2bbl vs 4bbl Merc 470s

[25thmustang]

Alright, the twin Mercruisers in my boat are "dead" from what the previous owner states. Says one locked up soild, and one struggled to drive home before going itself. He then said the mechanic labelled them seized and he sold the boat. I found a guy a couple hours away selling a pair of rebuilt motors. They are older, but 330 hours on the boat and zero on the rebuilds. Here lies the issue...

My boat being a 27' came with the 3.7LXs which were 4bbl motors. His boat was a 25' and came with the 3.7Ls which were 2bbl. My motors have recently rebuilt cars and good intakes. Would it be as simple as an intake and carb swap onto the 3.7L long block. From my research the 2bbl vs 4bbl is the only difference between the motors.

If anyone knwos about these motors, I would love to hear if I am correct?

 

[bhammer]

Re: 2bbl vs 4bbl Merc 470s

Many people will tell you to trash the idea of going back with 470 engine. I had a single 470 and had good luck most of the time. Lots of power for a little gas. If you can, I'd replace with another engine. Just becasue of parts and maintenance. Eventually, you will have to do the speedie sleeve fix on the cam shaft. When I was looing at a re-engine, I could go with a small V6 and get it done cheaper.

Now, on to your question, from what I understand, yes, just swap the carbs and you are all set to burn more gas for a little more horses depending on the carbs coming off. I heard that the setup for the rochester 2 and mercarb 2 are different setups and had different fuel pumps or feed line or something along those lines....

The best palce to double check this is over at http://www.breezeworks.net/cgi-bin/...ics.asp?ForumID=1&PagePosition=1&ThreadPage=1 There, it is all about 470 engines.

If you can, take off all the goodies such as exchangers, water cooled voltage regulator and alternator stator / rotor assemblies. You can kepe them or sell them on Ebay for some decent cash.

 

[25thmustang]

Re: 2bbl vs 4bbl Merc 470s

I would love to repower, but it would cost 3 to 4 times the money. Not only that, but the motors in this boat are so close together I wouldn't be able to toss anything other than 4 cylinders or inline 6 cylinders in it. I wouldn't want to spend $10,000 on a pair of 3.0s or something...

As long as the carbs, or carb/intakes can be switched and the boat will make the 180-190 hp it was rated for I will be happy.

I know all about the camshaft seal issue, which will most likely be addressed before the motors get dropped in the boat.

I will check that link out, and thanks for your reply.

 

[bhammer]

Re: 2bbl vs 4bbl Merc 470s

Well, the engines being close would be an issue. Good luck getting it all done. If it were me, I don't think I would do the speedie sleeve on a fresh engine. You'd probably get good hours from it before it started to leak if it even did. Good luck.

 

[25thmustang]

Re: 2bbl vs 4bbl Merc 470s

Well from the owners response the top end was rebuilt, not the bottom. He claims 330 hours which are really low but if I have the motors out we have two engine stands, and are mechanically inclined (we race cars, have 4 or 5 of them we drag race). I think it's kind of piece of mind for me, knowing they will be in there and good for years to come.

Thanks for the replys and the link, that site looks great for the 470 info there.

 

[JoChek219]

Re: 2bbl vs 4bbl Merc 470s

intake and 4bbl ...good to go but not sure about the fuel lines as stated earlier

 

[25thmustang]

Re: 2bbl vs 4bbl Merc 470s

Yeah, I will have to see, the motors in my boat are complete, so I assume my fuel lines would work on the new motors. I guess I really just need the long blocks minus the intake.

Going tomorrow afternoon to look at the motors and hear them run.

Thanks guys.