Glastron repower project

[ChryslerIdiot]

Hello All,

I am working on a repowering my 20 foot Glastron runabout. The boat was given to me as it needed a lot of work that was way over the previous owners head. When I got it, the boat had the skeleton of a Mercruiser 4.3 sitting in-front of an Alpha One. I scrapped the remainders of the engine, sold the Alpha and got a Bravo One with 1.81 gears. That's not a ratio I've ever seen in a Bravo One, but it's common in the Bravo Two.

In place of the 4.3, I built a 512 CI stroked Chrysler big block. The engine make 423 HP and 486 pound feet on the dyno. My question is this, can I stick with the low gears in the out-drive and run a rather large prop? Something like the Mercury Bravo I prop at 32 pitch? The wiring and everything is complete, I'm ready for lake testing and tuning. Any advice would be much appreciated as this is my first foray into high performance that doesn't involve black top or concrete.

Thanks!

 

[Sea Rider]

Welcome to Iboats,

I'd guess that as long any brand/type, pitch prop achieves for OB to rev between wot rpm factory range as usually loaded, will be fine. But middle to max wot rpm is preferred.

Check a Prop Selector to dial a prop as a prop starter...

Happy Boating

 

[ChryslerIdiot]

Thanks for the advice and the welcome. The engine was designed for 7500 RPM and I've set the rev limiter at 6350 just for some comfort area. I stopped by the local marina today and they offered to let me try a 30 pitch Mercury Bravo I prop. Should be a good place to start.

Thanks Again.

 

[Sea Rider]

Yep, can go from there fine tunning pitch if in need to do so. Will ne good to dial a prop that revs OB to max wot rpm range of 7500, for that will need to set rev limiter free. When there, can throttle at the rpm you fell most confy with.

Happy Boating

 

[Bondo]

I built a 512 CI stroked Chrysler big block. The engine make 423 HP and 486 pound feet on the dyno.
The engine was designed for 7500 RPM and I've set the rev limiter at 6350 just for some comfort area.

Ayuh,...... Welcome Aboard,... I'm gonna be off-topic, But,....

Just how big is the cam in this motor,..??
Are you familiar with Marine motors, Vs: Hot Rod motors,..??
What are you usin' for exhaust for this motor,..??
Lastly,... How'd you marry up the Chrysler motor to the Bravo which has always been married to Chevys,..??