Date: Sun, 17 Nov 1996 08:49:24 +0000
From: Michael Moore
Assembling the bores basically dry (on the 1000cc BMW superbikes Udo Geitl would put just a drop of oil on each piston skirt) is a common practice, and does help the rings seat up. As soon as the engine starts and begins thrashing oil out of the big ends the cylinders will get plenty of lube. The dry condition doesn't last very long.
When I worked at a Suz/BMW/Tri dealership in Albuquerque in the early 70s a fellow named Phil York worked in the parts department with me one summer. Phil had set a Bonneville record on a Honda mini-trail with a nitro-burning S90 engine (just under 100 mph - Phil was pretty short - I sat on the bike and overhung both ends) and his buddy Dave Campos (a fairly big time drag racer) had talked him into building a Triumph drag bike. Phil told me that he assembled the rings on the pistons and then, with a very light honing paste of diatomaceous earth, would hand lap the rings in before assy. That way the fresh engine started out with seated rings.
Cheers,
Michael
Michael Moore
Euro Spares, SF CA
Date: Sun, 17 Nov 1996 09:07:16 -0500
From: Pete Serrino
At 01:50 PM 11/16/96 -0500, Stan Smith wrote:
>They advised him that, upon re-assembly, he should use no oil on the
pistons,
>cylinders, or rings. Just assemble them dry. He should, of course,
oil up the
>rockers before start-up. Has anyone heard of this method, or used
it
>successfully?
Norton guru, Leo Goff, suggested this method a few years ago at one of the Norton Nationals. I have used it twice (2 different Norton motors) had haven't experienced any ill effects. Leakdown on my current motor is <1% after 6K miles. I think a little oil on the skirts might be advised but no oil on the rings.
Pete
Date: Sun, 17 Nov 1996 10:17:00 -0600
From: John Goodpaster
>I guess the theory is that without lubrication in the bores, the rings
seat
>RIGHT NOW. Has anyone heard of this method, or used it successfully?
Everyone
>I have mentioned it to looks at me like I'm out of my mind! Have to
admit, I
>haven't personally tried it yet!
I have used this method for years. I also do this with arcft. engines. It doesn't take but several revolutions and you have oil splashed on the jugs. I think what is important is to drain the oil after an hour or so. This gets rid of a lot of the mini-swarf and fingerprints left on assembly.
This method is important if chrome rings are used as they are very hard and tend to glaze the walls if to slick to start with....................
AHRMA
Date: Sun, 17 Nov 1996 09:22:14 -0800 (PST)
From: Douglas Shook
It will be very hard for me to put an engine back together without the perfunctory hone, but I think I will try to do it. I just know that when I torque the head bolts down, it will be gnawing at me, though.
Just to calm my nerves, then, does it matter what type of rings you use? Should you adjust the end gap clearance specs to compensate? Any circumstances that one still would want to hone?
How did we all accept this fallacy (the need to hone) for so long? This one has hit me over the head like a 2x4.
==========
thank you,
shook
B50SS advocate
Date: Sun, 17 Nov 1996 09:51:34 -0800
From: kl and va fueston
Putting top ends together dry sounds terrible but actually works very well. In the late '60s I was hanging around C.R. Axtell's shop in Glendale and that was the way he did it. He said the boys at Offenhauser did it that way and that's where he found out about it. He would always specify that the machine shop bore the cylinder but not hone it. When it came back he used a coarse stone first then went in with a finer one and put a serious cross-hatch on it. At this time he was building the engines Gene Romero won #1 on. They went onto the dyno as soon as they were together and the only break in time they got was while the oil warmed up. As soon as they were at temperature it was 7000 rpm and full load. There was never a puff of smoke from pipe or breather and I don't believe they ever failed on the track in the two years he supplied engines.
I was sworn to secrecy at the time but after all these years it shouldn't matter.
I might mention he always used the timed breather, he felt that a timed
breather was far superior. If one is timed properly it should maintain
a low pressure in the crankcase at high rpm: this helps keep the oil downstairs
where it belongs. Regarding top end breathers he said "only the village
idiot would put a breather on top of an engine, the oil has enough trouble
finding it's way down the pushrod tubes without fighting the gases coming
up.
Vernon Fueston "Better a bottle in front of me,
Date: Fri, 15 Nov 1996 23:22:34 +0000
From: Robert Bickers
I'd only do that on a bet and then only if the wager were large enough to cover the damage if it didn't work. Rings will seat very quickly IF you apply full throttle in short bursts in mid RPM range then close throttle and use engine to slow you down, this pulls oil up and lubes/cools the rings. Honing has nothing to do with getting the rings to seat, it has all to do with closing the pores in the cast iron cylinder wall after boring. If these pores are not closed it will burn oil like crazy because the oil can set in the pores and bypass the rings, the rings will still seat and in about 30K miles the cylinders will be honed by the rings rubbing on them. I have born this out as well as had it confirmed by engineers from Seal Power.
Cheers
Date: Fri, 15 Nov 1996 17:17:18 -0800 (PST)
From: Douglas Shook
On Fri, 15 Nov 1996, Dominic wrote:
> I'm about to put new rings in my Triumph T140E and the manual states
that
> the bore should be checked (which I did) and cross hatched to remove
the
> glaze off the barrel walls.
Dominic,
Be certain that you use a decent inside micrometer checking at the top of the cylinder, fore and aft in particular. If it is within the re-ring specs, you can use a basic three stone bore honing attachment for your electric drill moving it up and down the bore swiftly to ensure the cross-hatch pattern (to retain oil when the piston is scraping against it). Don't grind any more material than you need to achieve the aforementioned cross-hatch.
I usually fit oversize rings and then grind the ends to ensure a proper end gap (you can use feeler gauges for this). There was a long discussion on ring gap spacing, but the general rule is at 120 degree intervals.
You'll also want to have a piston ring compressor for the re-assembly.
It sounds like you have been doing a major rebuild on the bike--good luck!
thank you,
shook B50SS advocate
Date: Sat, 16 Nov 1996 02:19:45 -0500
From: Mike Taglieri
>> I'm about to put new rings in my Triumph T140E and the manual states
that
>> the bore should be checked (which I did) and cross hatched to remove
the
>> glaze off the barrel walls.
I'm posting below a long essay by Pete Snidal last year explaining why honing a cylinder is unnecessary or even harmful unless you've boring it to the next size. I can't vouch for the truth of all this, but it convinced me.
Mike Taglieri
Raul -- '72 Commando Interstate
(original message reposted below)
-------------------------------------------
From: Peter Snidal
Date: Thu, 7 Sep 1995 12:47:46 -0700 (PDT)
Subject: Old Wives Tales. #1
Raul's Problem:
Definitely. Rip the top off and check things out. Immediately. After
all, it's not much of a chore, really - off with the pipes, the tank, the
carb(s), the head, and the barrels. Of course, putting it back together
is a bit more of a chore, what with trying to juggle all those four pushrods,
the head gasket, and the head all into place at the same time. Too bad
they didn't have the sense to use external pushrod tubes, so's you could
get the head bedded first, and then deal with the valve train later. Oh,
well, you could always find a Tri chopper, and let Raul finish his later
years as a Triton, I guess..... <g>
(Although why anybody would want a rubber Triton, I couldn't guess) Seriously, folks, I wanted to say a couple of things about boring, honing, ridge reaming, ring selection, etc.
OLD WIVE'S TALES REBUKED
Old Wives Tale #1: To Bore or Not To Bore:
It's not too bright to say, "bore the sucker while it's apart anyway."
There's only so many bores in a set of barrels, and pistons aren't cheap.
How you decide whether or not to bore is to check the clearances. Also,
check the size of the piston itself, and interior mike the bores. If the
bores are straight, and even if you have excessive clearance, but the clearance
is due mostly to piston wear, (being aluminium, surprise, surprise, they
wear much faster than the cast iron cylinders) you can often just replace
the old pistons with new ones, and not bother with the bore job. Why use
up an oversize on a perfectly good cylinder if you don't have to? I have
personally put fresh pistons in old cylinders with good results many times.
Clearance is the key here.
Now, let me blow a few minds over honing:
I was once in attendance at an Auto Mechanics course at Technical College, dancing thru the hoops for a degree in Industrial Ed. One topic we kicked to death in there was the subject of honing and ridge reaming cylinders. It all came about when the instructor greeted us one morning with the news that you should *never* hone cylinders except to finish a bore job, and that it's *pointless* to ream ridges, unless you need to get the piston out. (Cars)
What an uproar! Most of us had had a fair amount of experience with engines, and we were pretty incensed. You *have* to "deglaze," or the rings will never seat! You *have* to deridge, or the new rings will hit the ridge and break on the first stroke! Everybody knows that!
Well, our instructor, who was a pretty savvy guy, knocked the wind out of the sails of the more scientifically inclined among us with one move: he handed out some reprints of actual SAE test results involving deglazing/not deglazing rering jobs, and ditto for ridge reams. It seemed that the compression test figures after 10000 miles were *better* by far for the unhoned engines. Also the increases in piston clearance were less, as was the bore wear, and - get this - they also showed *significantly* less bearing wear.
How come? Well, it seems that when you scuff up a perfectly good smooth cylinder with a rude sort of carborundum device, you are in fact only putting scratches on it, giving us a new, larger diameter at their base - sort of like root and pitch diameters in a nut, say. And when you put it back together, the new rings and this rough surface proceed to grind each other down until smoothness is re-attained. By this time, needless to say, you have larger ring gaps, due to more ring wear, and more piston clearance, since the cylinder has been taken down now to the base diameter of the honing scratches. And the valuable metal so removed has been converted into grinding compound circulating in your oil, so you have also reduced the size of your piston, and contributed significantly to wear of all the other parts as well, from rocker bearings to cam bearings to timing chain rollers to rods and mains.
Proven. Scientifically demonstrated in an actual SAE sponsored research
project. But you gotta *deglaze* or the rings will never seat, correct?
Well, yes and no, Chet. Although it is true that *chrome* rings are so
hard and smooth that it can take from a long time to forever for the cylinder
to wear them to perfect fit, this is *not* the case for Cast Iron rings.
In fact, that's the secret. Chrome rings only in rough (honed) bores. And
hone bores only when you have to, ie as the final "finish" of a bore job.
Since the boring bar tool in effect runs a screw thread down the bore in
its journey toward the land of largerness, it is necessary to do a final
"polish" with a somewhat cruder tool - the hone. This is the *only* reason
to put a hone in a cylinder. And when it's done, the machinist has purposely
left some extra meat in there for the hone to finish to final diameter.
And the final diameter is a tad small as well, in anticipation of the initially
rapid wear that is inevitable as the new rings and the scratchy bore get
acquainted. This is also the reason for very careful cleaning of said bores
before assembly, and for very frequent oil and filter changes, until the
motor has stopped manufacturing grinding compound during the
break-in process.
Back to re-ring jobs. Turns out there is just plain no reason to muck up that lovely smooth bore with a hone. None. Cast Iron rings will seat just fine on a smooth bore. And wear a lot less in the process. Ditto for the bore. So check the clearances, select the new pistons option if you like, and be sure to use Cast Iron rings. But don't subject your engine to a bearing grind job just because your mom always told you to hone your bores. It's silly.
I imagine this will shake up a few readers of brit-iron. I know it shook up me and my classmates that fateful day in '69. But I rebuilt my 544 Volvo in that class that year, and followed the prof's advice. And it seated its rings just fine, in a few hundred miles. And I haven't honed a cylinder on anything since - probably 30 or 40 rebuilds later.
And I've never had rings fail to seat. And I know all those engines lasted longer than they otherwise would have. In fact, I put 117,000 miles on a 235 Chevyvan rebuilt this way. The van was into its 200K range when I did @and it burnt no oil (<1qt/1000) when it finally rusted its way to the big Toyota factory in the sky.
I could tell you of lots of others, but that's sufficient, I think. Trust me - Throw Away That Hone. Unless, of course, you're Boring. (tee hee)
Next Week: Old Wives Tale #2: Reaming Ridges Bites It
(Anyone care to conjecture?)
Date: Sat, 16 Nov 1996 13:50:05 -0500
From: Stan Smith
Mike Taglieri posted a message by Peter Snidal about honing, which, I am sure, will spawn endless (interesting) debate amongst this group. I would like to throw another monkey wrench in to the gearbox by relaying some information from a friend who had some top end work done on his 1000cc BMW by a certain Left Coast dealer. They advised him that, upon re-assembly, he should use no oil on the pistons, cylinders, or rings. Just assemble them dry. He should, of course, oil up the rockers before start-up. These cylinders had been honed and new pistons & rings were going in. He did what they told him, and the bike has never used a drop of oil since the rebuild. I guess the theory is that without lubrication in the bores, the rings seat RIGHT NOW. Has anyone heard of this method, or used it successfully? Everyone I have mentioned it to looks at me like I'm out of my mind! Have to admit, I haven't personally tried it yet!
Stan Smith