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  1. #11

    Re: Cummins V8-300-M

    Quote Originally Posted by mstailey
    Sky Cheney,
    That would be the VT555M engine.
    Are you sure you're not thinking of the 504? I know they share the same stubby 5/16" plunger injectors, but the 903 has regular PT injectors. But I'm not an expert on Cum-a-parts, so you may be right. However I think it's a long way from the triple nickel to a 903 if we're talking cubic inches (I can assure you it's not horsepower).

  2. #12

    Re: Cummins V8-300-M

    As the new kid on the Hatteras Owners Dock, this is my introductory reply to a thread. The Cummins V8-300-M was the predecessor to the 903. As stated, it is the non turbo version of the VT8-370-M. Both of these engines were 785 cubes in displacement and both rated at 3000 RPM. At that time the Cummins 300 and the 8V53 were considered to be medium duty engines hence their high RPM. The Cummins 300 had over the 8V53 much quieter operation and better fuel consumption because of its 4 cycle nature. The Cummins engine was heavier than its DD counterpart and both were available with the Twin Disc 506 marine gears. The Cummins engine was also available with the Capitol gears. Longevity should be rougly the same and parts are expensive and sometimes difficult to locate for both. BTW, the Coast Guard never used the 785 cube engine. They started using Cummins engines in their patrol boats when the 903 came unto the market.

    Jim

  3. #13

    Re: Cummins V8-300-M

    I had one of those vt903 engines in a semi..and the only thing I would ever use one for now would be to {a} tie a rope to it.
    {b} throw it in the water
    {c} tie the other end to my cleat
    {d} go fishing!
    Jim

  4. #14

    Re: Cummins V8-300-M

    Quote Originally Posted by AquaNav77 View Post
    As the new kid on the Hatteras Owners Dock, this is my introductory reply to a thread. The Cummins V8-300-M was the predecessor to the 903. As stated, it is the non turbo version of the VT8-370-M. Both of these engines were 785 cubes in displacement and both rated at 3000 RPM. At that time the Cummins 300 and the 8V53 were considered to be medium duty engines hence their high RPM. The Cummins 300 had over the 8V53 much quieter operation and better fuel consumption because of its 4 cycle nature. The Cummins engine was heavier than its DD counterpart and both were available with the Twin Disc 506 marine gears. The Cummins engine was also available with the Capitol gears. Longevity should be rougly the same and parts are expensive and sometimes difficult to locate for both. BTW, the Coast Guard never used the 785 cube engine. They started using Cummins engines in their patrol boats when the 903 came unto the market.

    Jim
    I have a 1970 Hatt 53MY with the Cummins VT8-370-M engines and I believe the transmissions are the Capitol Gears variety. Do you know if there were certain Capitol Gears transmissions used? I can find no plate on the transmission and the only piece of paper around the boat says it is a Capitol Gears 12400, but I can't find any info saying they ever produced at 12400. Would love to lay my hands on a manual or even a list of quantities! BTW, my engines were rebuilt about 15 years ago and just keep chugging along. No issues so far. Touch wood.

  5. #15

    Re: Cummins V8-300-M

    Quote Originally Posted by hatterasboatguy View Post
    I had one of those vt903 engines in a semi..and the only thing I would ever use one for now would be to {a} tie a rope to it.
    {b} throw it in the water
    {c} tie the other end to my cleat
    {d} go fishing!
    Jim
    That was about all I heard of them in trucks as well. Main bearings every 30K miles. They didn't call them the 9-0- nuthin' for nothing. Marine and military applications seemed to fare better.

    Quick trivia. If anybody remembers the TV show Movin' On with Claude Akins playing Sonny Pruitt they had a Kenworth with a Cummins. The show only ran two seasons. In the first season you could see the big proud numbers on the valve covers whenever the hood of the truck was open, 903. The second season, the V-8 was gone and there was some variant of the venerable 855 in it's place. Apparently it didn't even hold up well enough for a TV show where the truck didn't actually have to do any real work.
    --- The poster formerly known as Scrod ---

    I want to live in Theory, everything works there.

    1970 36C375

  6. #16

    Re: Cummins V8-300-M

    The best advice anyone could give you regarding the eight cylinder Cummins engines is to run like the wind.
    Cummins knows how to build motors however they do not know how to build V-8 engines. I owned one in a truck the replacement parts were hideously expensive hideously hard to find and when you were done you still ended up with a heavy expensive to repair piece of junk. They are heavy they don’t have much horse power
    and they eat fuel like I eat turkey at Thanksgiving in other words don’t buy it.

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