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  1. Texasmark

    1981 Mercury 7.5 2 stroke

    Smaller engines probably so, with only 2 cylinders. On larger engines a thermostat forces cooling water over the top of the top cylinders. Without the stat, they can overheat where there is no cooling water at the top as I read herein and what makes sense. Same thing on a car/truck/tractor...
  2. Texasmark

    1981 Mercury 7.5 2 stroke

    That wouldn't hurt. Pour 2 oz per gallon of Sea Foam (available everywhere) into the tank and then put in your normal fuel-TC-W3 oil 50:1 ratio. Run it for an hour if you can and let it sit over night or more. If you run it in a barrel, just remember that combustion temps are in the water...
  3. Texasmark

    Advice needed on 12'-14' jon boat purchase.

    I had a Toyota, the small sized truck before they made the full size...forget the name. Made the rack from the tailgate to the front of the bed out of electrical steel conduit.....scraps from dumpsters I welded (learned how to weld) together. I would drag the 10' boat up to the rear of the...
  4. Texasmark

    Might be dipping my toes back into boating

    At early 70's I too thought I was through boating having had a boat before I had a car and building one as a teenager. About 7 years later I realized I made a mistake and got back in. Got a bigger boat, smoother riding more whoopie.
  5. Texasmark

    Advice needed on 12'-14' jon boat purchase.

    That rig looks like my Lake John, wide and high sides.....great boat. Being aluminum and wide and flat bottomed, that 25 ought to push her along at 30 or so. Nice rig.
  6. Texasmark

    1981 Mercury 7.5 2 stroke

    I had a mid 70's 7,5 and never had to go into it, so I can't advise on that. For the 3 and 4 cylinder engines, the manual states that one should expect problems if cranking compression (about 200 RPM) was less than 120 PSI. I don't know why the smaller engines would be lower compression by...
  7. Texasmark

    Advice needed on 12'-14' jon boat purchase.

    My last John was a Lowe Lake John model. I built a top rack for my Toyota PU so that I could slide it up on the rack over the top of the PU working alone and could go places where a trailer wouldn't be convenient. It got banged around and this and that. Looked like new when I gave it to one...
  8. Texasmark

    Advice needed on 12'-14' jon boat purchase.

    You are probably good with any of these mfgrs. They have stood the test of time. Welded boats have become popular and I have had a couple for years/decades and the welds are good as gold.
  9. Texasmark

    2012 40 HP 3 Cylinder EFI Lower Unit Clutch Dog/Cross Pin Assy

    The shift cam that puts pressure on the pointed cam follower on front of the prop shaft is in the smallest radius position (least force) in the F position allowing the spring to extend the most and force the clutch dog to rest in the rear of the F gear. N is the medium radius and pushes the cam...
  10. Texasmark

    STAINLESS OR NOT

    I bought a new 18' Caravelle tri hull in 1972 with a 125 Johnson, factory aluminum prop. In 1973 the SST came out and since I dinged the alum almost every time I took the boat out I spent the $185 for the SST as I previously stated. One of my better decisions in life. Sometime later our work...
  11. Texasmark

    Performance expectations for a smaller boat??

    Round chine, deflection rails along the chine tells you that it rides in the water and the rails are to deflect the spray coming up. A lot of stuff in that boat. If you just want 20 you probably will make it. Looks like it has been well cared for and not a lot of usage. We both know what...
  12. Texasmark

    Recommended DVA meter or DVA adapter for a Fluke digital meter

    You can make one: 600V 1 amp. diode, wired with the anode to the signal source and cathode to the output wire (where you attach your + meter lead) which also contains a capacitor and bleed resistor. Select a meter DC range that exceeds the value of the voltage you will be measuring. Values...
  13. Texasmark

    Dog clutch position

    The "overrun clutch"sloped area.....that mates to the overrun clutch slope on the rear of F gear is on the correct end of the prop shaft. The other end has vertical walls to mate with the vertical walls on the rear of the R gear because there is no "overrun clutch" function on R...
  14. Texasmark

    Is this going to be a problem?

    Other thing is the diameter and inner shape of the thrust washer. You ought to be able to go to a well entrinched boat dealer with a wall full of used props and a box full of thrust washers and find a thrust washer that correctly fits your new prop to your propshaft. If you look at the...
  15. Texasmark

    Performance expectations for a smaller boat??

    Not 25 MPH with that load....by yourself I'd agree. Part of the equation is also the shape of the hull.....rounded chines like Alumacraft used to use or hard chine and especially a hard "reversed" chine makes a lot of difference in getting the hull up and out of the water to reduce drag and...
  16. Texasmark

    Thermostat closing position

    On what comes out when, oil floats on water. Lot of farmers drain off their condensation by opening the drain plug and watching the water come out and when oil starts coming out they plug it back in and top off the crankcase with the appropriate oil. A 2012 Mercury, even if used in salt water...
  17. Texasmark

    Thermostat closing position

    I know nothing about your engine except that the water and oil circuits don't touch each other. Your water in the oil is probably condensation from humid areas and temperature changes. It happens in farm equipment all the time. Possibly the engine design needs "some" cooling under all...
  18. Texasmark

    Need to reduce ventilation

    By angling the blades to the rear you provide a semi-horizontal surface, not provided by props without it. Trim allows you to tilt that horizontal surface such that water pressure on the blades cause an uplifting motion for the bow of the boat.....like Ailerons on an aircraft. My first...
  19. Texasmark

    STAINLESS OR NOT

    On the "Rude SST" if you missed it.....posted about this somewhere before. I bought a new rig in 1972, 18' Caravelle with a 125 Johnson. OEM prop was aluminum. The local lake was a fresh fill with lots of saplings. We'd go out on usually Sunday afternoon. Monday during my noon break, I...
  20. Texasmark

    Need to reduce ventilation

    The Hustler has "rake", bending back of blades from the root. This is your source of bow lift.
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