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470 retro to something else.....

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randyj

Regular Contributor
I've got an old boat that I simply like the design of. It's going to take some serious work but I'd like to get rid of the old 470 and put something else in there. Just wondering what problems I would encounter if I replaced it with something like a smaller 140 or bigger 350 chevy engine. Anyone have a clue what's involved in swapping to a different engine such as these? I've got both the old chevy II 140 mercruiser and an old 350 that I could build and put in the boat... some more serious renovation project... I'm just wondering if it could be done fairly simple.
 
Is it a merc 140 or a chevy @ motor makes a big difference you can't use the chevy 2 motor.

What size boat.

Be aware you will need everything from the motor back everything.
 
"I'm just wondering if it could be done fairly simple"

Simple answer, no. But if you have the time, patience, and most importantly money, you can do anything you want.
 
randyj, I am doing something similar to what you are talking about and pugetsounder hit the nail on the head! lol. My boat is 17.5 feet long and I repowered the boat from an old 85 horse outboard to a 3.7lx 180 hp I/O with an Alpha One r/mr. Of course, I had to change the entire transom configuration but I did finally get it to match up and just recently got an alignment tool and was able to allign motor. (alot of work) Do you really love the hull that much? Because I will tell you that it can become a love hate relationship! lol Anyways, be careful with what engine you decide to put into the boat because the ratio of the drive must match the motor. (if it is an alpha One I/O or prealpha) You could probably go with a 4.3 litre (v6) if the hull is big enough to carry it. Before I started on my boat I asked a guy that works for Almars Marine in Delaware and first thing he asked me is if the the engine would weigh over 800 pounds which of course it does not. Also, there are a few guys with 470's in 16 footers because of power to weight ratios. (but I think they are pushing it a bit). Getting to the point: You could probably put any engine you want in the boat to a certain degree but the problem is: (what do you have to change to make it work?)
1) Is the motor that you are going to pick compatible with the drive you have?
2) Is the drive the right ratio?
3) How many linkages and or controls will have to be replaced to do so? $$$$
4) Is the transom, stringers, floor in good condition?
If you decide to install a motor that is not compatible to the drive that you currently have then you will have to buy another drive. More $$$$$$ Just my opinion but if it had a 470 in it then why not rebuild it and just run that. Basically, nothing would change if you keep all your parts together. Or go with the 4.3 which has the same ratio as the 470 and I think all you would have to do is change the exaust system to a y setup. But!!! here is the hard part: I think you would have to mount engine mounts and brackets into the stringers somehow still allowing the motor and drive to allign properly. Whatever you decide to do I wish you only the best!
sincerely, Tom
 
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