bcfountain

here is my 2cents on your delima.I have a 27fever also....its even a signature series like yours.its a 94.502mpi.it has the vst injection system.when I bought the boat it had 383hrs and it ran great for 2yrs.i started having fuel related problems with the vst.I know very little about fuel injection.but I do know how to tune a carb.long story short.when the motor did take a chit @437hrs .I rebuilt it and had the injectors flowed and cleaned.i also had the entire fuel system serviced.after all that I still had problems with the vst vapor locking.i know this has been a sorce of problems for a lot of boaters.rather than pay someone to work on it I did what know.i removed the injection,and installed a carb.did I lose any performance,no.did I take a hit on gas consumption,yep.a 1/2 gal less.dont get me wrong.i would have rather kept the injection,but wasn't ready to pay a marine shop to do the work,or learn how to work on injection.after all,i had plenty of manafolds and carbs left over from my drag racing days.so,this was a easy choise for me.i agree with others on here.aleast pull the heads off or leak down the motor.think about.you have a performance boat.people buy a permormance for one reason,,,,,thats to run fast,run hard.i can say this.when I did tear down the motor @437hrs.it need it.also.if you have injection.you are liminted to what you can do as far as engine mods go.i know a lot of people on here will disagree with that statement.but it came from mercury.hope this helps.

Diamond Dave

^ Curious why your engine blew?

bcfountain

high pressure pump got weak and leaned the motor out.put two holes in the pistons.

maineriverrunner

Think I'm gonna do a compression and leakdown test after this season. My suspicion is it should be freshened atleast. Interested in any experience with some mild mods on these motors such as a cam swap. I want to keep it EFI for sure though.

oneanddone

725hrs. On my 454's /blowers did head/valve work at 600 , cams were worn replaced with roller. Just freshend the blowers going for 1000. Oil pressure is great and don't use any oil ....

Diamond Dave

Did you add the blowers to your stock engine after the fact or were they built that way?

Crude Intentions

iTrader: (1)

Diamond Dave. Bills engines were stock 454/425s that had the 250s added on top.

Diamond Dave

Do you happen to know if they had a good amount of hours on them already when he added them?

Crude Intentions

iTrader: (1)

Not sure. He is the third owner of the boat. He has talked to last owner and got a good bit of history. I'll tell him to check it again. A bbc bottom end is extremely strong and most failures are catostrophic not wear. Either from improper tuning or water ingestion or improper maintenance.

Movie muscle

All comes down to maintenance. I've seen 2000hrs and the motor be fine! I've seen dead at 100hrs, or less. Stock merc 502's and 454's can last a very long time. Don't overheat, keep fresh oil, don't over rev, nothing to lean them out or cause timing issues. Along with no water ingestion issues from bad manifolds or risers. However the above factors seem to come into play far to often. Do a compression and a leak down, along with a bore a scope camera. If all's good run them. Stay on top of maintenance and they will serve you for many hrs to come.