Rebuild or repower
 

I currently have a gen 6 454 mag mpi freshwater Cooled straight inboard with a zf transmission in my 27 conch center console. I'm contemplating having the block rebuilt for around 4500 over the winter and putting all new coolers etc back on. A few people are stating to stay away from rebuilding and just get a new engine. The only engine I have come across in gas with that torque and hp is the ilmor 6.2 gdi. Marine Power has a model but I'm being told parts are tough to come by. The ilmore engine will be around 32k . Just wondering if anyone has had any luck with rebuilds.
thanks

I would rebuild what you hand if you have a good shop. At least you know what you are getting.

Find out what is included for 4500. Sounds cheap?

Where are you located? Maybe a member can recommend a good rebuilder for you?

I'm in southeast mass. I was referred to custom automotive in weymouth ma. Have heatd a lot of good things about them

What is wrong with your present engine that you think it needs rebuilding ? How many hours ? I would be a little leery of anyone who says they can do one of those correctly for $4500. I can look up some parts prices to be sure but i would expect closer to $7000 Does Mercruiser offer a reman for your engine ?

Currently 2700 hours. I do manifolds and risers every 4-5 years and keep up on all the maintenance. I commercial fish with this boat so I'd rather do it over the winter than deal with it during the season. It's running great but I know the day is coming with the hours. No I can't get a gen vi 454 block otherwise I would

I would say you got your moneys worth out of it :) I have a nice 2000 Gen6 454 at the shop that would be a nice foundation but I am in Maryland. You might want to try and find one up closer to you and have it built and ready to swap over.

Is the block you have freshwater Cooled? I have looked all over up my way haven't been able to find anything

Gen VI blocks can be elusive, but they are around.
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Aftermarket blocks are a good value once you add in the machining costs and used block cost etc.

Fresh water cooled...I would rebuild. You've proven the combo and setup. Changing anything can create unforseen issues during your working season. 2700 hrs on a mild roller cam...it may still be gtg.

​​Have you done a compression test?

If you did one every season when you do plugs, you have a baseline of how it's doing. Maybe just needs a hone and re-ring and clean up the guides and valve job.
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Merc has a very good handle on engine tolerance specs in the shop manuals.

A Gen VI 1999 Merc I just tore down, with 600 hrs had 4.251" bores and cross hatch.
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Commercial fish….SE MASS…new manifolds/risers every 4-5…..sounds like salt water to me…