Twins to single conversion


I

Isabelle II

New member
Good day lovely people!

So after a long winter trying to get my twin 5.7 mercs repaired things went south and now having them both removed, Im thinking of doing a twin to single conversion on my Formula 27 PC so id like to find out as much information as possible, I know these boats come with a single package so im thinking it should not be too much work and a single within this boat obviously works. I guess im here asking if anyone has done this before on a 27 pc? if so id love to hear from you! Just trying to gauge the pros and some what cons of this although i only realy see pros to this conversion with the way prices for 99% of things have gone. Plus id have a spare engine and bravo 3 to either sell on or keep for parts :)

Looking for images of a single 5.7 within a Formula 27 pc if some of you folk would not mind sharing :D imainly want to see how a single sits and what the engine mounts mount on, Im thinking of making a frame myself from either aluminium for the mounts to sit on which id then bolt to the new structure beams i will need to place, while removing the main centre beam that divides the twin engines. IF anyone has any info/images on a single please share!

Thank you! :giggle:
 
Seems like a lot more work than just fixing 2 engines. I replaced both of my 350s myself in a garage in my 292 FasTech a few years ago now.

You'll need a much larger engine, mounts, transom changes, wiring changes, battery changes, etc. etc. etc. you'll lose maneuverability. You'll lose reliablity. (Get home on one engine).
I honestly see ZERO upside to this endeavor. You'll spend a ton of money, do a ton of work, and the boat will be worse than when you started. Have you priced parts for a 454 vs a 350?
Yeah I wish my boat had twin 6.2s or 454s or whatever, but 350 parts are 'reasonable' compared to the big stuff.

If you want to go all out, I'd see about putting two Mercury 300-400s outboards on the back - that's an interesting project.
 
I have a single 27pc and it would have been much better to have twins.

History
My 1994 came with single 330hp 454 carb motor. Had one heck of a time getting up on plane with 1/2 tank fuel and 2 people, and don't even think about more then 2 people

Change motor to 390hp 502 carb and did better but not by much

Added MPI to 502 so at 415hp and did better. Would get on plane with 2 people and full tank. If going out with 4 to 6 people, some have to go to cabin to get on plane

Had motor rebuilt by Young Performance and dyno shows 530hp and now it will come up on plane with 7 people and fuel. Does better with less people as would be expected. Had to change exhaust to thru hull and +3 risers so not to have reversion. The boats been great, but you have no room in front of motor. Has only about 2 inches so have to hang upside down to change raw water impeller.

I'm currently selling the boat and reason is I'm getting to old to hang upside down and all the other stuff. I'm buying a brand new Chap 280 OSX with twin 250hp Varado's. Going to Chap instead of Formula because I want twin OB's and would have to go to 310 to get them. I stll really like the boat, and it has cost me a small fortune just to get the boat to perform like it should. The next owner should be happy with it
 
Totally agree with @SabrToothSqrl and @AllDodge - lots of work, lots of money, and you will end up with a lot of frustration because you will hate the boat after converting it.
Not sure what the issue is with your 350's but I assume that worst case you need a couple of long blocks. There are plenty of guys out there that likely have rebuilt marine 350's that are reasonably priced with several hundred hour usage warranties. If you like your boat and want to keep it, this is the best way to go and its pretty easy to do. Get two engine stands, mount up an old motor on one and a new long block on the other and transfer parts from the bad long block to the good long block. Gives you a nice opportunity to check everything out and freshen up / replace anything that would become a problem.
This approach will also get you on the water this season. I had this happen 4 years ago when I went to fire up my motors for spring commissioning and one of the injectors stuck open causing that cylinder to hydrolock and destroy the piston. I launched just before the 4th of July - a little later than I wanted but still plenty of summer to enjoy.
 
Found my engines thread:

Winter Work

Starboard was impossible to start. Oil in water, and no compression on 3/8. I haven't compression tested port yet. Ignorance is bliss. I did do some work over the last few days. Starboard is almost ready to come out. Waiting on a friend with a truck and a crane. Port... I guess I'll do a...
formulaboatsforum.com
 
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