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  1. jimmbo

    Johnson Motor identification help needed

    That looks like a 28 hp cylinder head, a 33 hp head would look a lot different From the 1963 brochure, some info
  2. jimmbo

    90hp vs 115hp

    In 1984, I replaced a crank rated(1978) 90 hp Mercury, with a prop rated(1984) 115 mercury. The boat went from 38mph, to 49mph. If it had been a crankshaft rated to crankshaft rated motor, or a prop shaft rated to prop shaft motor, the increase would have been about 5 mph
  3. jimmbo

    1990 Evinrude 20 HP convert to 25 HP (Model # E20CRESB)

    A lot of work/hassle to maybe gain 1 - 3 mph We had a 79 25, and an 80 35, on the same hull. there was only 2 - 3 mph difference, the 25 did idle down a bit better and was less jumpy at off idle. Granted those years they had different midsections and gearcases.
  4. jimmbo

    2 bunks vs 4 bunks

    Here's how mine are spaced. Boat's not perfectly centered, but it has never been an issue. Sometimes I get a bit better, other times it is off on the other direction. As for tippyness, it sits rock solid and stable. This year, I have had it 17 years. It has a 5.7 V8 in there Without the...
  5. jimmbo

    2 bunks vs 4 bunks

    It is easier to set up a 2 bunk trailer than a 4 bunk, but some dealers can still bungle it. However it does look like the bunks on your trailer are way too far apart. Moving them closer together will help the self centering Take it back to the Dealer and tell them to set it up better. I really...
  6. jimmbo

    What effect does motor height have on attitude (bow lift, porpoising, etc)?

    Here are Mercury's recommendations. The only time they recommend putting the AV Plate below the hull, is on Heavy barges. Other Outboard makers have similar Philosophies
  7. jimmbo

    1987 Johnson 90 - Block Rebuild Upgrade?

    It is possible to turn a 99.6 cubic inch 90 into a 110, 112, 115 or even a 140. a bit of machining, and some parts and it is a done deal. It is also possible to get more than 160 hp out of that Block, with some serious machining and modifications.However it will not be a very good Recreational...
  8. jimmbo

    45hp Chrysler Prop / Top speed mystery

    Looking in the 1974 Chrysler Brochure. Your engine has a gear ratio of 13:21 or 0.619. 45hp@4750 rpm A WOT range of 4400 - 5100 rpm 3 different ignition systems: Magnapower; Battery; Magneto 4650 rpm with the 11.5" would be 28mph with 10% slip and 26.8 mph with 15% 4440 rpm with the 12.5" would...
  9. jimmbo

    Propping for skiing

    Is the timing set to spec? Drilling the prop is an option, but it must be done with care with regard to location and size.
  10. jimmbo

    Suggestions for a 1978 TOP 900 coil

    Can the spark jump a 7/16" gap? On every plug wire? Are the carbs dribbling gas out of the vents when running? Are they all fully closed when at idle? Are the mixture screws all set for best idle. "Carbs cleaned before I got it" could mean last week or 5 yrs ago. I know what I call 'cleaning a...
  11. jimmbo

    Anyone know vintage merc 1000's

    i doubt the lower on the BP lower units will easily swap to a regular motor
  12. jimmbo

    What year is this Crestliner?

    This is from a 1961 Crestliner Brochure
  13. jimmbo

    Seeking information about older 2-stroke Mercury outboards

    The 49.7 block was introduced in 72 as a 65hp, in 73 they changed the Block(same displacement, but added a one inch hole in the piston skirt, which basically added another transfer passage between the Crankcase and Combustion Chamber. These Power Port and Power Port Pistons were added to the...
  14. jimmbo

    OMC prop choice

    It might affect the numbers. Which way? It could go either way Was the prop bent like that before you used it? If not. the numbers you gave were pre or post damage? Get the prop repaired,or get another 14 X 18, then see what it does, at least you will have a more reliable starting point...
  15. jimmbo

    OMC prop choice

    You're overrevving, provided the tach is accurate. Your engine has a WOT range of 3800 - 4200 rpm. You need to add pitch to get the rpms into that range. Whether you get more speed is unknown. Adding pitch means adding load, resulting in a lower RPM, so there might not be a speed increase. The...
  16. jimmbo

    Boat goes on sideways

    They are supposed to support the keel. A lot of trailers that use keel rollers don't have many rollers/supports to the sides
  17. jimmbo

    1983 90hp won’t idle

    If that doesn't fix it, then the Serious Troubleshooting can commence The idle speed adjustment is nowhere near the carbs, it is on the long Linkage arm/lever on the Port side of the engine, Word of caution, any time you fiddle with the idle speed, you will probably need to adjust/change the...
  18. jimmbo

    What trailer will I need?

    Years ago, the trailers were narrower, with smaller tires, the boats were just carried above the fenders Our 14 ft with a 70" beam on a late 50s/early 60s trailer This one had a 77 in beam, but the trailer was wider and the boat did fit between the fenders, but it was very close, though...
  19. jimmbo

    Gateway errors

    Site is acting weird. It appears I am in, but then Server Errors appear saying it at iboats end. I reload, and it is up, though in the upper right when my name should is blank, but I am logged in as I can post. Rebooting the computer offered no change. Any big Electrical Storms anywhere on the...
  20. jimmbo

    Need some advice on a possible prop purchase.

    In Stainless, an Enertia would be a very good choice on your combo. It has great Acceleration, and can give a higher top speed as well. It has a Tenacious Grip on the Water and will actually lift the boat Vertically out of the water. My Avatar shows it. The drive is not over trimmed
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