Thanks Thanks:  0
Likes Likes:  0
Page 1 of 11 1234567891011 LastLast
Results 1 to 10 of 104

Thread: Need the facts (From the OMC xperts)

  1. #1
    Team Member
    Join Date
    Feb 2007
    Posts
    44
    Post Thanks / Like

    Default Need the facts (From the OMC xperts)

    Ok, this pertains to a '76 135 Evinrude, all stock, in remarkable condition for it's age. Former owner was the proverbial old man who took it fishin on Sundays. Kept records of all the service, etc. It weighs 271 lbs, according to the specs.

    The boat...is going to require some explanation.
    The boat that this will be used on is a 17' Ranger Bassboat (1776 Super A). Up until 1976, Ranger made some pretty cheesy bassboats, by todays standards. To commemorate the bicentennial, and because Ranger was sponsoring a major bass tournament that year, they introduced a new model, the Super-A. The designer of the hull was a man from Tennesee by the name of Darris Allison.....
    The hull is identical to the Allison offerings of the late 70's, but the Allison models (of course) kept the extras to a minimum to conserve weight. I have De-Rangered the boat, by removing all the carpets, chrome doo-dads, the rod locker. New stringers and deck using Marine Plywood, S-glass and Epoxy, moved the seat and steering closer to the center. The lids for the compartments weighed 80lbs alone! I have not weighed it yet, but I suspect it weighs around 500 bare of seats, gas, batteries, motor. Oh yes, I put in all new 4lb flotation throughout, except for the bilge that runs through the centerline. I spent 4 months of free time on the structural, and would trust my life to this boat.
    I still have cosmetic things to do when the weather warms up. I do plan on having a trolling motor on the bow, and will make the livewells usable if needed.

    What I want to do is make this a one-man fishing boat that has some 'giddy-up'. Id like to use the 135, but others have cast doubts that it will perform to my expectations, and suggested that I 'hang a 225 merc on the back' if I want performance, and that it'd be a miracle for this old OMC v4 to do much better than 55. Granted, I didnt say what kind of boat I was using, so they may have a preconcieved notion of a 20', heavy bassboat that Ranger is typically known for...

    What I plan to do is see where Im at rpm-wise with the stock prop, get familiar with the handling, and then maybe some of you guys can help me put together a game plan for the best approach.


    But I do have one burning question: Has anyone ever adapted a sportmaster (Or similar perf. lower unit) to a stock v4 x-flow?

    Is anyone aware of any books written about outboard motor engineering? The science/art of gear ratio selection, prop pitch, and the many other variables involved?

    Its late, but my other questions will have to wait....

    Remember, just the facts!

  2. #2
    Team Member JohnsonM50's Avatar
    Join Date
    Apr 2005
    Location
    Jersey
    Posts
    602
    Post Thanks / Like

    Default

    As far as the hull goes your on the right track, floatation up in the gunwales if possible is good. Is the keel arrow straight? You could try a speed coat on the aft of the bottom. A hydrolic transome jack with trim / tilt and a performance prop will maximize the 135.

  3. #3
    Sam Cullis Mark75H's Avatar
    Join Date
    Nov 2004
    Location
    Annapolis, MD USA
    Posts
    1,795
    Post Thanks / Like

    Default

    If you are talking about the Merc Speedmaster, OMC made racing versions of the V-4 and their own racing lower units for them. It would be less work to find one that just bolt up instead of adapting a Merc Speedmaster. As far as the Sportmaster, no one that I know of has adapted a Sportmaster or Torquemaster to a V-4. It is truely less work to run a V-6 and the results are more or less guaranteed vs not.

    More directly to the pure racing lower units is that they do NOT INCREASE SPEED by themselves and then ONLY IF YOU ARE ALREADY running 80 mph or above on a very very light boat; something well under 800 pounds total weight. In connection with this, props were not made for speeds less than 80 mph for any of the racing lower units and you would have to have one custom made at $400 to $600; the 80 mph props cannot be repitched to run 60 mph.

    More directly addressing your rig, the larger diameter stock prop will work much better with the size and weight of your boat. Generally the smaller diameter lower unit and prop you use the faster you can go - providing they still produce enough thrust volume for your rig. Larger heavier boats need larger props which have to run slower RPM because the blade tip speed may not exceed the speed that causes water pressure behind the blade to drop low enough to boil - true "cavitiation" (vs ventilation which is something different). The larger the diameter of the prop, the higher the blade tip speed is in MPH at the same RPM

    No insult intended, but I would be surprized if your boat is quite as light as you hope. In most communities there is either a grain scale or a scrap yard scale where you could weigh your trailer alone and again with the boat on it to confirm the weight. Don't forget that you and the motor will probably weigh close to 500 pounds unless you are very small and 10 gallons of gas weighs 70 pounds. That means the boat would have to weigh 300 pounds or less to benefit from a racing type lower unit.
    Since 1925, about 150 different racing outboards have been made.


  4. #4
    Team Member Bill Gohr's Avatar
    Join Date
    Sep 2006
    Posts
    198
    Post Thanks / Like

    Default

    Well, there is a chance that that boat would get down to 500lbs, but that would be empty, without you or a fishing pole, so keep that in mind.
    There was test reports back them for that boat, probably with a 115 merc on it as shown in the pic. Just do a comparison of that with the 135 on it. The 76 135 is a pretty stout motor, I would rate it as 3rd strongest of all the old V4's, stock, the gearcase will hold you back, it wasn't designed for speed, very blunt in the front. Normally, I wouldn't tell you to put a nosecone on it till you were over 75mph, but on that old case I would do it anyway, no need to change it, just reshape it.
    The post 79' gearcases were much better and I have run them close to 80 with out a cone but that was pushing it. The 135 should get you into the high 60's or 70's, it has a taller gear ratio than the later V4's, find yourself a 14X22 Chopper and have it rehubbed and go from there.
    Don't be afraid to spin it over 6K we ran them there all the time.

  5. #5
    lil timmy tthibodaux's Avatar
    Join Date
    Apr 2006
    Location
    Beaumont Texas
    Posts
    113
    Post Thanks / Like

    Default Turn it up.

    6000 rpm, you can turn that dude way more than that. I have turned mine 7100(all day) BUT it's rpm curve seems to be at about 6700. Anything after that and it's not pullin anymore just spinnin. Mine runs best on the HydroStream at about 6400.
    THIBODAUX RACING... Timmy Thibodaux

  6. #6
    Team Member Bill Gohr's Avatar
    Join Date
    Sep 2006
    Posts
    198
    Post Thanks / Like

    Default

    Oh without a doubt, you can spin them where ever you want, but keep in mind his motor has lower ports than yours. I was giving him a safe rpm for a 31 year old motor, when I ran my modified 140 on my Vector I ran it at 7700rpm.

  7. #7
    lil timmy tthibodaux's Avatar
    Join Date
    Apr 2006
    Location
    Beaumont Texas
    Posts
    113
    Post Thanks / Like

    Default I agree.

    Quote Originally Posted by Bill Gohr View Post
    Oh without a doubt, you can spin them where ever you want, but keep in mind his motor has lower ports than yours. I was giving him a safe rpm for a 31 year old motor, when I ran my modified 140 on my Vector I ran it at 7700rpm.
    Your rite. Man they sure sound SWEET turnin over about 6500.
    THIBODAUX RACING... Timmy Thibodaux

  8. #8
    Team Member
    Join Date
    Feb 2007
    Posts
    44
    Post Thanks / Like

    Default

    Quote Originally Posted by JohnsonM50 View Post
    As far as the hull goes your on the right track, floatation up in the gunwales if possible is good. Is the keel arrow straight? You could try a speed coat on the aft of the bottom. A hydrolic transome jack with trim / tilt and a performance prop will maximize the 135.
    I replaced all the foam in the floor, there is already foam under the gunwales all the way around, including 2 massive glass-enclosed sections of foam on each side of the boat that are about 5ft, which I left intact. I suspect it is 2lb foam, because the foam I used is much more substantial.

    Ive got power trim/tilt, but have to manually raise and lower the height.

  9. #9
    Team Member JohnsonM50's Avatar
    Join Date
    Apr 2005
    Location
    Jersey
    Posts
    602
    Post Thanks / Like

    Default

    Quote Originally Posted by Charles Salsman View Post
    I replaced all the foam in the floor, there is already foam under the gunwales all the way around, including 2 massive glass-enclosed sections of foam on each side of the boat that are about 5ft, which I left intact. I suspect it is 2lb foam, because the foam I used is much more substantial.

    Ive got power trim/tilt, but have to manually raise and lower the height.
    I mentioned the floatation because it was part of your posting, when its all on the bottom - and if your misfortunate to flip, the boat would favor being wetside up with little chance of bailing. Its cool like you have it.
    I hitched a ride on a speedboat that had a jackplate It, used with the trim tilt really gave the boat a kick in the ahhhhh.. both low for takeoff then raised for speed. Ive seen them in Overtons if your interested [maybe somebody knows better] That would also give you a 5 inch standoff.

  10. #10
    Team Member
    Join Date
    Feb 2007
    Posts
    44
    Post Thanks / Like

    Default

    Quote Originally Posted by Mark75H View Post
    If you are talking about the Merc Speedmaster, OMC made racing versions of the V-4 and their own racing lower units for them. It would be less work to find one that just bolt up instead of adapting a Merc Speedmaster.

    Quote Originally Posted by Mark75H View Post
    No insult intended, but I would be surprized if your boat is quite as light as you hope.

    No use me speculating until I weigh it. I can pick up the *** end (without the motor on of course) off of the trailer enough to shift it. I shouldve done that when I had the motor off and the boat suspended from the rafters.

    Im just trying to find out what all my options are. I saw that there were aftermarket hp gearcases for those motors, not racing gearcases, but better ones. I think that the gearcase on the 135 is the same as the ones used on the 200hp, or the Stern-Drive units. Its huge.

Thread Information

Users Browsing this Thread

There are currently 2 users browsing this thread. (0 members and 2 guests)

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •