ok guys im new here. sorry if this isn't in the right location on the page. im so far passed mad with this project.



so to start off here. this boat i purchased wasn't winterized correctly. the block froze. so im rebuilding a motor set up. some of these things i was talked into cause it sounded good. but google and everything else takes me all over the place.



here is what i have



original motor is a 1995 ( gen v) 454 magnum EFI/MP mercruiser multi port fuel injection. that's what top of intake says. it was all original from factory.



new set up is:

-gen v 454 block bored .30 over

-stroker crank. cast/steel nodular iron. 4.25 stroke 1 piece rear seal

-h beam forged steel 6.385 long rods. .250 longer then stock.

-piston forged .30 over .180 dome they yield 10:1 compression with 115 open chamber heads

-all lower end parts come internal balanced. (cam isn't included)

-xtreme marine 218/224 flat tappet cam with spring kit(roller cam wasn't in stock and won't be for wile)

-factory heads they are the rectangle intake port.

-factory intake( don't have pic at the moment)

- emi thunder alumium exhaust manifolds with stainless risers.

not sure if im missing anything else.



my issues that's im coming across with is.

1. since the internals are all balanced. i was told i need to zero out my flywheel or get one already done. or i could get a older 2 piece 350 flywheel since they are natural balanced flywheel. or next option is drop all my stuff with the new crank and all to get all balanced together.

2. since im changing the crank and all i will need to get the eco tuned.??? engine guy told me to put it together and start the motor and run it and check it out. said i might have to up the fuel pressure little bit and ill be fine.

3. if i need to tune this, how do i even go about doing it. I've looked online for days, and it just takes me in circles. with everything being named and called something else, and all these diff models and everything else. i chase around and get nothing. im at the point i just want this in the water already.





again sorry if its not in the right spot. im just at the point i don't know where else to go. and don't want to keep spending money

Simply tell your machine shop to zero balance your flywheel. They will mill or grind the counter weights off it to get it close to zero then spin it and touch it up until it is zero.
as far as your tune, your going to be over 9% bigger, 496 or whatever. At that point you essentially need a tune for a 502, between your cam, exhaust and extra cubic inches, I wouldnt consider leaving the stock tune. 9% more cubic inches, another few % for cam and exhaust, if you were just doing the exhaust, the 3 or 4% it leaned it out would be fine BUT lets say the factory tuned it RICH, they do, and at wot its at 11.8, if it leans out 14% between cam, exhaust, cubic inches, your wot afr would be in mid 13s, your hottest cylinder would be into the 14s and if you held it at wot, it would be game over after a while.
So since its a 95, im going to assume its still a mefi1 ecm and has long style 48 lb honda /keihan style injectors? I do Mefi tunes along with injector service, you can PM me for more info if you dont have someone local to tune it, I do this all the time. I will say, I will not do a tune unless its verified your injectors flow perfect and work right BUT I do offer injector/flowing/cleaning service, Smitty

Is this the real Smitty......................... doesn't he need a neutral balancer also

Try to balance it

Are you sure they came stock with 48 lb Keihin injectors? Small blocks had 26 lb and I thought the big blocks came with 36 or 42 lb injectors?

Stock tune would be fine for initial start, base timing set up and leak checks etc..but agree it would need some AFR monitoring for behavior under load.

Yes, he will need a neutral balancer too!

The 454/502 mag mefi 1 gen 5s used same injector as a 525, was a honda keihan style made for mercruiser, they flow 47 to 48 lbs on static test. The 500 efi uses a 36 lb, the gen 6 454/502s uses a 45/46 lb shorty made in italy. The L29 454 "base" motor used a 23 lb, as far as the sbc, not sure, Smitty

ok so you clearly no what your talking about. as far as the injectors they look like the honda injectors. i will get you photo of them shortly. from dealing with honda few years back they look the same. and as far as i know its mefi1 ecm. i only know so much. just bought this boat few weeks ago. my old boat had 350 with a carb on it. i was speaking to someone few hours ago online that lives in philly, and he gave me an email address to a guy that will flow test an get my injectors right and does some tuning. i also see a comment below this saying smitty that's what the guy i spoke with said his name was. so i will email that address with my injector pic an and serial number off the top of my motor and all and try to move forward. i will also post the pic of the injector on here in case your not the same person. at the end of the day i want this boat to run right without having problem. but also little more power. thanks for your reply.

as far as the flywheel im going to take it to the machine shop and have them blance it out. think i should drop the internal parts off as well? even tho the company states they are internals balanced?

also this page will not let me private message you at the moment. it says i don't have enough post. i just emailed the guy i got the email for hoping its the same person.

.30 over is a 468, not a 496. I don’t think you’ll be much extra fuel or much of a tune at that level to be honest. .60 over is 496.