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View Full Version : OMC gurus... Has anyone seen this before???



Robbie B
12-07-2002, 03:37 AM
79, V6 Cross flow, new bores, new pistons (wiseco's), clearanced and finished to Racers specs, 5hrs into breakin (Racers recipe).
Thrust side of bores from just above port down to the bottom has mirror like finish, cross hatch nearly gone, is this normal??
The highly polished thumbnail above the centre transfer port (see photo ) has me concerned, I have never had this before.
The non thrust side of the cyls is much less noticeable but has a similar pattern.
The ring running surface above looks perfect.
Get this, the pistons look perfect ( see photo ) Small highly polished area around top edge of upper ring land is the only blemish I can see, if you can call that a blemish.
I have played around with flows since 86 and have not come accross anything like this before. This is only my second experience with wiseco's ( the first lot melted) always used OMC CCC pistons before.

Just had a thought........
Could it be piston rock in the bore due to the piston not being up to the correct operating temp??

Advise, comments, thoughts please. :confused:

Robbie B
12-07-2002, 03:41 AM
Piston.......

racer
12-07-2002, 03:57 AM
Somewhat normal on those pistons, but the width of the scallop on your piston is a little wide allowing the piston to rock.

Robbie B
12-07-2002, 05:05 PM
The cut away is 1/8' wider but not quite as high as the factoy CCC piston 1" radius cutaway. It is shaped to match the bottom cyl wall cut at BDC. Maybe I've over done it?????? Can't put it back so I will have to live with it!!!
Do I need to do anything about breaking the glaze at the bottom of the cyls or just put it back together, wish it well, complete breakin and give it hell?

Rob

racer
12-07-2002, 08:59 PM
Robbie,

One thing to remember is these rings have more tension than the old CCC rings so the walls will look different. Also the scallop is to let trapped fuel and air on the bottom side of the piston out when at tdc. Go run it.