Trojan Boat Forum

I am gonna put this engine in during the weekend and need to get some input. I think if I prop her right and stay off the gas that I will be ok. Any expericence with a 454 in an F-25 would be a great help.

Torque moves mass and a big block 454 correctly set up can make alot of torque. I upgraded from a 305 to a 350 in my F-26 and changed the prop pitch accordingly. The end result was roughly the same top end with much shorter planing time/distance and a little better fuel economy because the engine doesn't work as hard as the 305 did.

Upgrading to a big block may be a little more difficult due to it's physical size. While the bolt patterns are the same for the motor mounts and transmission, this engine is wider and taller. In order to close the hatch on your engine bay, you may have to sit the engine lower between the stringers. This will create shaft alignment issues that will have to be adressed. In a large bay, moving the engine down and back will allow you to keep the same alignment that you have now but the F-25 has a relatively small bay which means this move may not be possible.

As far as the prop goes, if you fill out the on line form at Michigan Wheel which asks for LWL,LOA, horspower, beam, etc. , they can determine the correct prop for your application.

Hope This Helps
Paul
Cruise Control

I see your point. I would love to go with the 350, but I will have to wait for the tech to build one. Which sux. Plus, I really don't want a rebuilt engine. I figure if I get this engine and not happy with it, I can always trade it for a 350. I mean this engine is clean and preforms FLAWLESSLY. The tech and I are good friends and I give him alot of old blocks and parts that my uncle who owns a salvage yard gives me. I traded him my 305 engine and $800.00 cash. Look at the cost of 454s and I think that is a deal. If I have a big problem with the shaft alignment, then I will have to build a 350. I really hope this 454 will work for me. I will try it and if all else fails I will have to take a different path. Thanks!!!

as torque is king in a boat. What carb will you use? Get a marine Quadrajet if you can (I know that others willdiasgree, as they require a bit of setup, but just buy a carb kit and you're done.). Its ais a "spread-bore", menain the primary bores are dinky (fuel efficent!) and the secondaries are huge (when you want to show off a bit). Holley, Carter AFBs, etc. are "squaure bore" meaning all four barrels are the same size. Easier to setup, but don't gain effiecney at low speeds, and huge power jump when the secondaries kick in.

On my 25' Chapparal 454 I/O boat, I get 4mpg @ 21 knots, and a 51mph top end. I'm moving up 2 inchs in pitch and will do even better!

A Small Block would be struggling, an will use more fuel overall.

BoatDiesel.com ($25/year) has a great Prop Calculator. taht works for any hull/engine type. It has proven to be very accurate compared to real life results on dozens of boats I have worked with or owned (4 currently).

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if you decide to get rid of the 454, shoot me an email.