I'd work harden those welds,ie,beat them almost flat w/ a hammer.then grind smooth

good call on the welds
cheers

I have 2 of the Mercury 525 EFI 502 CID engines I am trying to rebuild. I cannot find the serial number or model of engine in the specs label it is either gone or never been printed on it. I am trying to figure out which exact model and year the engine is to order parts for it. The Block has the numbers C272, C12561358. The cylinder head has the number 900 843425. The Intake: 12550669. The piston has the number 843302a1. Would appreciate any help.

Model: HP525 EFI
Displacement: 502 C.I.D.
Max WOT RPM: 4800-5200
Spark Plugs: NGK BPR6ES
Spark Timing: Non Adjustable
Fuel Octane: 87(R+M)/2 or 92 Ron International
Engine Oil: Mercury/MerCruiser 4-Cycle 25W40
Engine Coolant: Dex-Cool


Thanks