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  #1  
Old 04-11-2021, 09:45 PM
00Dan 00Dan is online now
 
Join Date: Nov 2016
Location: Atlanta
Posts: 130
Default Lycoming SB258 Sump Riser

Does anyone have some pictures they could share of the sump riser for very early O-320s that have a 10-3678-32 carburetor installed? This part is detailed in Lycoming SB258 for 50s era Pipers.

I found some threads here from several years ago but unfortunately the picture links no longer work.
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  #2  
Old 04-12-2021, 08:28 AM
lr172 lr172 is online now
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by 00Dan View Post
Does anyone have some pictures they could share of the sump riser for very early O-320s that have a 10-3678-32 carburetor installed? This part is detailed in Lycoming SB258 for 50s era Pipers.

I found some threads here from several years ago but unfortunately the picture links no longer work.
Pretty sure there are two versions of the sump with different ID's. the -12 and -32 carbs had different throat size and different sumps to match with them.

Larry
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  #3  
Old 04-12-2021, 11:21 AM
theduff theduff is offline
 
Join Date: Jan 2012
Location: Fallbrook Calif.
Posts: 333
Default SB 258

Send me your email address and Iíll send you a bad copy of a 1959 Service Bulletin !
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  #4  
Old 04-12-2021, 11:23 AM
00Dan 00Dan is online now
 
Join Date: Nov 2016
Location: Atlanta
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Originally Posted by theduff View Post
Send me your email address and I’ll send you a bad copy of a 1959 Service Bulletin !
I found a good copy on the Piper forums! At this point I’m trying to see if the part can even be sourced or if it must be fabricated.

Did you perform the mod and did it help?
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  #5  
Old 04-12-2021, 11:29 AM
theduff theduff is offline
 
Join Date: Jan 2012
Location: Fallbrook Calif.
Posts: 333
Default Sump Insert

We made our own per the dimensions from the SB. The project that I built the engine for has languished and hasnít flown yet. I know from dyno testing at a friends shop that it does work and they are experimenting with their own inserts to improve the fuel distribution on those early sumps.
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  #6  
Old 04-12-2021, 01:21 PM
00Dan 00Dan is online now
 
Join Date: Nov 2016
Location: Atlanta
Posts: 130
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Quote:
Originally Posted by theduff View Post
We made our own per the dimensions from the SB. The project that I built the engine for has languished and hasnít flown yet. I know from dyno testing at a friends shop that it does work and they are experimenting with their own inserts to improve the fuel distribution on those early sumps.
Did you get any quantitative data from the dyno test?
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  #7  
Old 04-12-2021, 01:48 PM
theduff theduff is offline
 
Join Date: Jan 2012
Location: Fallbrook Calif.
Posts: 333
Default Dyno Data

I was just a spectator not a participant, so no documentation. I believe your sump is the one with unequal length tubes and the Carb located aft on the sump instead of in the center ? The early 320ís used this sump and the Pipers in the certified world (Cubs) are stuck with it thus the inserts to deal with the roughness and unequal flow distribution. They make a special part # carb for the Carbon Cub to improve this problem, and I happen to have one that was going to go on a TriPacer. Another option is to upgrade to the latter sump which I have several.
Trust me your not the first to pull your hair out trying to get good numbers with this set up. Email me at : theduff at EarthLink dot net with a phone number if you want some help.

Duff
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