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Converting volvo penta i/o to velvet drive

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mike rattigan

New member
I have a 1991 4.3 liter volvo penta motor from an i/o boat. I have changed the bell housing ,flywheel and starter and installed a velvet drive. Do i now need an external oil cooler. I have not seen an inboard without one . If so ,how do i hook it up and also how would i hook up the transmission cooler. I hope it is posible and i hope i do not have to do ther modifications . Thanks in advance mike
 
Mike,

Yes, you need a heat exchanger/cooler on your velvet drive. I'll see if I can find an illustration, it's pretty strait forward.
 
mike rattigan said:
Yes i know i need a transmission cooler. I do not know if i need an external oil cooler . it seems all inboards have them , mike
Click to expand...

Sounds like you're clear on the transmission H/E (H/E =small heat exchanger) but you're wondering if the engine oil needs to be cooled, correct?
4.3L in what size hull?
Twins?

As long as you can find a means of disrupting the sea water path to the engine (RWC or Closed Cooling system), you can install another H/E for engine oil.
This H/E must be suitable for engine oil volume yet offer ports large enough to not restrict sea water flow.

(example only)
images


You may want to look into one of the Hayden remote oil filter thermostat control valves that work hand in hand with an oil cooler .
If memory serves me, there is a Hayden unit that is adjustable for temperature as to not over-cool engine oil.
images


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Ricardo thank you so much . Thanks to you i will sleep tonight. I have a 1947 single screw 22' chris craft sportsman.i wanted to put modern power in the boat. So i bought a clean 4.3 volvo penta i/o motor. I was told all i would have to do is change flywheel.bell housing and starter. Now i am discovering there are other items involved. Just so i can adapt and use the motor i am thrilled. I am sure i will have many more questions inthe near future . Thanks again ,mike
 
Ahh new information, here is what i have found. in general small block motors do not need or use external oil coolers.so for what i am doing, that is taking a volvo penta 431 i/o motor and converting to velvet drive inboard, here is what i need to do. install inboard type flywheel, bellhousing ,starter andi beleive 1 other type of plate on the flywheel to accept the velvet drive. the transmission cooler on the velvet drive is then attached to the raw water pick up . the raw water passes thru the trans cooler then in to the raw water pump. thanks all
 
Mike, I have to ask: Why are you wanting to chang from a Volvo Penta I/O to an I/B on a 22 foot boat?
Am I missing something here?
I do read where you say "More Modern".... but Mike, today's I/O users are very familiar with the AQ series V/P as still being one of the best I/O's that you could want to own. Add the Duo Prop addition to this, and it doesn't get much better.

Just curious as to why you'd want to do this on a 22 footer!


Back to the 4.3L and your Velvet drive.

Any engine that is Borg Warner Flywheel Cover (bell housing in the automotive world) capable and offers a Marine Exhaust adaptation, can be made to work with any I/B transmission that is also Borg Warner pattern.
So there should be zero issues mating this engine to the 6 bolt B/W mounting pattern Velvet Drive.
This is a marriage made in Heaven.
Even the Volvo Penta I/O B/W drivecoupler will work.

You may need the the 168 tooth flywheel in order to work with a F/C mounted Starter Motor.
Otherwise, if the OEM postion starter motor would work for you, you can leave this As Is and use the 153 tooth flywheel.


Here's a SBC Borg Warner pattern Flywheel Cover.
The starter motor position may vary, but the 6 bolt B/W pattern is pretty much standard B/W.
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Not sure which Velvet Drive you would be using, but again, here's the industry standard 6 bolt B/W pattern.
(there may be a Velvet Drive that requires an adapter.... but I'm not sure)


Liberty_5000_1_site.jpg
 
Rick,

I think you missed the part when Mike mentioned the boat is a 1947 Chris Craft 22 foot Sportsman, he would be going from a flathead straight six, to the 4.3.
 
Bob, you are exactly correct.... I missed the 1947 part!

Mike, I couldn't figure out why anyone would want to make this type of change....... now it makes sense to me.
I'll have to apologize for my missing that!

This is so you guys don't have to beat me up.... I'll do it myself! :D

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Mike, I'm thinking that the Borg Warner information should still apply.

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yes i am repowering a 1947 chris craft inboard. however the motor i am using was taken from an i/o boat. thanks for all the help guys. this is a great site. mike
 
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