Merc. 525SC
 

A friend of mine is considering purchasing a rebuild 525SC from a fellow OSO member.
The engine has been rebuilt with a roller cam and World heads...
The engine would be used in a 1997 29' Fountain to replace the sick 502MPI we pulled out a few weeks ago.
Gregg plans to reuse a set of Stainless Marine exhaust manifolds with Corsa "captain's call". Are there any problems running captain's call with a 525SC?
Another question is the idle speed (rpm) of a 525SC? Will it idle below 800rpm?
Is a 525SC good reliable power? The 502MPI certainly was for 480+hours...
What top end speed increase can be expected with this increase in power? The boat topped out at 67mph with the 502MPI.
Will the Bravo drive hold up for a while? or Will Gregg be replacing the drive soon after the engine.
The other choice being considered is a low hour 496HO.
Which would you fellows choose?

Re: Merc. 525SC
 

Pat,
I have a 525SC in my 1997 29' Fountain and love it. Seeing mid 70's mph with a stock 26 pitch 4 blade. Idles fine. The motor is all stock! I think that is why it runs so good! Good Luck with everything.
Dave :D

Re: Merc. 525SC
 

Hey Dave,
Thanks for the reply.
Do you have captain's call exhaust?
How loud is she at an idle? can you have a conversation without yelling?

Re: Merc. 525SC
 

The 525sc is a 454 mag with a little different cam and a Wieand 177 blower.
They used the Merc/Gil exhaust. The same that I now have on my 454 mags. The sound level at idle is very livable for me. However, my ehaust exits under a rather long integrated swim platform.

Re: Merc. 525SC
 

I have a 525SC with a crane 731 cam. I have it set to idle at 800rpms in neutral. It idles at 700 in gear.
As far as the exhaust, it should be fine, but that depends mostly on what cam is in the engine. A local guy here has a stock 525sc in his 29 Fountain and it has switchable exhaust.

Re: Merc. 525SC
 

The 525SC also differs form a 454mag in that it has 7.5:1 comp vs. the 8.75:1 of the mag engines.

Re: Merc. 525SC
 

Hmm, I didn't know about the comp dif. That makes sence with the small blower.

Re: Merc. 525SC
 

The 525SC also uses an adjustable valve train with Crane Gold roller rockers along with the Crane cam. Other than that, some blue paint, gil exhaust and a different timing curve, its pretty much a 454Mag.

Re: Merc. 525SC
 

Hey Guys,
Gregg put a deposit on the engine.
Should make for big fun next Summer.
Thanks for the replys.

Re: Merc. 525SC
 

Pat, did you ever finish the boat you were working on.