Topic: "Big Bore" oil ring job

[Hannibal Smith]

Well, machining a wider oil ring groove in the pistons to convert the "Henry Abe" piston kits to a 3 piece oil ring is a snap.

Didn't want to mess up the pistons, so I took my time in the lathe, and cleaned the chuck-jaws between each piston......and they all turned out perfect! Whew!

I machine stuff everyday for a living, and I still get nervous, maybe that is why I have a reputation as a good machinist

Anyway, I feel very confident with my new 3 piece rings. I purchased the made in Japan Riken ring sets, and they sure look quality to me. I am paranoid about counterfeit parts, and these have the Riken hologram and they came from BikeBandit, so I am sure these sets are legit.

[fastbroshi]

Nice job there Hannibal

[754]

 I hate chucking a piston on the skirt..or chucking the ring area..

 I try to make a plate to fit the chuck, with a hole thru the middle then pull piston up againt it using  the wristpin.


 Make a rodend like eye to fit loose over the pin, then a threaded rod & washer to pull it up tight against the fixture.. if you follow.

 Are you cutting one side only of the groove? Dial-test indicator is a must on this job..

[Hannibal Smith]

I hate chucking a piston on the skirt..or chucking the ring area..

 I try to make a plate to fit the chuck, with a hole thru the middle then pull piston up againt it using  the wristpin.


 Make a rodend like eye to fit loose over the pin, then a threaded rod & washer to pull it up tight against the fixture.. if you follow.

 Are you cutting one side only of the groove? Dial-test indicator is a must on this job..

That sounds like a good safe method- I used brass shimstock (.003) and then indicated each piston with a back stop ( fixed rod through the spindle trick) then machined to .109" width only taking from the skirt side, I used a cutter at an angle that ensures you get a perfectly parallel back "wall" on the groove.

The pistons were all perfect to .0005 on top to oil-ring groove distance, so the stop made it a 20 minute job.

[754]

 In Sept I widened the grooves on a par of big-bore pistons.. they were for 5.800 bore...

[Big Jay]

If you have aluminum jaws for the chuck, bore them for the piston size above the rings. Then take a face cut so them so it is dead square to the bore.

Put a top ring in the piston and put it in the chuck, up against the ring. It will now run dead nuts true when you turn it on.

[Jerry Rxman Griffin aka MuthaF'er]

OR, don't machine them and just do a search and you can find the Total Seal part number for 3 piece oil rings that fit our Henry Abe 900 pistons. I forgot where I put that info. May be in the TECH section.

[Hannibal Smith]

OR, don't machine them and just do a search and you can find the Total Seal part number for 3 piece oil rings that fit our Henry Abe 900 pistons. I forgot where I put that info. May be in the TECH section.

These are the "605" HA pistons, anyway, what fun is that?

[Jerry Rxman Griffin aka MuthaF'er]

Yeah, I know what you mean. Wish I had your talent and equipment!

My pistons are the same as your's.

Here's the link

http://forums.sohc4.net/index.php?topic=48656.0

[754]

 Jay, I got to ask if you are using a small lathe to do this? and if you ever have runout on the bottom of the ring groove.

 The reason I ask is; if there is runout, you can easily adjust it, if it is pulled up against the chuck with a drawbolt. ( a truing cut, plus a small inset 10-20-thou bigger than piston, will aid setup )

 The other problem I have with your method is the lathe I usually use (16in) has too much startup torque, For the amount I would feel comfortable with clamping the chuck on an aluminum piston, it would probably fly out, upon restart.

 Just a warning, I would not even sweat it on my smaller SouthBend, I can slack the belt tension and soft start it if necessary..