1972 Mercury 80hp 800 serial 3192882 rebuild

Due to low compression I would like go ahead and rebuild this motor serial number 3192882.My question is there a difference between low dome pistons and high dome pistons.Or does this only go for the inline 6's not the inline 4's. I was reading somewhere more torque with low dome pistons versa high dome.Thanks
I also would like to hone out the cylinders can someone point out what they would recommend concering a flex hone (what size and grit)

Re: 1972 Mercury 800 serial 3192882 rebuild

Only the type pistons that came with that motor can be used. Some of the earlier big fours used the old crossflowr pistons; later ones used the power dome design. They are not interchangable.

Jeff

Re: 1972 Mercury 800 serial 3192882 rebuild

Hey Steve that's some bug or is is this still the same motor? If the cyls aren't scored,a honing,new rings and while in there I suggest you do the bearings and top and bottom end bearings as well.Enjoy

Re: 1972 Mercury 800 serial 3192882 rebuild

Yeppers its still the same motor.I have got problems keeping it running in gear @ Idle,bleed restrictors are gone and compression is down to 115 on the number 1 cylinder,the rest are @ 125 and it has a terrible rattle.So I figured I might as well go ahead and tear her down hone out each cylinder replace rings maybe number 1 piston,also thinking on braizing the restrictor holes shut and drilling them out to spec's.Possible new reeds and bearings. Another thought considering $$$$ is to junk this all together and invest in another motor.Thanks for the response guy's.