Motor conversion, help?

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« on: June 12, 2018, 05:02:36 PM »
I'm new to the forum so please bear with me, I just picked up a 1971 sidewinder Cutlass, originally setup for a outboard but i'm contemplating going with a v-8 and jet drive simply because of the lack of different assemblies needed as opposed to a I/o setup. My hope is that I can use a Chrysler 360 with water cooled headers, here's my issue, where do I start? Engine mounting is my biggest concern


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« Reply #1 on: June 13, 2018, 06:50:14 AM »
First thing, does it have stringers and what does the bottom of the boat look like?  Some keel shapes don't lend themselves well to feeding water into the jet pump.

I'm assuming you mean the LA-360 and not the 5.9L Magnum?  I have quite a bit of experience With these engines and frankly, you are handicapped on every single aspect of this engine, except for the connecting rods.  I don't think that the small block Mopar is really a good choice for a jet boat.

Moving forward, because I understand that sometimes you just gotta do it, for better or for worse.  Assuming that the hull lends itself to the installation of a jet:

The easiest, most versatile, and most secure way to mount the engine is with a rail kit.  You will need to fabricate engine plates from 3/8" aluminium plate.

Pick up Mopar Circle Track Chassis 8th Ed. book, it has a lot of valuable blueprints of you decide to make your own parts.

The rear plate will mount to the bellhousing surface.  You will need to run a top-mount starter because Mopar starters mount to and register in the transmission bellhousing, a Mercruiser top-mount starter system will need to be employed with the correct location for your manual transmission flywheel.

The front engine plate will most likely attach to the timing cover, using the five water pump bolt locations.  Sandwiching the engine plate between the block and timing cover will open a can-of-worms with the crankshaft seal, front two oil pan bolts, and the oil pan gasket.

You will need to make a PTO, unless you can find one.  Crankshaft flange dimensions can be found in the Mopar Circle Track Chassis or just about every Mopar engine book.

As for exhaust, you might be able to find some logs, since these engines were used in marine applications, but I think they would be pretty rare and choke off the already terrible flowing exhaust ports.  I really think you will need to fabricate your own headers.  You might be able to modify or adapt small block Chevy exhaust, I never looked into this in any depth.

Post good pictures of the bilge area and the bottom of the boat to see if it is even feasible.

Good luck,

"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013


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