Crankshaft balance

Abripl,

I lost the messages that began this thread so I forget whether you had a 4
or 6 cyl. I also do not remember if I asked you about your prop position.

I stopped by Aircraft Specialties Services today. I looked at several
Franklin cranks and some rods.

Anyway, for one source, if you decide to send your crank and rods off for
balancing, talk to Harold or Bobby at A/c Spec. 800--826-9252
$115 for the crank balance and about $45 for the rods.


If you have any questions which I can help you with, you are welcome to
email me directly.

The bigotry expressed by others in this thread is bordering on getting
personal. I am going back to lurk mode.

good luck
Kent Felkins



"abripl" wrote in message
ups.com...
Here is some more discussion about balancing:

http://groups.google.com/group/rec.a...9345c98a2408b1

ah ... those dastardly engines!


http://www.ntsb.gov/ntsb/brief.asp?e...19X00071&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...12X22244&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...12X21584&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...12X18865&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...05X00509&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...05X00196&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...11X10959&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...18X01860&key=1

http://www.ntsb.gov/ntsb/brief.asp?e...04X01567&key=1

Anyway, for one source, if you decide to send your crank and rods
off for
balancing, talk to Harold or Bobby at A/c Spec. 800--826-9252
$115 for the crank balance and about $45 for the rods.


If you have any questions which I can help you with, you are welcome to

email me directly.


The bigotry expressed by others in this thread is bordering on getting
personal. I am going back to lurk mode.


good luck
Kent Felkins



"abripl" wrote in message


Bigotry ???????? Hmmmmm. And I thought this was the rec.aviation.
"homebuilt" list? Of course we are suspect of the feds silly rules.
Look at their track record.. After all they are only 7 TRILLION dollars
in debt.

One more thing, if this is the Bobby I have heard of ,you better mark
your crank in a discreet place because he has been known to swap
customers good cranks for ones he has laying around that are of "lesser
quality". That way he can resell your good one and make a nice profit
and you get back a P.O.S.....

Happy Flying...

Ben,

I got a word from the machine shop. They say they can balance the crank
- about 5 g off on one end and about 8 g on other end. But they are
worried about the pistons and rods. Pistons about 5 g off and some rods
about 5 + 3 off. They will try to do the best but cannot take that much
alum off the pistons.

... make some hard, expensive choices.... or live with .. part....

They will get it as close as they can. The engine was about .4 ips
imbalanced to start with - not so terrible, FAA certified limit is 0.2
ips. Any improvement will certainly help and may bring it within the
0.2 ips. Remember that this engine redlines at 2800rpm compared to an
auto engine at about 6000rpm. The same mass imbalance forces are one
quarter that of an auto engine.

There are some tricks that can be done:
A.) for heavy rods big end - cut off four of the six castle nut crowns
to save almost 2 g or use a longer heavier nut with a slot where the
cotter pin goes to add 2 g to light big ends = a difference of 4 g.
B.) We will also look at matching light pistons with heavy small ends
and heavy pistons with light small end.

My engine is listed as EXPR-OTHER and not as not as a certified
Franklin - required 40 hours test time. This allows using a little
ingenuity to solve such problems.

"abripl" wrote in message
oups.com...
Ben,

I got a word from the machine shop. They say they can balance the crank
- about 5 g off on one end and about 8 g on other end. But they are
worried about the pistons and rods. Pistons about 5 g off and some rods
about 5 + 3 off. They will try to do the best but cannot take that much
alum off the pistons.

It sounds like you are about to make some hard, expensive choices. New
pistons and rods, or live with at least part of it, is what it sounds like,
to me.

That is a lot of difference, don't you think?
--
Jim in NC

"
"abripl" wrote in message
One more thing, if this is the Bobby I have heard of ,you better mark
your crank in a discreet place because he has been known to swap
customers good cranks for ones he has laying around that are of "lesser
quality". That way he can resell your good one and make a nice profit
and you get back a P.O.S.....

I said I was going back to lurking, but I am coming back to this slop
trough for one more post.

I've watched this group for over ten years and occassionally have seen a
contributor who is sharp and experienced in their field and is willing to
relate their knowledge. Its like finding a diamond's in a goat's butt.
Other times though I just find a goat's butt.

This thread started out about some guy writing about franklin engine
vibration and crankshaft balance. I joined in to offer my opinion from my
18 or so years experience in the field.
And I get bashed for being FAA certified.
Then I infer I was could bring to this thread the experience of a
nationally known and well-respected firm who actually does the work on the
said type of crankshaft and connecting rods.
And somebody says the firm is a crook and rips off their customers.

The firm I am talking about has been in the business for close to 30
years and is still thriving and expanding. My business is thriving
too. You don't achieve that by ripping people off.

Parts trading is well known trick in in many fields. And savy people know
it.
And anyone savy knows aircraft cranks have discreet marks to begin with.

Whoever the Bobby you're thinking of must be some p.o.s working in the auto
shop in Jackson.

I could care less

Kent Felkins
Tulsa

"Fly" felk AT gbronline.com wrote

Parts trading is well known trick in in many fields. And savy people
know
it.
And anyone savy knows aircraft cranks have discreet marks to begin with.

Whoever the Bobby you're thinking of must be some p.o.s working in the
auto
shop in Jackson.

I could care less

Kent Felkins

Obviously, you could care less, or you would not have posted a rebuttal. He
may be correct, or may be incorrect. I did notice that you did a very nice
job of turning it around to slam someone else, however.

I don't know you from a hole in the ground. I'm glad you think you work in
a good shop. You would not be working in my shop, if you did not think
where you were working was a good place. Good for you.

That said, "my" opinion of what got you "rubbed the wrong way" was your
attitude that your way was the only way, and that because you worked on
aircraft engines, no one else might be capable of doing as good a job, or
better.

Around where I live, there are racing engine shops everywhere. They feed
the racing market with engines that up and coming future stars in the auto
racing world use. While you attempt to build engines that are reliable,
they only have to be reliable at very modest power levels. The
displacements of an aircraft engine that put out 200 HP, are putting out
over 750 HP in the racing world. They do so at the expense of a long life,
but they are very reliable in that designed life span. They strive to get
just a couple more HP, or a smoother engine, or one that will have better
fuel economy to beat their competition. They innovate, and experiment, and
develop things that are incorporated into future mass produced engine
designs.

All the while, you are rebuilding 1930's engines, with precious few
innovations. I'm glad someone is doing it, and doing it well. Don't be
offended when someone else says they are capable of doing it as good, or
better. Some may be able to do just that.

To think that these engine builders don't have some tricks that you are not
interested in, or allowed to do by the FAA, or capable of performing that
results in making a smoother running engine is extremely smug of you. I
have no doubt that some may be able to do some things your shop has never
even dreamed of.

The person posting got some technical details wrong, but so what. He is not
the racing engine rebuilder. They are out there, and do quite well, thank
you. You would do well to acknowledge the fact that others do know their
craft, and have pride in it, just as you do.

Feel free to jump in and offer advise, and opinions about subjects you are
well versed in. No doubt, you have a lot to offer this group.

The most valued members come here with humility, and knowledge, but enter
into discussions with the idea that they may find someone who knows as much
or more. There is always someone out there smarter than yourself. (or
myself)

With that, is the fact that some do not know when to shut up, or when to not
flame. Those are the pitfalls of a public forum. Thick skins are required.

soapbox = off.
--
Jim (Morgan) in NC

OK. They managed to get things in balance - within one gram.
The only thing was the starter gear with the torsional damper. Because
of the fluid damper it changes - about 5g out max. Does anybody know if
5g is acceptable for a 10" flywheel?

OK. They managed to get things in balance - within one gram.
The only thing was the starter gear with the torsional damper. Because
of the fluid damper it changes - about 5g out max. Does anybody know if

5g is acceptable for a 10" flywheel?



////////////////////////////////////////////

One gram is darn close for your application. You will notice a
difference when ya fire up the new beast. As for the damper, if it is a
fluid style i can tell you they never repeat while spinning up on a
balancer machine. Temp differences cause the viscious fluid to migrate
differently every time so don't sweat the small numbers there. I am
curiuos, Was this engine a first time run motor and never been into
before? You would think with all the FAA requirments they would dictate
part weights in a new "certified" motor to be closer then 5-8 grams.
I also want to say Jim was very good at reading into the fine print and
giving a great feel of what was trying to be said. I am a little
forward in expressing my views and do sometimes rub people the wrong
way and hope we can get over this feud.

Happy Hollidays all you guys.

Ben