4.3 to 5.7 swap questions

[Gsxrspankya1]

Hello all. I recently inherited a 97 1900 sr from my in laws. It currently has a mercruiser 4.3 that has
ALOT of water in the oil and sat all winter, I'm very mechanically inclined with moderate boat experience
so I know that this motor is finished. Every boat mechanic I know tells me it's not worth it to buy another
engine but this boat has currently received new flooring, carpeting,upholstery, guages, and a lower end so I beg to differ. My questions are A. What are you thoughts, input, suggestions? B.how hard is it to drop a 5.7 where that 4.3 was? And C. Should I try to rebuild the existing 4.3? Or am I just asking for trouble doing so. Any input wOuld be greatly appreciated at this point as I love this boat and have done most of the work on it for the past five years before the water ruined the engine.

[seapuppy]

Gsxrspankya1 welcome to the zoo.....there are several schools of thought about this ....I've test driven the same boat with a 5.0ltr with an A1G2 drive and man was that crazy wicked fast......quick and insanely fun to drive...so....the 4.3ltr engine is ok for a boat that size...the other option for that sized boat is the 5.0ltr....so..putting something larger would require either massive detuning due to the drive unit..it's not designed to handle the hp of the 5.7ltr engine...so...your more or less stuck with 4.3/5.0ltr engine...replacing the drive to the b3 drive would definitely be cost prohibitive....so..the a1 drive is the simplest option..

now for repairing or replacing the engine....I really can't logically answer the rebuild option of the 4.3ltr engine until it's torn down...if the heads are cracked...if that's it..then replace the heads and associated gaskets......change the oil out a few times...and you would be good to go....
so...the 2 options you have are to tear down the present engine and determine the extent of the damage..make repairs or buy a short block if the heads are ok...stick the old heads on ..a give it a go....if the heads are gone...buy new heads....

now if your looking at insane performance ..then you can get a crate marine engine for a few grand that is basically a drop in option...the v6 is pulled out and the v8 dropped in......that's pretty much it...
whatever you decide.....keep us informed and take a ton of photo's ...we like lotsa photo's.....

SP

[Gsxrspankya1]

Seapuppy, thanks so much for the quick response, in my search for a good site to help me with this
project I came across this one and it was actually your posts that led me to believe this was the best
which is great because it will be myself that does whatever it is gets done to this boat so I will have
A lot of questions for sure. Never thought about a 5.0 that's a great idea. Do you know of any reputable
but affordable manf. or distributors for such an item? Jasper? Or just spend the money for merc? Again
Thanks so much.

[seapuppy]

well...sucking up to me ain't gonna help ya any!!....just kidding....
there are several reman companies about....the best report I've heard of is michigan motorz...there are others and I'll list them here in a second..but if it were me...and it's just because I like to keep things stock...I'd go with a merc motor..they make reman's at a decent price....they are pretty reliable and come witha warranty....so..naturally it's your money...but for a 5.0 ltr engine...I think they are complete....you basically want one that is already dyno'd and ready to go..no adjusting timing and no messing with the carb...just plug and play....
you also need to really make sure they are marine grade engines....do not under any circumstances put in an auto engine......they are not designed for the marine environment.....

Company
S&J $1836
Powertrain Productt Tech $2,176
Advance Marine Engine $2,095
Remanufactured. Com $1,890
Gearheads Engine $1,929
Hiperformance.com $1,816
Rapido $1,450
Michigan Mortorz $2,049


SP