Question about Blue motors

[Carl C]

Are all Mercury racing motors made completely by Mercury or are some based on BBC blocks? Mainly, does Merc. cast it's own blocks; including the 525 EFI? I know that some components come from aftermarket suppliers but what components are made in house by Merc.?:alligator

[big bore]

a 525 is a 502 long block from gm with mercs hp cam and valve springs

[RickSE]

HP500EFI & HP525EFI
CNC 502 GM HP block.
CNC GM Iron Cylinder Heads for 500.
Custom Aluminum Edelbrock Cylinder Heads for 525.
Merc. Racing forged connecting rods.
Forged pistons designed by Merc.
Crane roller cam, springs & rockers.

HP600SCi
Pretty much the same as the 525 but with a 3.3L Lysholm SC.

HP700SCi
Pretty much the same as the 600 but with a different cam, hardened crank and full floating wrist pins.

HP850SCi & HP1075SCi
Are in a world of their own.
557ci tall deck blocks.
Not much info on the rest of the parts.

All these motors are hand built by Merc. and do not come assembled from GM. I've heard that Merc. uses varoius vendors for their parts, GM, Lunati, Crane, Edelbrock.

[Pismo]

The big ones are still 502 blocks bored to 4.5 and stroked to 4.375 to yield 557ci.

[KRAVEN]

The small ones are stroked 350's adding up to 377 cu.in.
KRAVEN

[Carl C]

Very helpful info. Thanks.