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 aneroid carb recipe 
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Joined: Tue May 06, 2014 5:34 pm
Posts: 42
Doing some work on a 7045228 carb, first time working on such a unit. It has what I believe is an altitude compensator with some sort of a jet at the bottom where the "shooter glass" usually is on later APT carbs. This one does not have APT, either the early or late style one.

It also does not have the extra power piston/metering rod.

Could I just block that small "jet" with a 6/32 setscrew and treat this build just as any other early non apt carb ? Looks to me like the logic way of doing this, or am I missing something ?

I know those are not the most desireable units, just trying to help a friend with what he has.

Frank.


Sat Nov 12, 2016 9:54 am
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Joined: Sat Jun 21, 2014 5:38 pm
Posts: 17
I have run into that on some 75 and newer Cadillac Q-jets, but not on any 75-76 Chevy 350-400 carbs? I have even owned 73-77 Chevelles and Montes with Q-jets and I know I rebuilt them and don't remember seeing this in any of those carbs. Of course this is going on some 20 plus years ago since I owned them. Anyway on the Cadillac I just removed it and I believe just plugged the holes and used the plastic filler piece and never had a problem.


Sat Nov 12, 2016 1:48 pm
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Joined: Fri Feb 08, 2013 2:37 pm
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Does it actually have the accordion pleated aneroid or is it just a threaded solid piece with a tapered metering rod? I've seen several of the simple solid APT deals and just a couple months ago found an aneroid in a Cadillac carb, first I have seen outside of Roe's book. It is just an adjustable main jet so you can use it or plug it, as you see fit.


Sun Nov 13, 2016 8:12 pm
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Joined: Tue May 06, 2014 5:34 pm
Posts: 42
It's just a threaded solid piece with a tapered metering rod. Guess I'll just plug the jet at the bottom and threat that build just like a regular non apt carb. Thanks,

Frank.


Mon Nov 14, 2016 7:18 am
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Joined: Fri Feb 08, 2013 2:37 pm
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I erroneously called it an APT in the post above, when it is actually an AMJ ~ Adjustable Main Jet, because it affects both part and full throttle. Such a thing can be handy in a street carb if you are in a place where the E-10 is occasionally E-15. The last one of these I worked with was on a 400 Pontiac in a Firebird, a real nice car. The gentleman has an Innovate MTX-L we used to tune the thing and that AMJ was a handy tool to easily fiddle with the lean limit for cruising.


Mon Nov 14, 2016 12:49 pm
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Joined: Tue May 06, 2014 5:34 pm
Posts: 42
I'm wondering what activates it, like what makes it go up or down in that jet ?


Mon Nov 14, 2016 1:45 pm
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Joined: Fri Feb 08, 2013 2:37 pm
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I have only seen ones that have a threaded adjustment. Did you notice an E-clip below the screw slot and above the threads? Remove the brass cup pressed into the lid so you can have access when the carb is assembled. A rubber vacuum cap in the hole keeps the dirt out.


Mon Nov 14, 2016 3:16 pm
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Joined: Sat Aug 24, 2013 7:57 pm
Posts: 152
Location: Frostburg, MD
I had a 70xxxxx '75 Cadillac carb with aneroid. I recently obtained another '75 caddy carb, but I haven't looked at it closely.

Really, are they any advantage over the normal carbs?



Fwiw, I have several '76 Cadillac carbs, all are "normal" 170xxxxx carbs, although there are two versions with the same #. Subtle differences.


Sun Nov 20, 2016 11:44 am
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Joined: Tue May 06, 2014 5:34 pm
Posts: 42
dave brode wrote:
I had a 70xxxxx '75 Cadillac carb with aneroid. I recently obtained another '75 caddy carb, but I haven't looked at it closely.

Really, are they any advantage over the normal carbs?


I don't believe they are an advantage. I think they mean more work and headaches...


Sun Nov 20, 2016 6:36 pm
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