When I built the new motor for my Scimitar, I Installed a 4 1/2 pound flex-plate rather than the 47 pound flywheel to reduce weight and the motor would have a more rapid exceleration, I always wondered why they used a big heavy flywheel on the motors anyway, when it seemed to me that a flex-plate would be better, well, I quess I found out why.
Today I removed the motor to check it out and find out why it had a squeeking and vibration sometimes, not all the time, also I got another camshaft I think will help push the boat on up to 70 mph, the new cam should add another 25 to 35 hp, it's a roller 510/520 lift 292/300 duration, I'll still be running the 1.5 rocker arms so it will come out to 510/292 with a power range from 2200 to 5800 rpm.
I removed the flex-plate and found out where the vibration and squeeking was coming from, all the bolts were tight and there were no cracks in the flex-plate but the three little rubber vibration dampners that is squeezed between the coupler and the flywheel were all three gone and laying in the bell housing in pieces. When I had the coupler turned down to fit into the crank shaft it did not fit tight, the squeeking was created by the coupler rubbing against the in-side of the crankshaft when the drive was not trimmed strait through the U-Joints, causing the vibration and allowing little rubber bumpers to escape.
I have a new flywheel, 13 pounds lighter than the original that weighed 47 pounds, and I'll have to get a new coupler tomorrow because of the machine work I had done to the other one .... grrrrrr Another reason I was interested in removing the flex-plate was because the cam was kicking the drive gears and prop at idle in gear causing excessive wear on the drive gears, the new cam will be more radical and the 34 pound flywheel will reduce that kicking and wear.
