Procedure for breaking in iron-moly rings

[Keith or M.A. Carlson]

For my engine build, some have suggested iron-moly piston rings would be
the ultimate, others say they are very difficult, if not impossible, to
get seated in, and say I should stick to plain iron rings.

Is there a trick to getting iron-moly rings to seat properly in
break-in??

TIA
Keith C.
--
A little nonsense now and then
is relished by the wisest men.
======================================
Keith or Mary Ann Carlson
Minneapolis, Minnesota
kcar...@citilink.com

[N. Nelson]

In article <378193...@citilink.com>, "Keith or M.A. Carlson"
<kcar...@citilink.com> wrote:

There is no real trick to getting Moly rings to seat as long as the proper
cylinder wall finish is used. Since the Moly coating holds oil, the
cylinder wall finish needs to be rather smooth, unlike when chrome rings
are used and a rough finish is desired. Moly rings do not tolerate dirt,
so keeping the intake air clean is important. The general rule for Moly
rings is a finish hone to size using a #280 grit stone, you are after a
finish somewhere between 16-23 RA. If using a diamond hone, a 500-550
grit should yield a finish around 13-15 RA......
the actual results vary between equipment (hone) manufacturers, finish up
with about 8-10 strokes with a plateau honing tool. Your machinist should
be able to make the correct choice for the ring application that you have
choosen.
When assembling the engine, do not use to heavy of an oil when installing
the piston/rings assy. 10W30 is fine.....some shops like to use ATF (high
detergent) to help float the initial wearin particles to the surface
(first few revolutions.
For initial start up, make certain that the cooling system is full and
burped of any air, timing is set, oiling system is primed and the carb or
fuel injection is primed....extended cranking is badfor proper break in.
If the machinist does his job correctly, the rings will break in before
the cam and lifters do.
The engines I have built using Speed Pro or Perfect Circle Molly ring sets
have less then 10% leakage after the initial 20 minute break in at 2000
RPM, this improves to around 6% after 1000 miles.

Good luck with your re-build....

--
Neil Nelson
***********************************
Send Lawyers Guns and Money,
The shit has hit the fan. WZ
***********************************

[RDM]

    I agree with all that Dan has said. I do want to elaborate a little more on the cylinder wall finish, though. According to Scott Gabrielson (ring design engineer for Federal-Mogul) A two stage honing process is what is recommended. Beginning with a #220 or #280 grit stone (as Dan mentioned), hone to within .0005 of the final size and then polish the bores with a #400 grit stone or a flexible abrasive brush in order to plateau the surface. The following is a quote...."This procedure can produce a bore surface with plenty of bearing area to support the rings, adequate crosshatch to hold oil for ring lubrication, and no sharp peaks to wear the new rings. A plateau finish also provides an instant seal to minimize blowby and ring break-in."
    This information comes from Automotive Rebuilder, one of the many trade magazines that I receive. And, the one that I "devour" every month. This one happens to be the Dec. 1998 edition. If anybody is interested, you can go to www.ncbuy.com to check out more about this magazine.
    Hope that all of the info you are getting helps!

Later
Rich
 

[Keith or M.A. Carlson]

Yes, thanks! The responses have been very helpful.

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