Engine swap

skidrow

Getting engine rebuilt.. Motor is out and builder discovered a 6 inch crack on the starboard
side of block under the exhaust manifold.... Need a new block... Could jb world but
i say do it right... Had motor winterized by marina....he drains water according to merc and
goes extra step and fills it with antifreeze flush ...still cracked block...any feedback on winterization?

Black_Diamond

Don't even waste your time to JB weld or even weld repair IMO. Once the casting is compromised like that it will never be the same. 

Hard saying if winterizing was the cause really. Maybe your overhauler can help. 

skidrow

Have a completely rebuilt motor...383 stroker....new block...outdrive rebuilt...
corsa thru hull exhaust....now just waiting for the water...

duane.mosley

when you rebuilt the outdrive, did you have to change gear ratio to compensate for the added HP?

skidrow

No, the outdrive is a bravo 3 with a gear ratio of 2.20.

duane.mosley

sweet! have fun!

skuter99

If you have a 350mpi made into a 383 stroker does the ecm555 need new programming or will it learn itself??

212rowboat

skuter99 said:

If you have a 350mpi made into a 383 stroker does the ecm555 need new programming or will it learn itself??

there is nothing fancy about the ECM and engine on the older models.. the newer ones, which monitor exhaust and adjust fuel trim like a car would- are fancy in that the tables are 'live'.

the old computers operate off of tables... ala: "this RPM, this load as registered by MAP or MAF, then this much fuel"..... that's even how your car works while operating in 'open loop'- when it closes loop, much the same as the newer monitored marine engines, it brings all of the sensors into the equation and adjusts on the fly.  

so... if you're bumping displacement, there are three ways to go about it when trying to get the fuel trim right (and while using an older EFI system)- 

#1- you get the ECM re-flashed to accommodate the new displacement and dynamic ratio (compression and valve events based on camshaft profile) of the engine. 

#2- you work with someone reputable and install larger injectors... if the stock ones are 35# at 43.5psi (doesn't matter what the actual fuel pressure is, the industry standard or at least the emerging industry standard uses 43.5psi to rate the injectors delivery in either pounds or cc's/min) you may find yourself getting 37# injectors. 

#3- you get a different and calibrated fuel regulator- injectors are rated by flow at pressure- more pressure: more flow, less pressure: less flow... but you need to be aware that injectors spray characteristics change at different pressures... going lower than the design envelope means they may drip instead of spray- going higher means the stream becomes a 'pencil stream' instead of a misted spray... with the right injectors and the right pressure, though, the balance can be found without flashing the ECM or replacing injectors... the fuel trim tables present on the current ECM will become accurate again as the ratio to pressure equals what it needs... the ratio doesn't change, in other words, the number plugged into the ratio does.  

i ain't you, but if i were you and i ain't, the solid absolute response is YES you need to have you existing ECM flashed or purchase one tuned for your build... this avoids surprises and heartache. 

skuter99

Thanks for the great info!