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  #21  
Old 10-27-2015, 09:48 AM
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bret bret is offline
 
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I agree Mel, to a certain extent, imagine a little weight at the small end of a rod, and then that gets matched up to one of the heavy pistons, and then gets thrown on the heavy crank journal, all those little grams add up, the way I have seen it done is, all pistons milled down to lightest piston, all rods get balanced big and small ends, bob weight of rod bearings, rods, wrist pin, retainers, pistons and rings, rod bearing oil amount, flywheel, HB get mounted to crank and dynamically balanced by adding Mallory or drilling counter weights, not that expensive in the scheme of things.
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  #22  
Old 10-27-2015, 09:59 AM
F1R F1R is offline
 
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Default Into Building Crazy Big Blocks are we?

So why not try an LS1 small block like this

https://youtu.be/PP2bJcu85ho

Or an LS 6 454 big block for a few extra pounds ?

https://youtu.be/4uao4lJrwnk

Last edited by F1R : 10-27-2015 at 10:04 AM.
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  #23  
Old 10-27-2015, 10:30 AM
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Quote:
Originally Posted by bret View Post
I agree Mel, to a certain extent, imagine a little weight at the small end of a rod, and then that gets matched up to one of the heavy pistons, and then gets thrown on the heavy crank journal, all those little grams add up, the way I have seen it done is, all pistons milled down to lightest piston, all rods get balanced big and small ends, bob weight of rod bearings, rods, wrist pin, retainers, pistons and rings, rod bearing oil amount, flywheel, HB get mounted to crank and dynamically balanced by adding Mallory or drilling counter weights, not that expensive in the scheme of things.
True. The way I balanced mine was to balance the piston/rod assembly as a unit.
My point is that you don't need to balance to 1/10 gram. If I remember correctly, Lycoming's limit is something on the order of 7 grams between the heaviest and lightest assembly. If you get to within a gram, that's a pretty good balance.
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  #24  
Old 10-27-2015, 10:30 AM
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Well....I've done a few V8 Pinto and Vega 1/4 mile cars, even a turbo V8 Detroit 8.2 diesel+Allison in a pickup, but I think Ill stick to airplane engines in airplanes....for now....
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  #25  
Old 10-27-2015, 02:38 PM
Allen Barrett Allen Barrett is offline
 
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Default balancing your mass

PLEASE don't drill on your crankshaft. PLEASE!!Or you'll be buying another one.
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  #26  
Old 10-27-2015, 05:43 PM
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See! constructive criticism! I won't drill my crank. thanks, as you re read my first post, first sentence, I have no aircraft engine experience, But, I still want to build my own engine. I am getting a feeling that this is one big secret or maybe there is not that much info to be gathered here, or, maybe folks are afraid to give advice in fear of a lawsuit? I see some have stated that they are not responsible for any advice given, is that a problem here, just asking....... here is one example of a Lycoming improvement. how many folks have this improvement, and how many do not? I'm sure there are many improvements out there but not much interest? https://www.youtube.com/watch?v=QDnPOE5lGEE
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  #27  
Old 10-27-2015, 05:54 PM
Kyle Boatright Kyle Boatright is offline
 
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I found rebuilding my engine to be very simple following the instructions of two A&P friends and the Lycoming manual. That said, it is procedural in that you must be disciplined enough to make sure it goes together properly. You have to verify a number of measurements, assemble things in the correct order, use the appropriate sealants/lubricants for the specific applications, etc. Still, it is not rocket science.

If you do have a desire to build your own engine, I think your best bet is to find an experienced local engine builder and have him supervise your work. That way, you do the work, but know that the engine was assembled properly.
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  #28  
Old 10-27-2015, 06:37 PM
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N941WR N941WR is offline
 
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Bret, you are asking the right questions. Like you, I too had built up a number of engines before the one I currently fly behind but none of those were aircraft engines.

What I did was to find an IA who helped me put my engine together. Taking the engine apart and sending the pieces out for inspection takes a lot of time and will be a big savings, if you do that yourself.

I was stunned at the number of different lubricants and sealants needed for the assembly. Heck, even finding the silk thread was a challenge.

Quote:
Originally Posted by bret View Post
My last crazy big block I built, I watched my machine shop ( who specializes in race engines ) balance the rotating assembly within 1 10th of a gram, not rocket science here.
The problem with balancing the moving parts on an aircraft engine is you just can't take them to a grinding wheel or drill holes in them, like you might do on an auto engine. I know of one IO-540 that was "built up" by a known aircraft race builder and when a more reputable builder took it apart to inspect something, they found the guy had just run the connecting rods on a bench grinder. Pretty much the entire engine was trashed by the "expert".

While our engines are low speed engines, they are high torque, and that can snap parts.
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  #29  
Old 10-27-2015, 06:55 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by bret View Post
See! constructive criticism! I won't drill my crank. thanks, as you re read my first post, first sentence, I have no aircraft engine experience, But, I still want to build my own engine. I am getting a feeling that this is one big secret or maybe there is not that much info to be gathered here, or, maybe folks are afraid to give advice in fear of a lawsuit? I see some have stated that they are not responsible for any advice given, is that a problem here, just asking....... here is one example of a Lycoming improvement. how many folks have this improvement, and how many do not? I'm sure there are many improvements out there but not much interest? https://www.youtube.com/watch?v=QDnPOE5lGEE
I, for one, am not trying to keep anything secret. But I remember a number of spots during an engine build with a master builder where he said "now the trick here is...." The problem is - I don't remember those tips - so I can't share them with you. Not because I don't want to. I don't build these engines all the time - maybe once a decade. I don't stay sharp flying a particular complex airplane if I don't look at it or touch it for ten years - and engine building (as has been said) is very procedural, just liek flying with complex systems.

The toher thign to rememerb is that if you mess up building a fire-breathing Chevy with lots of mods for your ground vehicle, you coast quietly to the side of the road. Airplane engines have to be extremely reliable, because when they quit, you are much worse off. Reliability is achieved through careful attentioon to detail and using processes and parts with long track records.
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  #30  
Old 10-27-2015, 08:47 PM
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Another thing no one has mentioned is, pay attention to tolerances.
An air cooled engine that is subjected to a wide range of temperatures is built to somewhat looser tolerances than a liquid cooled engine where the temps are quite controlled.
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