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Repowering from Hercules

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endless summer
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Joined: Sun Dec 14, 2014 8:35 pm

Repowering from Hercules

Post by endless summer » Wed Aug 29, 2018 11:23 pm

I have a 1955 30’ Capitan and I absolutely love it. It cruises the shoreline awesome, but when I want to get somewhere in a timely manner, Endless Summer just isn’t fast enough. I am getting estimates to swap my twin Herhcules / Chrismatics with new technology V8’s. I have a few questions:

What are the best or most common replacement motors?

What are typical costs of a conversion of this nature?

What are unique things that have to be considered?

Are the original motors / transmissions worth anything when I remove them? How much?

Assuming that the motors are running as good as 1955 motors were designed to, are there any “hotrodding techiques” that can be applied to the original motors to get more power from them? Headers, different carbs, etc...?

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Bilge Rat
Posts: 228
Joined: Thu Jul 16, 2015 4:02 pm

Re: Repowering from Hercules

Post by Bilge Rat » Thu Aug 30, 2018 10:08 am

A couple of thoughts on your questions:

What are the best or most common replacement motors? Crusader offers an excellent product/horsepower line up most with fuel inject and a great warranty IF installed by an authorized facility

What are unique things that have to be considered? The Chris-o-matics are electrically controlled and any modern set up will require a mechanical cable system for the clutches so the helm controls will have to change. Helm gauges will most likely have to change as well, at the very least the tachs. Prop size/pitch will have to change to match the new horsepower and WOT limits. Possibly, the engine beds will have to be modified/beefed up to handle the new engines and torque. If you go with fuel inject, fuel pump and gas tank plumbing will have to change. Additional horsepower will mean the exhaust pipes will have to be increased or converted to two pipes per engine. Maybe even the prop shaft sizes will need to increase with stuffing boxes and struts to match.

Are the original motors / transmissions worth anything when I remove them? How much? Probably, but a lot has to be taken into consideration; what engine model, straight or reduction transmissions, ever used in salt water, how many hours on them.

Assuming that the motors are running as good as 1955 motors were designed to, are there any “hotrodding techiques” that can be applied to the original motors to get more power from them? Headers, different carbs, etc...? Not really and any "gains" that might happen would probably cause other unintended results that may require addition tuning, driveline or structural modifications and $$$.

Cruiser owners on this site that have gone this route will have recommendations I'm sure.
Last edited by Bilge Rat on Thu Aug 30, 2018 1:43 pm, edited 3 times in total.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

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Bilge Rat
Posts: 228
Joined: Thu Jul 16, 2015 4:02 pm

Re: Repowering from Hercules

Post by Bilge Rat » Thu Aug 30, 2018 12:50 pm

I Googled your boat, a truly beautiful example!

Most people think of re-powering when the original engines are too far gone for a reasonable rebuild. What you are contemplating will take a high degree of engineering and understanding of physics and water hydraulics to implement correctly. Even then, expect a lot of tweaks and adjustments to get it dialed in like you want it. Prop selection will be critical for desired all around performance.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

davidvn
Posts: 63
Joined: Thu Sep 06, 2007 9:23 pm

Re: Repowering from Hercules

Post by davidvn » Fri Aug 31, 2018 2:14 am

You may want to consider a pair of beta diesels they’re lightweight smooth running and you can run the transmissions in either directions to get your Port and starboard engine. I don’t think you’ll find a huge difference in price From a gasoline engine although the correct diesel might be a bit more expensive but you will make up for it with Betterfuel consumption. I do not sell these engines but have made many recommendations as to the model and would be happy to give you my input. If you would like more information either here or on a PM please feel free to contact me. Good luck with your repower.

endless summer
Posts: 3
Joined: Sun Dec 14, 2014 8:35 pm

Re: Repowering from Hercules

Post by endless summer » Tue Sep 25, 2018 11:10 pm

Thanks for the feedback. I got the bids back this week to repower my Capitan with new V8s and after I picked myself up off the floor, I decided to tolerate my shoreline cruiser - at least for one more year. I still want to maximize what I have though.

I searched this site for a while and found one thing that I tried and it actually improved the performance of my motors. A few years ago, I had electronic points installed and they didn’t take the ballast resistor out the the coil circuit. I did that last week and my motors seem like they are much more powerful and now they top out at 2500 RPMs whereas before they would be around 2100. Using a speedometer app on my phone, I measured my speed at 17 MPH and it’s now pretty close to being acceptable. Next spring I will put new props on the boat hoping that the RPMs will get higher and closer to the maximum power band of these old motors. Hopefully, it will translate into a faster boat.

Any thoughts?

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