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Chrysler M225 Info Needed

1stgenbird

New member
Hello. I am new to the forum and hoping to find some info on a Chrysler Marine Slant 6 150hp motor that is in a old boat I just bought. The boat is a late 60s Silverline that came out of storage in CA and the last registration tag is 1978. The engine is mated to a Volvo Penta outdrive.
The motor is cosmetically in great condition and I fired it up very, very briefly to ensure it would start before I bought it but needs some maintenance to get fully functional.
I am familiar with the slant 6 as I had that engine in the first car I owned, but have some questions on the marine version.

I have posted some photos of the ID plate hoping someone can decipher it as to the year of the engine.

Also a photo of a housing that I believe is where a thermostat goes as there was nothing in there when housing was opened but the diameter is larger than the typical automotive thermostat, and the raw water pump that I know I will need impeller(s).

I initially thought the boat was a 1966 model as that seems to be the last year that this engine was offered as subsequent years it looks as though Mercruisers were the power of choice but the plug wires on the motor are date coded 1968 so I'm not sure.

Any info will be appreciated. Thanks in advance.
 

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1stgenbird,
I see this post is well over a year old but i though i'd respond and see if we can connect to share info. I have a '68 Silver Line Deville i bought about a year ago with a very similar set up to your and I'm always trolling the internet for info on the slant as used in marine applications. I have both the original owners manual to the boat and managed to get my hands on a service manual for marine/ industrial late 60's slants

Useful info I've learned so far
- on the Volvo outdrive it is extremely easy to change the prop rotational direction. use the motors ID plate to figure out which direction was original and then change it if it has not yet been done and it will significantly increase the life of the gearing. The best and most affordable source for props is Propco https://www.propcopropellers.com/

- They typically had marine specific Carter BBS carbs and if the model number tag is missing it is extremely difficult to chase down what it was without sending it to an expert. fortunately the automotive rebuild kits will work.
- While many of the components are shared with the automotive version of the slant be very careful because not all will crossover.
- the M225 made max HP at about 3K RPMs
- if you are looking to increase HP or torque be careful as these things are under-square engines and have unique design characteristics. You can learn quite a bit about this from Uncle Tony https://www.youtube.com/watch?v=b8Y96xywS-E
 
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