SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: bbfsouthwind on October 06, 2013, 06:39:13 PM
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I am in the process of rigging my southwind v bottom, I have a 460 ford with motor plates and 2 1/2" rails on the stringers mounted 1/4" from the top. I also have the pump sitting in the boat, the centerline of the pump shaft and crankshaft are 5" apart with the engine being higher. I have 6" of oil pan clearance, should I lower the rails on the stringers or trim the motor plates to lower the engine? I can only trim 3" from the rear plate before I run into the starter cutout.
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I am in the process of rigging my southwind v bottom, I have a 460 ford with motor plates and 2 1/2" rails on the stringers mounted 1/4" from the top. I also have the pump sitting in the boat, the centerline of the pump shaft and crankshaft are 5" apart with the engine being higher. I have 6" of oil pan clearance, should I lower the rails on the stringers or trim the motor plates to lower the engine? I can only trim 3" from the rear plate before I run into the starter cutout.
Trim the motor plates to fit. Make sure you have enough angle in the drive line as well. You don't want it just straight, its its straight it will blow it apart.
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The pros use a mock up block that connects to the jet with a pipe. From there you can make the measurements and and make the plates. In your case trimming is just fine.
Some examples below
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi187.photobucket.com%2Falbums%2Fx306%2Fbusby061%2F062009010.jpg&hash=c730e810a0a26bb0119a693249dcc826499daf3a) (http://s187.photobucket.com/user/busby061/media/062009010.jpg.html)
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2F2010%2520misc%2Flylemiller%2FDSC00481.jpg&hash=767dcd307efba91675a3268d92dfd28d2d6b8089)
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The pump is set at 4* so I am going to make the motor match the 4* angle. How close do I want to get the center lines of the crank and jet pump shaft? I know you want some mis-alignment to keep the u joints loaded and spinning.
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you want the engine and pump shaft to be set to the same angle... so parallel with each other. but you want a good 2-3* in the driveshaft. keep in mind this 2-3* can be negative (downward) to get your engine lower in the boat. lower engine will always be better, lower center of gravity, etc. if your rails are angled aluminum you can always flip them to get more clearance if you're running out of room to trim your motor plates.
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.5 - 3 degrees in drive and as mentioned crank / pump shaft parallel.
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So I have the rear plate trimmed so that my oil pan has 1/2" clearance to the bottom and my crankshaft centerline is 3/8 lower than the pump shaft centerline. Is this correct? I have the front plate trimmed but I have 6.2* of angle on the engine and I need to trim it some
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Your engine crankshaft should be parallel to pump shaft...the angle or offset should only be in the drive line/drive shaft. .5 - 3 is all you need in the drive. Find the parallel then move motor up or down...measure measure measure