Are narrow and wide deck O-320's the same size?

FORANE

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FORANE
Looking at putting a new engine on my Lancair. Cowl is tight, very tight. It has a narrow deck O-320. Is the wide deck O-320 physically wider than the narrow deck motor?
 
Looking at putting a new engine on my Lancair. Cowl is tight, very tight. It has a narrow deck O-320. Is the wide deck O-320 physically wider than the narrow deck motor?

"Lycoming's first (of the post-war era) cylinder design was what came to be known as narrow-deck engines (Lycoming refers to them as Standard cylinder flange engines). The flange area of the cylinders was thin, and required the use of hold down plates. These plates fit on top of the flange, under the nuts. The nuts were an internal wrenching design, with provisions for safety wire. In an (apparent) effort to eliminate these plates, Lycoming re-designed the flanges to be thicker, and used an ordinary (in appearance) flat nut, with no need for the safety wire (what is known as wide deck). It is noted that the crankcases vary slightly between the narrow and wides, Lycoming SI 1345 discusses what crankcases to use as replacements, as required."

Check out this link - https://generalaviationnews.com/2009/10/07/ask-paul-wide-deck-vs-narrow-deck-engines/

google is your friend.... ;)



 
I doubt that article, although it may be true. The case is the same, and the stroke of the cylinder hasn’t been increased, so I’m unconvinced that a wide deck would be “wider”. The flange being thicker, doesn’t mean the cylinder is longer.
 
Found that link already, read it, still don't know the answer to the question if a wide deck o-320 requires more horizontal space than a narrow deck inside the cowling.

Current motor is a o-320, the original o-320 before they started adding sub-designations to the o-320 nomenclature (a narrow deck). It has 10:1 pistons in it. I had to bump out the lower cowl in a few locations (such as lateral to the left front rocker cover) for clearance because it was rubbing.
 
Is the wide deck O-320 physically wider than the narrow deck motor?
FYI: this is dated info, but if I recall, the horizontal dimensions between a WD and ND are the same. But due to the cylinder differences the baffling will need to be altered and there can be other external differences with the mounts, etc. depending on specific model number comparisons. A call to Lycoming support with the P/Ns and S/Ns of the engines you wish to swap should answer your question specific to your aircraft.
 
What Bell206 said. I recall WD and ND 320s being the same width, parallel valve 360s are an inch wider, and angle valve 360s another inch wider. I have a no suffix 0-320 ND and some WD cylinders in storage. I can compare cyl height on Monday if that helps.
 
Thanks for the replies. My local mechanic thought they were the same width as well. I have read the narrow decks may be 10-15 lbs lighter though, unconfirmed. My plane tends to be nose heavy so less weight on the nose would be welcomed.
Need to find a motor now.
 
Thanks for the replies. My local mechanic thought they were the same width as well. I have read the narrow decks may be 10-15 lbs lighter though, unconfirmed. My plane tends to be nose heavy so less weight on the nose would be welcomed.
Need to find a motor now.

Replace prop with newer lighter composite prop.
 
I don’t know Lancairs, but if battery is in the engine compartment, maybe you could move it into the tail?
Battery was already in the empennage. I added a second battery in the empennage to help. The larger mkII tail on later models helped this some I hear.
 
see if this anything

i am noticing I can dl such files to my laptop but not on my ipad. This is a pdf of engine dimensions, lmk if you cannot see it.
ahh, couldn't see it on phone but can on laptop.
good info, thanks.
 
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