Machining 3.0 SC Cylinders - Top Surface

[redjb944]

I have a set of stock 3.0 SC cylinders (Nikasil) that have damage at the top surface (that mates to the head). The damage is from loose head studs. I think .005 to .010" would have to be machined across the top surface to clean-up the damage and (I assume) the sealing ring groove would have to go down by the same amount. Is this possible?? if so, any recommendations on shops familiar with this process??

I read several posts on this forum that stated this is a bad idea since machining may (will) damage the area where the cutter comes into contact with the Nikasil at the intersection of the top surface and bore.

Also read somewhere else that surface grinding may be the way to go for the top surface and then (I assume) machine the sealing ring groove to correct depth.

any thoughts/info would be appreciated.

[Mark Henry]

Post a pic.

For light damage I'd use a glass plate and 220 grit sandpaper, take the worst one and count how many strokes it takes for clean up. Turn the cylinder as you go. Then do the rest the same number of stokes.
Any minor nicks left I wouldn't worry about and you don't need to cut the groove deeper.

Any damage more then that I'd let US chrome (etc.), replate and machine them.

[redjb944]

thanks for the feedback. attached pic shows the damage. my concern is that if enough material is removed to clean-up the top surface, then the groove for the sealing ring will be too shallow and allow too much crush of the ring. I'm thinking the groove has to go down the amount you take off the top surface. any thoughts??

[john walker's workshop]

The actual compression sealing takes place on the inner ring. Do the 220 grit thing and see if that area cleans. I use my drill press' metal table and sticky back DA disc.

[redjb944]

thanks for the input. will do the "220 grit" thing tomorrow. will post a pic of the results. as the man said..."what can possibly go wrong"