Hey guys,

I hope your well.

im in the process of rebuilding my 700sci as the headers leaked and the liners rusted (Salt water)

my question is, what do you typically bore to and which pistons do you install. I cannot find oversized Mercury pistons for the 700sci so I assume I will have to go for a je set etc..

Thank you for the help

The o.e. Pistons are je. Your machine shop will have to bore the block until it cleans up, and then tell you what size you need to get.

o.e on the 700's are Mahle pistons - very hard to find outside of mercury and to get any info on.

When i look online it seems to be easiest to find pistons in the 4.5 bore range so I assume boring to a 509 is most feasible. I hear some people saying thats a bit much and some saying its fine so I wanted to know what the general consensus was on this.

Thank you all

Ayuh,..... .030" is pretty much a standard overbore for just about any motor,.....

I wouldn't have any issues at all running a JE over a Mahle piston.

Bore the block to clean it up. Your machinist can contact JE to get the right pistons. Balance and be done.

Doing quick search Diamond Racing Pistons lists ‘direct replacement pistons’ in many overbore sizes for the 600sci/700sci.

https://diamondracing.net/c-661-pist...ry-racing.html