Posted by Jack Smith on December 20, 1998 at 15:44:51:
In Reply to: Diff between Chrysler Marine and Dodge flatheads? posted by Chris on December 19, 1998 at 10:40:27:
Chris,
The Chrysler Marine engines were similar, but not identical, to the truck engines. The block casting was different, so was the head casting, and the crankshaft. The blocks had a cast and machined port that took a triangular shaped bolt-on flange right where the bronze water distribution tube came out near the end of the block. The bronze twin-shaft & gear positive displacement style raw water pump, which was gear driven from the crankshaft, forced engine cooling water under cconsiderable pressure into the distribution tube to cool the valve seats in the block deck. The plumbing from the pump to the block was hard copper or bronze, and consisted of a tube going to this distribution tube port, as well as one going to the external engine oil cooler. The marine engines also had a modified cylinder head that mated to this water manifold. The marine intake manifolds were different also, and used an updraft carb, with a flame suppressor instead of an air cleaner. (no dust at sea!) Exhaust manifolds were water cooled, and had large cast iron jackets around the exhaust runners. Marine versions also had gear driven camshafts, (opposite rotation from a chain driven truck cam) and the crankshaft nose was modified to couple with the reversing gear/transmission. The gear was also made by Chrysler, and shared engine oil in some versions, both for lubrication and for hydraulic pressure for the gear change actuator, this being managed through a hollow crank nose with a metering port screwed into it. Thus, the crank nose had two gears pressed onto it, (requiring a very large press to remove!)one to drive the camshaft and gear driven accessories, as these engines used no belts, and one to drive the transmission. The engine oil pump was much higher in volume than the truck pump, and used a much stiffer relief valve. All marine versions came with cast iron oil pans, some had sodium cooled exhaust valves, and all had remote solenoid operated starters with a manual (emergency) pushbutton on board the starter. Since these engines were designed to drive off the crankshaft nose rather than the flywheel, they had partial flywheel housings with integral front engine mounts, (remember, they were mounted backwards!) and were available in opposite rotating pairs. Their primary downfall was that they were made for raw water cooling, so today, any remaining engines you might find are seriously corroded inside by salt water. There is a lot of parts interchangeability between the marine engines and truck engines, and many improvements can be made to a truck engine using marine parts, just as long as you are certain you understand how the marine version works. Marine engines were generally propped to operate at a steady 2950-3000 rpm under load, with a Zenith or equivalent one barrel carburetor, centrifugal distributor advance, and water cooled exhaust manifolds. HP ratings varied, but both the shorter block and the longer block were available as marine versions. There are still a lot of NOS parts around for these. I hope this helped a bit!