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Graymarine 4-112

By Allen Edwards

Overview

The Gray Marine 4-112 engine in my Lapworth 36 is a gas powered engine typical of pre Atomic Four engines. After blowing a head gasket at 150 hours and paying $75 for a new one, I looked for parts for this engine.

Gray Marine 4-112

This engine can be identified by the Y112 casting id on the head. It is based on a Continental Y112 which is used in fork lifts and tractors. That makes parts readily available as many of these are still in service. Interestingly, they are also used in welders. This short page documents some useful information.

Head Gasket

Fel-Pro discontinued this gasket November 2021. I am looking for another source as of July 15, 2022. Found two on eBay. Search was for Gray Marine Head Gasket. I think I got the last one. I had 3 but used two with a blown head gasket followed by a stripped head bolt. About that time, VanNess Engineering had some made. I bought two and was happy to pay 5x the price they sell for from sources that don't have them. Things are always cheaper from places that don't have them.

Spark Plugs

The Gray Marine cross references list Champion D16 (516). The Continental Y112 lists D21(502) which is one hear range higher. I might consider trying the D21 for a bit less chance of fouling. My plugs never look like they are running hot. Here are a couple of handy references to help determine if plugs are too hot or too cold.
sparkplugs
sparkplug2

Distrubtor Condenser

The engine rebuilder for my engine put the wrong condenser in. One day I had absolutely no power and the enting would quit right away. The correct condenser is an Standard Motor Products AL106

Carberator

The Marvel Schebler Carburetor Manual is on L-36.com HERE.

Manual

The Maintenance Manual is on L-36.com HERE

Water Pump

I have had good luck and bad luck with water pumps. The good luck was with Depco Pumps in Florida. The pump is a Sherwood Q10840. HERE is a pdf,

Impeller

Sherwood 10077. Kit includes gasket 10077K. Seems to be widely available

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