@Texasmark
What size boat did you use to waterski behind with the 18?
What size boat did you use to waterski behind with the 18?
I agree, but I don't have money for brand new boat or long shaft motor. I really would like a larger motor but I can always just use short shafts right?Seems a shame to hack down the transom on a boat rated for75+hp to accomodate an 18hp motor....
I'm in maine btw @raceroneFind the 5" extension kit.---They are not hard to find !----Your location ?----Find a kit at the local meet for the ----aomci-----Or find one on the aomci----website !
Yeah, I'm gonna check my local boat yards.These motors were essentially the same for near 20 years.-----Lots of used parts / kits available from collectors I think.
That's a good response and I agree not just on the not hacking comment, but if it's rated for 75 the 18 will be a dog.....get another engine like a 50 or so......with a 20" leg.Seems a shame to hack down the transom on a boat rated for75+hp to accomodate an 18hp motor....
From previous photos it appeared that you only needed to lower the engine 2-3 inches to get the av plate even with the hull bottom, but you're saying you lowered the engine 5"? Now I have no idea of where your av plate is in relation to the hull bottom, and that is THE most important factor in regards to engine performance. But one thing seems obvious to me. Now that the prop is fully below the water line you need to get the proper pitch prop to allow your engine to reach the max recommended rpm at wot. But don't even think about prop pitch until you have the engine at the proper mounting height. Another photo like the first one you posted would help so we can see things as they are now.
I've seen the same motor on similar 14ft boats do about 20-25mph. Apparently people have used water skis behind these motors. Mine is maxing out really really low. I don't have exact measurements but I'd say between 2k-3k rpms. It just gets on plane and then won't speed up. With 3 people my tops is like 5mph. I've gone over everything but compression test. Think that's next?The height looks pretty good. Now you just need to find the right pitch prop to allow the engine to reach its wot max rpm, which I think is 4000-5000 rpm. But if that boat is rated for a 75 hp engine then you'll be lucky to even get it to plane with an 18 hp. It will surprise the heck out of me if you can even reach 20 mph.
Yeah I understand that. When its Just myself in the boat, the water is passing about a 1/4 inch above the av plate. That's at around half throttle 2500 or so rpms barely on plane. But that's as fast as it will go.If you have already modified the transom height, with deck load well distributed report at which lower leg height is the water flow paasing by, is it passing above the upper water plate, under it or towards the lower AV plate, for that must pull your head side of motor to check that out, no wild guessing nor wild assumptions here. If you sit the motor at a certain transom height for th AV plate to face or be even with the hull's bottom then you won't care at all at which lower leg height is the water flow passing by which it's of extreme importance as boats doesn't float same.
If the combo it's impossible to plane will need to install a less pitch prop to make it plane in order to check that out, boatig fun starts when the motor run towards its max wot rpm range while lightly loaded, say max 2 souls onboard, the issue is that being an oldie motor wil probaly have very few less pitch props to choose and go for. If not will have to content yourself achieving just fast displacement boring speeds....
Happy Boating
Yeah I understand that. When its Just myself in the boat, the water is passing about a 1/4 inch above the av plate. That's at around half throttle 2500 or so rpms barely on plane. But that's as fast as it will go.
Runs strong up to about 2500rpms (not exact)but it won't go past that. While pushing me in boat. In a barrel and in reverse it will hit around 5000rpms.Can you measure the gap distance in centimeters between both lower leg's plates. That lower leg must have at least a 3 inches gap if not more in between both plates. Is the motor running strong throughout the whole throttle range ? if so that motor needs an urgent prop swap to at least a niner or less prop pitch to plane faster with 2 up.
Happy Boting