964 through 1973 — the two-cylinder, 15.2 cubic inch powerhead with a 2.310 inch standard bore and 1.812 inch stroke. OMC built this engine for a full decade with very little change to the powerhead, so the ring set covers the whole production run. Documented in the factory Crankshaft & Piston parts group as reference 3, the .030 oversize alternative to the standard ring set.

This set is for engines bored .030 over, not for standard-bore engines. Confirm your bore size before ordering — see the warning above. If you give me your engine model and serial number I am happy to help confirm you are looking at the right engine family, though only you or your machinist can confirm the bore size.

Worth knowing if you are rebuilding one of these: the 9.5 is an engine where parts availability has been closing in for years. Several items for it are already obsolete, including the early fuel pump repair kits and the pre-1967 front motor mount, and there is no aftermarket carburetor kit for it at all. Oversize rings are now on that list too.

Why Choose OMC Johnson Evinrude?

Piston rings are the part of an engine rebuild where substituting by dimension alone goes wrong most often. A ring is not just an outside diameter — it is a radial wall thickness, an axial width, a specific free gap, a specific material and a specific face profile, all chosen for the cylinder material, the port layout and the operating temperature of the engine it belongs to. OMC specified these rings for a 2.310 inch bore two-stroke with a particular port arrangement, and the .030 oversize set was produced to the same specification at the larger diameter. Rings sourced by rough measurement from a generic catalogue may seat wrong, may not seal at the ports, or may break a land. On a fifty-year-old powerhead with needle-roller main and rod bearings, where a failed ring sends debris straight into bearings you cannot easily replace, that is not a risk worth taking to save a few dollars. This is the factory part, in the factory size, unused — and since it is discontinued, unused factory stock is the only place it still exists.

Returns

30-day return policy. If this part is not right for your application, open a return request through eBay within 30 days of delivery and I will take care of it. Please confirm your bore size and fitment by part number before ordering where you can — I am happy to help you check.

Thank you for looking at this listing. QBS Parts, Inc has been supplying hard-to-find and discontinued marine, industrial and engine parts for years, and we know that when you are mid-job on a boat the part you need is the part you need. Everything we list is inspected before it goes out the door and described as honestly as we can describe it.

If anything about this part is not what you expected, or if you have a question about fitment, measurements, or what is in the package, please contact us first and give us the chance to make it right. We would much rather solve a problem for you directly than have you leave feedback about one. A message gets answered quickly and we will do whatever we reasonably can to sort it out.

QBS Parts, Inc — Gardena, CA