Hello

Finally in the last stages of planning of re power of my 35 commander salon (1972). 

Plan is now two small block 350 carb engines.

Will also change transmissions and the fuel tanks while the engines are out.

What transmissions do I buy for the 350 chevy marine engines?

Will my stock shafts be fine or do I need new shafts?   My boat came with the Ford 427ci engines so im not sure if that makes a difference in shaft size.

Plan is to take the tanks out once the engines come out then have someone make me some new ones or if I could buy new ones before hand so I can just take the old ones out and swap in the new ones that would be best.  

Any advice is greatly appreciated

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I think your engine choice is going to complicate your re-power. Your existing props and transmission reduction ratio was optimized for the 427 torque curve and the small block 350 will definitely will not be even close.

This is not to say that you cannot or should not choose the 350 small block engine however if you go this route you will either need to also install new props of a lesser pitch and or dia. or else select a higher numerical transmission reduction ratio.

You have not stated what your future boat use habits will be so I would caution you on what power train selection you make. You will need to define what performance envelope you desire at completion of your re-power.

Personally without getting into all of the details, I think if you would consider using big block Chevys, your re-power will be cheaper and simpler as the hp and torque curves will be very similar allowing you to keep your existing props and the boat will perform similar to its original design. You would also continue to use a transmission reduction ratio of app. 2.5:1.

If you go the route of the small block Chevy, to get the same hp output the engine rpm will need to increase proportionately to the difference in the displacement. This is just a ball park estimate but you will need to turn the small block engine at approx. 5000 rpm at full throttle. If you use the same props, your reduction ratio would be around 3.125:1. Also note that your cruise rpm will also be proportionately higher. This will also likely mean that to get the high end hp, your camshaft selection will likely result in decreased low end torque which your greater numerical reduction ratio might or might not compensate for.

If you are just after a cocktail cruiser, then you can make some performance compromises to accommodate the new torque/hp curve.

No matter what direction you choose, you will need to view the engine, transmission, prop, and prop shafts as a complete system with project end performance goals in mind. This means talking to a prop shop and your engine supplier, getting a complete integrated package from a marine power company, or else select an engine as close to identical as your existing engines.

My own personal biases are towards big cube, high torque engines that will give good low rpm performance and engine longevity, basically a big block engine.

My last boat was a CC 33 Sports Sedan. The boat had 350Q motors with Paragon p32 transmissions with a 1.5 to one ratio. Prop shafts were 1 and 1/4 inch in diameter. Propellers were 15x17. Cruise was 16 knots at 3200 rpm and 23 knots at wide open throttle. Fuel burn at cruise was 12 gal per hour for each motor. Your boat is16086 lbs. and my old boat was 12500lbs. I don't think small blocks area good choice for you for two reasons, 1. Loss of performance will reduce possible resale value, and 2. Your out of pocket cost for motors, transmissions, and props will exceed the cost of repowering with 454 (7.4) or 502 (8.1) motors. If you are set on small blocks the 383 is a good choice, they have almost as much torque as a big block, while being a lighter, and smaller package than big blocks. Lastly CC didn't offer small block power for your boat, that says CC didn't feel their. performance would be acceptable.

What are your reasons for choosing a 350?  If you found a deal on them and are stuck with them, is the only reason I can think you would be sticking with them.  An engine shop can upgrade 350s to 383 engines, much better torque, which makes them much more appropriate for marine use.  The 8.1 would be another really great marine engine, also has great torque for marine use.

350s will work out just fine if you go that route. expect a cruise of about 17mph . The stringers in our 35s  were all built to accept small Block chevys . If you look under the wood spacer blolcks under your rear engine mounts you will find where the factory just filled them in to accommodate the big block 427 option. 

In this photo you can see the blocking that was added by the factory for the 427 fords. 

If your going thru the trouble of getting new transmissions , You can go with a a traditional set of Velvet drive 72C tranys  but only if you pick counter rotating engines . With The 72C's  you will also be mounting your engines in line (at the same angle as your shaft logs and struts) Transmissions - Velvet Drive Transmissions 

You can also choose to go with a ZF 45C transmissions which also mount inline like the Velvet drives do

 ZF 45 C Marine Transmission | ZF Hurth 45 C Marine Transmissions (t...

Or , only if you choose to buy standard rotation engines (both engines are left hand rotation) you can use ZF 83A  tranys. ZF Hurth ZF-63A Marine Transmission (michiganmotorz.com) however they are being pased out for the 68 .

All three options will require some mods to your stringers however being that the ZF A Tranys are of the down angle variant this will require a bit  more modification to make the top surface of your stringers  flat at most of the angle is accomplished in the transmission itself  . The good news is that you will gain over a foot of space between your bulkhead and the front of your motors as the ZF gears are much smaller than your current paragons. 

I went with the 8.1s  with the ZF A gears in my 35.  

I also replaced my gas tanks with new aluminum ones that are rectangular instead of round and gained capacity .  However being that you have a salon model , your tanks might be different than mine. 


Thanks for the replies guys.

You have convinced me to go Big blocks.    Works out as I have two 489ci short blocks here and just ordered two sets of heads for them.

Questions if anyone knows...

Did the original 427 fe engines both rotate in the same direction? 

I guess what im getting at is do I build these new big blocks to rotate in the same direction or coutner rotating.   I was plannning on buying two new ZF65A transmission to go with them and not sure if the trans are supposed to counter rotate or the blocks

If you want to use ZFA tranys . you will need to have both engines running standard rotation. 

The orig FE motors ran counter rotating engines and tranys. 

you will still have counter rotating props but on the ZfA tranys one  will run  "backwards"  to give you counter rotation props. 

10-4 sir both engines standard rotation and then use one std rotation ZFA trans and one revers rotation ZFA trans.   Than you sir.

Jeremy Goldstein said:

If you want to use ZFA tranys . you will need to have both engines running standard rotation. 

The orig FE motors ran counter rotating engines and tranys. 

you will still have counter rotating props but on the ZfA tranys one  will run  "backwards"  to give you counter rotation props. 

No,

The tranys will both be the exact same . You'll  just hook up the shift cable  "backwards" to give you a counter rotating engine 

https://simplicity-marine.com/ZF/ZF63A/Description.htm



Heimlich2010 said:

10-4 sir both engines standard rotation and then use one std rotation ZFA trans and one revers rotation ZFA trans.   Than you sir.

Jeremy Goldstein said:

If you want to use ZFA tranys . you will need to have both engines running standard rotation. 

The orig FE motors ran counter rotating engines and tranys. 

you will still have counter rotating props but on the ZfA tranys one  will run  "backwards"  to give you counter rotation props. 

Jeremy im sorta confused... so when I setup the engines and order the camshafts do I setup two standard rotation engines or one standard and one reverse rotation engine?

In older boats they ran engines in opposite directions.  In modern boats they run both engines the same direction, but run one transmission in "reverse" to get counter-rotating props.  Old (original) transmissions could not run in reverse continuously.  So if you are putting in modern transmissions, better to build two identical engines.

If you're going with the ZF Tranys than you need two identical tranys and two identical standard rotation engines . 

Heimlich2010 said:

Jeremy im sorta confused... so when I setup the engines and order the camshafts do I setup two standard rotation engines or one standard and one reverse rotation engine?
Ok so standard rotation port and starboard engines as well as standard rotation port and starboard transmissions. Got it.

So both props turn the same direction?

What was the reason for the original counter rotations and are the downsides to standard standard setup we are talking about about

Sorry if I'm missing it here

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