Offshoreonly.com - 525SC Rebuild Recomendations

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Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Q & A (https://www.offshoreonly.com/forums/general-q-20/)

- - 525SC Rebuild Recomendations (https://www.offshoreonly.com/forums/general-q/352679-525sc-rebuild-recomendations.html)

MILD THUNDER

03-19-2018 10:39 AM

I-043B 345cc, I-043C 310cc, I-043D 269cc

Mohavvalley

03-19-2018 11:47 AM

Funny thing is there is no letter after the 1-043, casting is just flat. Is this because it is a Merc application?

I'm also looking at a pair of pro topline aluminum 320 heads, but I've heard they had lots of issues. Would you go for the toplines over the Merlin's in a freshwater boat?

MILD THUNDER

03-19-2018 01:08 PM

I have never heard of a Merlin cylinder head being used by Mercury.

the 320 pro topline was the same head design as the EQ 320, and RHS 320. I believe when RHS was bought out by comp cams, they had no interest in the iron versions, so engine quest picked them up. Outside of marine and truck pulling classes, theres very little market for bbc iron heads in the automotive world.

F-2 Speedy

03-19-2018 01:47 PM

The 525 EFI heads by Edelbrock, I think were a 320 runner ?? then later on I think Dart made some 525 Merc. heads.....

MILD THUNDER

03-19-2018 03:03 PM

Quote:

Originally Posted by F-2 Speedy (Post 4616833)

The 525 EFI heads by Edelbrock, I think were a 320 runner ?? then later on I think Dart made some 525 Merc. heads.....

i think dart made some 525 replacement heads, but dont think they came from factory on 525s, otherwise theyd prob been 550s lol

adk61

03-20-2018 12:18 PM

engine build

Quote:

Originally Posted by phragle (Post 4614408)

Do a cam or aftermarket heads, doing both will put you up there...

For reference I am just finishing a build... 454 motor with a 731 cam and AK heads, .030 over and went to 8.5:1... 525sc blower should be a little over 600 hp,

I'm with Phragle... run AK heads :hitit:

Mohavvalley

03-20-2018 05:43 PM

Ok I'm looking at the aluminum heads, can I just turn down the boat by not over driving the blower to try and keep the the HP down if I do heads and a roller?

phragle

03-20-2018 06:23 PM

Quote:

Originally Posted by Mohavvalley (Post 4617075)

Ok I'm looking at the aluminum heads, can I just turn down the boat by not over driving the blower to try and keep the the HP down if I do heads and a roller?

Thats my plan.......

Griff

03-21-2018 01:44 AM

The stock 525SC pulley is a 3.25" upper and 6.5" lower if I recall correctly. I know it is 2:1 overdriven and stock boost is 5.5#.
Nobody ever made a larger upper pulley than stock that I'm aware of. Not sure what size you have?? I'm guessing 3.12" ??
The splined pulley is NLA so you would have to find a used one or have your blower shaft changed to keyed one.

phragle

03-21-2018 06:56 AM

Im keyed... :cool-smiley-011:

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