Short vs Long Tower

[andoman]

Referring to the oil pressure relief adjustment tower.
I’ve read there are short and long versions and that 3 or 7 adjustment washers can be used depending on length. A search of the parts manual has not answered my question. I only see the standard and externally adjustable versions.
Is it simply that the externally adjustable unit is the “long” version?
And where does the 3 or 7 washer limit come from? The Parts manual calls for washers “as needed.”
Thanks.

 

[jrs14855]

This is not from the parts catalog but an internet search.
Long Lyc pn 76159
Short 61143
Long would be 7 washers short appears not to have enough room for seven washers.
I have also seen the long referred to as Wide Deck(wide cylinder flange engine)
IIRC Mahlon describes the short as looking like a top hat.
I have the long, non adjustable on a wide deck 0 320
The parts catalog I have is for wide deck engines, The short would probably be in the narrow deck catalog.

 

[jrs14855]

Current Lycoming pn for plug oil relief valve is 76529. For all wide deck 0 320. 0 360 would be the same.

 

[jrs14855]

Read Lycoming Service instruction SI1172C

 

[andoman]

Exactly the info I was looking for.
Thanks!!!