Is This Piston and Liner FUBAR?

[Tom Foley]

Send it my way , i'll pay the postage !

 

[Wally Teresch]

Don't know if this is the best thing to do or not but I have begun doing it to engines when I strip them down. I take a fine diamond bit in my Dremel and knock off all the sharp edges on all the ports on the sleeve. I hold it at ~45 deg and just take ever so slight a 'lick' off.

Got a pair of CMB 80 engines from Fleabay and upon examination I found the ports to have a near knife edge. I figured that was just asking for trouble and couldn't see any harm in knocking off that sharp edge.

Anyone else doing this?

Wally

instant timing change. i would never 45° the ports

Maybe I didn't word it correctly. I put the Dremel bit through the port and take off the sharp edge inside the port opening. I just touch the chrome plating to take off the sharp edge. The amount being removed might be 0.0025". Just to take the sharp edge from each port that has an opportunity to flake off or pick up the aluminum from the piston.

No I wouldn't grind 45 deg off the brass either.

Wally

 

[Scott Schneider]

Wally,

I did / do so figuring ALL the sharp edges around port windows act like squeegee edges peeling the oil film away. A ever so slight bevel / broken edge allows the piston to better float on the oil film present.

Doing this for years now have indeed seen less burnish type wear on pistons and service life is much enhanced.