bertram31.com

There is a listing for a Cummins 370 with ZF220 gears (1.2R...not sure exactly but I assume 1.2:1) Says he has 2 available and they are Brand new and bought from seaboard marine.
$25K each

They sure are pretty...


https://www.ebay.com/itm/144125684999?h ... Sw1Dhg-iHk

They are. I wonder if they will fit. I know the QSB's will but not sure those engines will.

Jason put them in Snipe. They are Cummins B 370's not the QSB series so I think they are good to go for anyone lookin for a repower

Yes frank only thing you would have to change is the aftercooler pipe turbo to aftercooler it will hit the engine box without modifications.
Or at least in my application.

Jason, you been a little quiet lately? How is snipe coming along?

The boats really gotta skoot along with those...

...almost twice the power of my 210's.



Funny 25k doesn't sound bad till you think...

hmm, I need two plus....


then the smile slowly fades a bit. But they would move boat along nicely. A friend has them in his 39 Carver Aft bubble boat and it goes. True very different boats but 31 to 39

They are a pretty good deal when considering the transmissions are included in the 25K The gear ratio is not what I'd want plus I want electric troll and shift which are pricey options. Another advantage is they are ready to be shipped not 6 to 8 weeks out! Disadvantage is the engines are 6 years old and no warranty.

A QSB 5.9 380 Recon is now 35K with no transmission. Depending your the gearbox options the ZF220A ranges from 4K to 8K.

The included transmission are 1.2:1. I dont know if that is a good combo for a 31 Bertram. You could use the stock strut but would only be swinging an 18" prop. I am no engineer but I do recall some talk of this on an older thread.

Any ratio will work but the props that go along with the combo may not be the best choice. I think most guys with Cummin 250hp to 330hp are using 1.5:1 transmission.

Taking advantage with the big prop is better from what I recall...but again I am no engineer

I was wondering if the gear ratio could be changed on the gears. I suspect it could but this is not in my wheelhouse.

Frank

On a 31 you can turn up to a 21 inch prop. Make up any difference with pitch and cup.

Tony Meola wrote: ↑Aug 7th, '21, 23:22 Frank

On a 31 you can turn up to a 21 inch prop. Make up any difference with pitch and cup.

Tony- on some 31’s you can turn up to a 21” prop. Some as others cannot.

My boat came through with 1:1 gas motors, 1-1\4” shafts and 15” wheels. This was the original low angle setup at 10° which was changed to the more traditional 15° angle you refer to that can handle larger wheels.

On mine I swapped gearbox’s, getting rid of the 1:1 for a slower turning shaft with 1-1/2:1. I tried 17” wheels…but noisy and even though 4 blade, not smooth. No hull burn, but was much better with 16” wheels…the largest I’d recommend with the original 10° setup.

Carl

That is a pretty small wheel for a diesel engine.

Tony Meola wrote: ↑Aug 8th, '21, 21:05 Carl

That is a pretty small wheel for a diesel engine.

I think 16" wheels would have been ok if going with high revving types of diesels, like Yanmar or Steyr. Not so great with the Cummins. What I was referring to is the tranny swap I did with the gas 440's. I went from 1:1 to 1-1/2:1 then went up in diameter and pitch for more economy and a smoother ride.

When converting to diesel I scrapped the little old struts, gave shafts away to a friend then made myself a pair of beefy SS struts to accept 21" wheels and stay at an 11deg down angle.

im building a set of 370s for my boat i have one done and ready to go
also building a set of 330s for vince so my second one is going to be a while
ill try and post some pics