#17057232 '77 Caddy

[rich ullsmith]

This is interesting.  In the cavity where a plastic cup usually resides (think 75-76 APT models), there is a copper bellows???( I'm guessing,) with a metering rod on the bottom that goes into a jet. Also, next to a primary jet there is another jet. What is their purpose? This carb is going on a 2000 Vortec 350. Nothing special, just a 5000lb. truck.   2.73
rear, 4900 lbs., old man driving. Anyone guess what the MPG potential is?   

[Ethan1]

This is interesting.  In the cavity where a plastic cup usually resides (think 75-76 APT models), there is a copper bellows???( I'm guessing,) with a metering rod on the bottom that goes into a jet. Also, next to a primary jet there is another jet. What is their purpose? This carb is going on a 2000 Vortec 350. Nothing special, just a 5000lb. truck.   2.73
rear, 4900 lbs., old man driving. Anyone guess what the MPG potential is?   

 Have a photo?

[rich ullsmith]

I'd love to, but the site says the file is too large. 1 pic.  Any ideas?

[Ethan1]

I'd love to, but the site says the file is too large. 1 pic.  Any ideas?

 Can you send me an e-mail of the photo? I will resize it for you.

 etrowb@msn.com

[Ethan1]

 Here you go:

 

[Ethan1]

 This part is the Aneroid Metering Rod Assembly. Cliff will know exactly what it does. Might try a search as well.

[rich ullsmith]

Thank you Ethan.    Looks like this aneroid thingy is meant to limit the accel. pump shot on a warm engine. Sounds reasonable.

[Cliff Ruggles]

That particular part is designed for high altitude applications, and will vary the depth of the metering rod in the jet with changes in altitude.  Those are pretty rare parts, and I've never spent much time with them, as I'm not overly fond of the 1975 and early 1976 carburetors that used that APT system.  The later style is just a lot better deal all the way around.....Cliff