Today's Message Index:
----------------------
1. 04:00 AM - Re: Balancing Connecting Rods (Hopperdhh@aol.com)
2. 04:00 AM - Re: Balancing Connecting Rods (Hopperdhh@aol.com)
3. 05:22 AM - Re: Balancing Connecting Rods (Hopperdhh@aol.com)
4. 05:22 AM - Re: Malpassi fuel pressure regulators (Gilles Thesee)
5. 06:06 AM - Re: Balancing Connecting Rods (Archie)
6. 11:21 AM - Re: Balancing Connecting Rods (Hopperdhh@aol.com)
7. 06:40 PM - Re: Balancing Connecting Rods (Red Hamilton)
Message 1
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: Hopperdhh@aol.com
Archie,
I have been giving this balancing problem a lot of thought. I am used to
thinking race car engines -- V8s with a 4 plane crank. In that case it is of
course necessary to match up all the rods and counterweight the crank while
balancing it. It occurs to me that if all the unbalance (imbalance?) is in a
single plane -- say the small ends of the rods match but the big ends don't,
then a 4 cylinder engine CAN be brought into balance by just adding weight at
the front end. That is, that balancing the prop does correct for imbalance
even at the back of the shaft. Therefore it is not necessary to balance the
big ends of the rods if you do a dynamic balance of the prop after the engine
is installed on the airplane.
What do you think?
Dan Hopper
RV-7A Flying -- working on another engine
Message 2
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: Hopperdhh@aol.com
In a message dated 3/5/2006 10:31:21 P.M. Eastern Standard Time,
redswing@mcn.org writes:
Prior to starting, you may want to check the bore accuracy.
This is a great suggestion. Aircraft rods are sometimes returned to service
in unserviceable condition because many of the shops do not edven check the
big end bores. If your heavy rod(s) also need to have the big end bore
resized, that could fix both problems at the same time.
Red Hamilton
I almost missed this comment embedded in Archie's text. That is a great
suggestion, Red. I'll bring it up as a possibility with the shop doing the
balancing. Also, see my other post on why it may not even be necessary to
balance the big ends.
Dan Hopper
Walton, IN
RV-7A Flying since July 2004 -- Building up another engine for a spare, or
something!
Message 3
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: Hopperdhh@aol.com
Archie and listers,
Sorry to reply to my own post! Please disregard the attached earlier post.
I didn't have my brain fully engaged yet this morning!
Even when balancing a wheel (with width), you have to be able to get to both
ends in order to bring it into dynamic balance. A crankshaft is no
different in this regard. So therefore it is important to match up all the rod
big
ends.
Dan
In a message dated 3/6/2006 7:02:51 A.M. Eastern Standard Time,
Hopperdhh@aol.com writes:
--> Engines-List message posted by: Hopperdhh@aol.com
Archie,
I have been giving this balancing problem a lot of thought. I am used to
thinking race car engines -- V8s with a 4 plane crank. In that case it is
of
course necessary to match up all the rods and counterweight the crank while
balancing it. It occurs to me that if all the unbalance (imbalance?) is in
a
single plane -- say the small ends of the rods match but the big ends
don't,
then a 4 cylinder engine CAN be brought into balance by just adding weight
at
the front end. That is, that balancing the prop does correct for imbalance
even at the back of the shaft. Therefore it is not necessary to balance
the
big ends of the rods if you do a dynamic balance of the prop after the
engine
is installed on the airplane.
What do you think?
Dan Hopper
RV-7A Flying -- working on another engine
Message 4
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| Subject: | Re: Malpassi fuel pressure regulators |
--> Engines-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Jan de Jong a crit :
>--> Engines-List message posted by: Jan de Jong <jan.de.jong@xs4all.nl>
>
>Hello Gilles,
>
>I found:
>http://www.officinamalpassi.it/
>There are 8 models for carburetor / turbo.
>Unfortunately no specifications: "*Descrizione tecnica:* Non disponibile".
>
>
>
Jan,
Great ! Thanks for the link.
I had skipped that one when Googling...
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
Message 5
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
On V-8 engines, the total weight of the rotating end is incorporated
in the formula for bob weight setup, and only 50% of reciprocating weight.
(which also includes, Piston, Pin, and Rings.
This basic formula can be modified for over or under balance,
but is beyond the scope of conversation here.
When a crankshaft is being corrected, it is not only balanced rotationally,
but also end to end. AKA "COUPLE".
BTW, most of my work is in racing engines.
Archie
> --> Engines-List message posted by: Hopperdhh@aol.com
>
> Archie,
>
> I have been giving this balancing problem a lot of thought. I am used to
> thinking race car engines -- V8s with a 4 plane crank. In that case it
> is of
> course necessary to match up all the rods and counterweight the crank
> while
> balancing it. It occurs to me that if all the unbalance (imbalance?) is
> in a
> single plane -- say the small ends of the rods match but the big ends
> don't,
> then a 4 cylinder engine CAN be brought into balance by just adding
> weight at
> the front end. That is, that balancing the prop does correct for
> imbalance
> even at the back of the shaft. Therefore it is not necessary to balance
> the
> big ends of the rods if you do a dynamic balance of the prop after the
> engine
> is installed on the airplane.
>
> What do you think?
>
> Dan Hopper
> RV-7A Flying -- working on another engine
>
>
>
Message 6
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: Hopperdhh@aol.com
Archie,
You're preaching to the choir here! I have built quite a few V8 race
engines in my day. My racing days are over, though. I have made engine balance
a
hobby and have studied it quite a bit. I once decided to become an expert on
vibration and balancing, but found that it was a much more complicated field
than I had imagined. Fortunately, most engine work we do does not require
exact knowledge, and the 100 percent rotating and 50 percent reciprocating
formula is as close as we need to be. Well, again that was back in my day.
That was the late 60's and early 70's. I don't know about the latest engines.
I built many engines that way back then. Yes, I understand that symmetrical
cranks like 4 cyl and 6 cyl don't need bob weights during balancing.
I called Aircraft Specialties Service this morning, and I think that they
are going to work with me on getting a closer set of rods than I have now.
Thanks again for the advice,
do not archive
Dan Hopper
RV-7A
Walton IN
In a message dated 3/6/2006 9:07:20 A.M. Eastern Standard Time,
archie97@earthlink.net writes:
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
On V-8 engines, the total weight of the rotating end is incorporated
in the formula for bob weight setup, and only 50% of reciprocating weight.
(which also includes, Piston, Pin, and Rings.
This basic formula can be modified for over or under balance,
but is beyond the scope of conversation here.
When a crankshaft is being corrected, it is not only balanced rotationally,
but also end to end. AKA "COUPLE".
BTW, most of my work is in racing engines.
Archie
Message 7
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| Subject: | Re: Balancing Connecting Rods |
--> Engines-List message posted by: "Red Hamilton" <redswing@mcn.org>
Sorry, I had it in a contrasting color--that got stripped.
Red
----- Original Message -----
From: Hopperdhh@aol.com
To: engines-list@matronics.com
Sent: Monday, March 06, 2006 3:59 AM
Subject: Re: Engines-List: Balancing Connecting Rods
--> Engines-List message posted by: Hopperdhh@aol.com
In a message dated 3/5/2006 10:31:21 P.M. Eastern Standard Time,
redswing@mcn.org writes:
Prior to starting, you may want to check the bore accuracy.
This is a great suggestion. Aircraft rods are sometimes returned to service
in unserviceable condition because many of the shops do not edven check the
big end bores. If your heavy rod(s) also need to have the big end bore
resized, that could fix both problems at the same time.
Red Hamilton
I almost missed this comment embedded in Archie's text. That is a great
suggestion, Red. I'll bring it up as a possibility with the shop doing the
balancing. Also, see my other post on why it may not even be necessary to
balance the big ends.
Dan Hopper
Walton, IN
RV-7A Flying since July 2004 -- Building up another engine for a spare, or
something!
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