Isn't it amazing how the same problem so often brings people to the same odd
conclusions. I didn't use Bon Ami (I didn't know what it was) I used
Jeweler's Rouge. Other than that, and your care in cleaning up afterwards,
it's almost the same deal. I avoided the cleaning issue (but maybe screwed
up the roundness) by using a dummy piston to lap. The first one I made out
of Lucite and it screwed together to hold the ring. Then my boss told me if
I ever ran Lucite on the lathe again he would through bolt me to the milling
table, so I cut apart an old piston so I could take the rings out without
springing them--I drilled holes through the crown into the piston pin boss
and tapped the boss. Then cut the piston apart through the top ring groove.
I could stick a ring in. tighten down the two screws, and off you go. Of
course I still had to spring the ring to get it on to the real piston, and
that might be where I lost some roundness and where Kas' approach is
superior.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of kas kastner
Sent: Tuesday, February 10, 2004 8:21 AM
To: fot@autox.team.net
Subject: Re: 86 MM Chromium Rings-Help
If I had just remembered this stuff before I'd have had another ten
pages for my book. I used chrome rings in my TR-4 engines and found that
lapping them in first saved a lot of breaking time on the dyno and always
gave a higher power number and a lot less blowby and early loss of pressure.
My system is not fun to do but here is how I did it successfully for lots of
years & engines:
With the pistons you are going to use fit all the rings making sure to
already have the end gap checked. Fit the correct rod.
Then lay out four pans that will hold about a quart of your favorite
cleaning fluid. ( I used lacquer thinner cause it was there and no one was
lighting fires in the shop)
Mount the sleeve in a fixture to hold it .
(such as easy gripping in the vise)
Make up a thin paste of kerosene and Bon-Ami ( yup, the old time
cleaning powder) The paste should be about the consistency of cold 50 weight
motor oil.
Apply a lite coating to the rings of the piston that matches the sleeve
in the vise, and a lite smear to the bore of the sleeve
Fit your ring compressor to the rings just as normal.
Fit the piston into the sleeve and give it ten strokes , one up and two
down and so on.
Remove the assembly from the sleeve, carefully remove the compressor and
ABOVE ALL, DO NOT TAKE ANY OF THE RINGS OFF THE PISTON. DO NOT DISTURB
THE RINGS.
In the first pan of cleaner use a small paint brush to start cleaning
the paste off the piston and the rings. After the worst is removed go to the
second pan, DO NOT TRY TO MOVE THE RINGS. Work with a brush again to clear
the paste residue.
Now go to the third pan and very carefully by gripping the ring away
from the ends move it slightly and a little more and a little with the head
of the piston submerged in the liquid more until the ring is free to turn
easily. Do one ring at a time, this is not the time to be lazy.
On the last pan of fresh cleaner. Move the rings as above several
rotations on the pistons making sure there is no gritty feeling.
Now that the pain part is over, wash in hot soapy water and blow dry and
immediately coat with WD-40 or similar type oil. Do not try to remove or
bend the rings or pull on the ends.
You will see a fine grey line on the top edge of the rings showing that
they indeed are lapped into the bore. Not only that the rings are ROUND.
(keeping them round after the lapping is why you don't want to carelessly
try to move them too soon while cleaning.)
Wash the sleeve in the same manner, you can eliminate a couple of the
cleaning steps as there is no finesse involved,. Finish though with soapy
water and blow dry and coat with lite oil. Both the piston assembly and the
sleeve should be immediately put into a plastic bag or sack to keep clean
and dust free until time of assembly. Remember each piston has it's own
sleeve and should not be changed out to another part.
Clean the ring compressor some before starting on the second piston
assembly.
When fitting to the engine just a lite oil on the rings and bore, finish
up and stand on the gas after about four or five minutes.
Done in this manner my rings lasted longer than any other method and
gave the best perforce all round.
I did make up a torquing plate for the dry blocks and did everything in
much the same manner. My torquing plate was made of 1" thick mild steel.
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