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Re: Flex-Hones

To: british-cars@autox.team.net, reilly@admail.fnal.gov
Subject: Re: Flex-Hones
From: sfisher@megatest.com (Scott Fisher)
Date: Tue, 24 May 1994 13:53:45 +0800
~ The real name for that tool is Flex-Hone, made by Brush Research Mfg. Co. of
~ Los Angeles (213-261-2193). 

Thank you; the joke name got tiresome after the fourth or fifth time I
typed it...

~ [. . .] but the gist of it seems to be that you want a
~ plateaued surface, mostly level with a few grooves in it for oil retention, 
~ but
~ no peaks sticking up above the plateau. Rigid hones give you cut, torn and
~ folded metal peaks on the surface (we're talking microinches here), which the
~ piston ring then has to break off. This is what breaking in or bedding in
~ really means. Using a flexhone does the same thing in a few seconds.
~ So I would use the flexhone even if you think the surface looks ok.

Additionally, list member Ernest Davis mentioned in private mail
that combustion can leave the surface of the bore with a glaze
that makes rings seat slowly, if at all, unless this glaze is broken.
For years, I've been reading about using flex-hones to "break the
glaze" prior to putting in new pistons, but Ernest was the first
person to explain what this glaze was from and why you need to 
remove it.

Now for the next topic: ring gaps.  Any tips or tricks on them?  I've
got a good quality file at home, plus all sorts of polishing stones
and sandpaper materials.  The manual describes how to set the rings
in the bore and measure the gap, and of course it has the actual
gap specifications.  Words of wisdom from anyone on that matter?  As
long as I'm buying a Flex-Hone (TM) and a piston ring compressing
tool, should I buy any proprietary ring gapping system?

Oh, and for the record, I'm using the '65-'70 connecting rods, from
18GB through 18GH, I think; they're the five-main version of the
angled big-end rods used on the three-main engine.  The rod bolts go
through the caps and screw into the rod itself; this, coupled with
the fact that the caps are split at a 45-degree angle to the rod
centerline and the metallurgy used in the rod bolts themselves, is
said to mean that you can reuse these rod bolts many times.  I'm
not taking any chances, however, as I've torqued them twice; it
costs $28 to get all new bolts, and that's only 10% of the parts
cost for THIS rebuild, which sounds like cheap insurance to me.  
And of course I'm using new locktab washers on the bolts as well. 

--Scott 


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