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newtojets
03-30-2013, 10:07 AM
ok so last year when i pulled the motor from my boat . I noticed that the flywheel was huge! Then when i pulled the motor from the donor boat, it had the same heavy ass flywheel. my question is why???? if were trying to make horse power that needs to go. i had the idea of shaving off some weight from one of the flywheels, good or bad idea, has anyone tryed this???? what happened??? i do know why one has a heavy flywheel for a truck, and the like . but a boat???

"THE ADVOCATE"
03-30-2013, 11:22 AM
I run a flex plate as do lots of other guys!

David
03-30-2013, 11:42 AM
I run a flex plate as do lots of other guys!
Yep... Mine too...

newtojets
03-30-2013, 11:49 AM
So you guys run a flex plate instead of a flywheel????

White Lightning
03-30-2013, 12:10 PM
I run a flex plate as do lots of other guys!

X2
Rob

White Lightning
03-30-2013, 12:11 PM
So you guys run a flex plate instead of a flywheel????

Yep.
Rob

alek72us
03-30-2013, 12:26 PM
Good question. flywheel is for a clutch and are heavy. in the boats its pretty much there just for the starter? a flywheel is about a 1/2" wider that a flex plate will that be a problem? I wonder if I could do this on my half-a-whacker?

wolfie
03-30-2013, 12:41 PM
So you guys run a flex plate instead of a flywheel????

x3 I've seen some pictures of flywheels that have come apart. Not pretty.

White Lightning
03-30-2013, 12:43 PM
Good question. flywheel is for a clutch and are heavy. in the boats its pretty much there just for the starter? a flywheel is about a 1/2" wider that a flex plate will that be a problem? I wonder if I could do this on my half-a-whacker?

Yes, where you need the inertia (that a flywheel has) to facilitate getting an object moving a flywheel comes into play. A Jet is like moving a car with an automatic transmission that has a torque converter, the jet 'slips' like the converter and lets the engine be in its torque range and remain there until the object matches its speed. Which ever you use, a flywheel or a flex plate, they have to be the same diameter to match the starter that you have. Most manufacturers have a couple of different diameter flywheel/flex plate/starter set ups to choose from so you need to know what diameter you're dealing with.
Running a heavier flywheel will take the engine longer to come up to RPM. If you have a situation where you NEED to slow down your RPM, say like for a more controlled hole shot, then it's the way to go. Otherwise run the lighter flex plate.
Rob

whitehairdude
03-31-2013, 07:12 PM
dang, that brings up a good question for me. My donor motor (455 olds) has a flexplate but the 455 in the glastron had a flywheel! Will changing it to the flexplate mess with the stickout length of the coupler? Im pretty sure it'll move it towards the engine by maybe a 1/4-1/2 inch due to the thickness of the flywheel verses the flexplate! I can see where the flexplate will let the engine rev quicker, so that sounds like a good thing to me. Why would the factory put a flywheel on it? Gotta be a reason!! It weighs more and cost more so what gives?? Yall got me to thinking on this now, I haven't put the motor back in the boat yet....What to do!!

whitehairdude
03-31-2013, 07:28 PM
Dang, had to run out to the scrap metal trailer and dig deep to find that booger!! now I bet I have to dig and find the shorter bolts for it and prolly buy new/shorter bolts for the yoke too!! That yoke is a PITA to get on and off!!

newtojets
03-31-2013, 07:42 PM
may have to run shorter bolts , may not???? it is possible that it will move the yoke not the engine , i have a slip yoke and a 1/2 of an inch is not going to break the bank here. as far as help the engine oh yah , its a big deal. heavy flywheels are used for trucks . it should not only make it spin up faster but free up power.