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Hi Guys. On my Grand Pa boat I was thinking of going to a 454. It now has a 350 Mag with Alpha 1 gen 2 drive. What would it take to go to a 454. No big H/P. 400 max. What you guys say? Thanks.
 

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If you drive it like a grampa, it will live, if not, it will be junk in short order. Also, don't over prop it (too much pitch), and it will live longer. With Alphas not bringing much on the used market, you might as well try it. Mercruiser tried it several years ago and had a lot of warrenty issues. Run a thru transom exhaust, as the Alpha exhaust thru the leg is too small for even a 350. We have done some 350/Alpha hop ups, and found that replacing the small risers with BigBlock units, and adding thru hull exhausts gives 4-7 mph gains on a 21-24 ft boat. A Comp 270 cam gives a healthy gain, as does an RPM Airgap intake and Edelbrock 750 carb. With those mods, you won't have the torque of the bigblock, but with the weight difference you will run as fast or faster, just at a higher rpm. I ran a 24 Daytona with an Alpha/350 combo a few years back (bought it cheap!) It ran 44 mph stock as purchased, I did the thru transom 4'' exhaust, Bigblock risers, airgap, 750 afb, and used a Comp 280 cam(a bit bumpy idle for most non-perf peeps). When propped for the new power, it ran 62-63 mph. It didn't holeshot like a 454, but gas mileage was great, and it did run over 60. When I finally blew up the drive, I installed a SternDrive Engineering unit and never hurt it again. The new buyer had a 434 built and it now runs over 75mph and still hasn't hurt the drive. Food for thought. TIMINATOR
 

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timinator stated some good information. Best bet would be to get the small block to perform better ie, exhaust(tru transom), intake, carb, and ignition and see where that gets you first. The drive will be much happier and live longer. Smaller prop and higher rpm will be what you want to make the drive last longer than putting a big torque monster in front of it. Good luck on the project.
 
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