Today's Message Index:
----------------------
1. 03:18 AM - Connecting rod/bolt balancing questions (Hopperdhh@aol.com)
2. 04:27 AM - Re: Connecting rod/bolt balancing questions (Archie)
3. 06:39 AM - Re: Connecting rod/bolt balancing questions (Hopperdhh@aol.com)
4. 07:25 PM - Re: Connecting rod/bolt balancing questions (Archie)
Message 1
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| Subject: | Connecting rod/bolt balancing questions |
--> Engines-List message posted by: Hopperdhh@aol.com
I am in the middle of overhauling a Lycoming IO-360-A1A for my RV-7A. It
has come to my attention that there are 2 different rod bolts that will work in
the LW10646 connecting rods. One has a small head and a later bolt has a
larger head.
First question -- Is there anything wrong with using the small headed bolt
(these are the ones I bought from Aircraft Specialties about a year ago)
PN75060?
Second question -- What is the weight difference between the two bolts?
I have weighed the rods (big ends and small ends), and could possibly use
the heavier bolts to get a better matching set to improve the engine balance.
Speaking of engine balance, what is considered good enough? Is 6 grams at
the big end of the rods really bad, or good, or what? It looks like I have
about 3 grams worst case on the recip end. The crank is good (under 1 gram),
and the piston/pins are only a couple of tenths apart.
Thanks,
Dan Hopper
Walton, IN
RV-7A N766DH Flying 144 hours.
Message 2
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| Subject: | Re: Connecting rod/bolt balancing questions |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
Balance criteria on any component is dependent on application parameters.
I personally maintain 1/5 of a gram on statics, and .01 in/oz on dynamics
(or better), for aircraft. Racing engines better than that.
Why not? If you are there working anyway, why not do the best, or close to
it?
(a dollar bill weighs one gram)
Archie
---- Original Message -----
From: <Hopperdhh@aol.com>
Sent: Saturday, March 18, 2006 6:14 AM
Subject: Engines-List: Connecting rod/bolt balancing questions
> --> Engines-List message posted by: Hopperdhh@aol.com
>
>
> I am in the middle of overhauling a Lycoming IO-360-A1A for my RV-7A. It
> has come to my attention that there are 2 different rod bolts that will
> work in
> the LW10646 connecting rods. One has a small head and a later bolt has a
> larger head.
>
> First question -- Is there anything wrong with using the small headed bolt
> (these are the ones I bought from Aircraft Specialties about a year ago)
> PN75060?
>
> Second question -- What is the weight difference between the two bolts?
>
> I have weighed the rods (big ends and small ends), and could possibly use
> the heavier bolts to get a better matching set to improve the engine
> balance.
>
> Speaking of engine balance, what is considered good enough? Is 6 grams
> at
> the big end of the rods really bad, or good, or what? It looks like I
> have
> about 3 grams worst case on the recip end. The crank is good (under 1
> gram),
> and the piston/pins are only a couple of tenths apart.
>
> Thanks,
>
> Dan Hopper
> Walton, IN
> RV-7A N766DH Flying 144 hours.
>
>
>
Message 3
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| Subject: | Re: Connecting rod/bolt balancing questions |
--> Engines-List message posted by: Hopperdhh@aol.com
Archie,
I took the rods to a shop to be weighed. I didn't want them to remove any
metal until I had a chance to analyze the weights. Actually, I didn't want to
risk the damage they could do! I don't have the equipment or facilities to
do the job myself, or I would do as you say. Since they were much, much
worse than the values you gave, I wonder if there is really anything to be gained
by getting so "perfect." I overhauled a Continental O-200 a few years ago
and got a very smooth running engine by putting the heavier parts opposite
each other, and matching heavy rods with lighter pistons, etc. The final
assembly was not near as close as you would have done. The Continental Overhaul
Manual states that pistons opposite each other should be within 1/2 ounce --
that's about 14 grams.
I know that you will say to send the rods out to be balanced, but I still
want an answer to my original question from those who know from experience. I
once read that "good enough is perfect." Being a perfectionist myself, I
often have to use that philosophy to move projects along.
Thanks,
Dan
In a message dated 3/18/2006 7:28:24 A.M. Eastern Standard Time, arc
hie97@earthlink.net writes:
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
Balance criteria on any component is dependent on application parameters.
I personally maintain 1/5 of a gram on statics, and .01 in/oz on dynamics
(or better), for aircraft. Racing engines better than that.
Why not? If you are there working anyway, why not do the best, or close to
it?
(a dollar bill weighs one gram)
Archie
Message 4
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| Subject: | Re: Connecting rod/bolt balancing questions |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
As you indicate, it is better to spend a little time and money now,
than to wish you had.
There is no substitute for perfection........... None!
The factory recommends 1/2 ounce?
Well, keep in mind these are the same people that give us oil burners,
AD's on an engine that has not changed for over 60 years, 1/2 hp per cu. in.
And they still do not have it right.
They essentially have a captive following that buys this.
If they did not have that, they would have folded long ago.
How would you like to be buying a new car and the salesperson told you
you must run plug gaps of .016 because magnetos will not support more,
It will burn oil, Is subject to AD's which you will forever pay for,
Has poor fuel economy, Blow-by, and 1/2 hp per cu in?
Would you find these attractive? Would you buy this car?
If a small hole in the wall shop like mine can correct most of these,
why can't they? Why do they have engineering if the most basic of problems
have not been corrected? Bean counters tend to run these companies, and
quality, plus R&D have fallen dormant.
I have somewhat evaded a succinct reply to your last post, but am thoroughly
miffed with the beaurocratic ineptitude, greed, and propagandists that seem
to be the root culprit hampering any progress.
Sorry about the long wind, but I have only started, and will quit now
to cool off.
==================================================
> I took the rods to a shop to be weighed. I didn't want them to remove
> any
> metal until I had a chance to analyze the weights. Actually, I didn't
> want to
> risk the damage they could do! I don't have the equipment or facilities
> to
> do the job myself, or I would do as you say. Since they were much, much
> worse than the values you gave, I wonder if there is really anything to
> be gained
> by getting so "perfect." I overhauled a Continental O-200 a few years
> ago
> and got a very smooth running engine by putting the heavier parts
> opposite
> each other, and matching heavy rods with lighter pistons, etc. The final
> assembly was not near as close as you would have done. The Continental
> Overhaul
> Manual states that pistons opposite each other should be within 1/2
> ounce --
> that's about 14 grams.
>
> I know that you will say to send the rods out to be balanced, but I still
> want an answer to my original question from those who know from
> experience. I
> once read that "good enough is perfect." Being a perfectionist myself, I
> often have to use that philosophy to move projects along.
>
> Thanks,
> Dan
>
>
> In a message dated 3/18/2006 7:28:24 A.M. Eastern Standard Time, arc
> hie97@earthlink.net writes:
>
> --> Engines-List message posted by: "Archie" <archie97@earthlink.net>
>
> Balance criteria on any component is dependent on application parameters.
> I personally maintain 1/5 of a gram on statics, and .01 in/oz on dynamics
> (or better), for aircraft. Racing engines better than that.
> Why not? If you are there working anyway, why not do the best, or close
> to
> it?
> (a dollar bill weighs one gram)
> Archie
>
>
>
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