1993 245 w/ cylinder bore issues

[mrcrsr]

i have some questions concerning the nikasil bore on a 2.5/ 245(i know i should search previous posts!) anyway, i haven't checked out of round/taper yet, but assuming they are good, what are my options?? 3 cylinders have lite scratches,(longitudal), i can feel them w/ my nails, what are my options, or how do i proceed??

[Jay Smith]

You can't ASSUME they ( the bores ) are round , a dial bore gauge will tell wheather your bores are egged or straight. Mercury gives a .006" tolerance which is riducilous as that large out of round condition will allow a new set of rings to leak by like they're not even installed... I strive for 1/4 of a thousand ths and if they are more than that I straighten them .

As far as your scratches , on a nicom bore Id rather have an up and down scratch than a chunk of coating missing. After the bore is round I use a ball hone made exclusively for Nicom/ Nic. that I get from Goodson( www.goodson.com (http://www.goodson.com) ) then finish up with a plateau honing brush brush, makes a Nicom/Nic bore look like a mirror...If you don't have access to these you might try cutting a Marron grade scotch brite pad the diameter of the bore and instert in then put a normal straight hone ID the scotch brite and slowly scuff the bores...( I've never done it that way but I hear of folks that don't have access to the hones and bruches using this and other methods..)

Good luck,

[mrcrsr]

thanks jay, i have a dial bore guge and a sled w/ an indicator to do my out of round/ taper measurements, i saw the .006 spec in the merc manual and thought that was a little silly!!! how thick is the nikasil coating???

[Jay Smith]

Coating differes per hole and application needed but I'd say at least .010" or so ( just guessing )

good luck,

[ChrisXS2003]

How do you measure 0.00025 inches? Is that what you meant or is that a typo?

Chris

[mrcrsr]

it is .0025 he is saying, i come in around .002-.003 out of round, taper, so i am good there, i used my ball hone, most of the scratches are gone, there is nothing i can feel w/ my nail, it didn't take much honing at all, i cleaned thwe bores and used a qtip w/ muriatic acid on any spots on the bores that i wasn't sure about the nikasil, and i had no fizzing, so i guess i am good to go, i just want to go over the bores w/ the scrotch brite and give it a bath!!! thanks jay

[Jay Smith]

Lets just say that I CAN alter the bore's shape and CAN get it SOOO close being "round" that the dial bore gauge won't move but the thickness of the line on the dial gauge and I'd say thats about 1/4 of the increment of a thousand Chris that the dial bore measures in thousands , SOOO what would YOU call it ? I call it 1/4 of the distant from one thousand mark to the next larger or smaller measurement ....

Lets say its just a "scoach" .....Hows that????