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> OT-Quadrajet 4MV question, My darkside teener carb prob
HalfMoon
post Sep 13 2014, 06:11 PM
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Hi all,
While this is slightly off topic it IS at least in reference to a teener, specifically my v-8 converted teener.
It's a 350 sb and it uses a 1970 Qaudrajet 4MV carb. I know alot of folks don't like these but when they're dialed in right they give a good blend of economy and performance.

My question is twofold-
1. No doubt you're familiar with the secondaries "air flaps" that are visible on the top of the carb but down deep are the secondary "baffles". You can manually open them up all the way wide but on the car the linkage only open them a crack. I imagine further opening is a function of engine air flow and demand. Or am I totally wrong and they are in fact supposed to open wide via linkage?
2. Has anyone ever experienced constant vacum at the port feeding the secondary dash pot? It's the one that's connected to the secondary air flaps on top. It's supposed to stop it's vacum when you get out of the primaries and get into the secondaries thus allowing the air flaps (the ones on top that you can see) to open. For some reason mine has constant vacum and as a result I can't get my secondary air flaps to open (so I've had to disable that dashpot and cap the vacum port).
That dashpot is supposed to prevent the air flaps from "bouncing open" and I assume I'm gonna get a bog when I do quick shifts if I don't resolve this problem :-(

Your experience is appreciated.
David
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messix
post Sep 14 2014, 12:13 AM
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when the throttle is all the way open the secondary throttle plates [the lower plates] do not open all the way?

are the primary [small diameter] open all the way
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HalfMoon
post Sep 14 2014, 09:09 AM
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QUOTE(messix @ Sep 14 2014, 02:13 AM) *

when the throttle is all the way open the secondary throttle plates [the lower plates] do not open all the way?

are the primary [small diameter] open all the way


Correct! The primaries open all the way but the secondary baffles do NOT open all the way and the secondary baffle choke/stop preventer has been removed.
TY
David
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messix
post Sep 14 2014, 12:55 PM
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QUOTE(HalfMoon @ Sep 14 2014, 08:09 AM) *

QUOTE(messix @ Sep 14 2014, 02:13 AM) *

when the throttle is all the way open the secondary throttle plates [the lower plates] do not open all the way?

are the primary [small diameter] open all the way


Correct! The primaries open all the way but the secondary baffles do NOT open all the way and the secondary baffle choke/stop preventer has been removed.
TY
David

"baffels"?

there are secondary throttle shaft and plates, and there are secondary air valve, if you are talking about the flow directors that are between the two they do not move.

the air valve will not open all the way when the engine is running until the vacuum signal drops on the primary side and the vacuum servo allows it to move. also the secondarys will not open while the choke is in operation.
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HalfMoon
post Sep 14 2014, 09:51 PM
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QUOTE(messix @ Sep 14 2014, 02:55 PM) *

QUOTE(HalfMoon @ Sep 14 2014, 08:09 AM) *

QUOTE(messix @ Sep 14 2014, 02:13 AM) *

when the throttle is all the way open the secondary throttle plates [the lower plates] do not open all the way?

are the primary [small diameter] open all the way


Correct! The primaries open all the way but the secondary baffles do NOT open all the way and the secondary baffle choke/stop preventer has been removed.
TY
David

"baffels"?

there are secondary throttle shaft and plates, and there are secondary air valve, if you are talking about the flow directors that are between the two they do not move.

the air valve will not open all the way when the engine is running until the vacuum signal drops on the primary side and the vacuum servo allows it to move. also the secondarys will not open while the choke is in operation.


As previously stated:
"Baffles" (and that's what the diagram refers to them as) whch is to say the lower flaps in the base of the carb have had the choke/preventer pin removed (ages ago) so that's not holding them back.
The servo you are referring to for the upper "air flaps" is holding them closed (when hooked up) no matter how long you allow for warm up nor within any throttle position after warm up (which means the port from which a vacum source is powering that servo is not un vaccuming in any range or basically locked when attached to the correct vacum line) I have disabled it and the servo unloads allowing the air flaps to open. But that said, a bog is surely to occur as the air flaps will bounce during shifts.
Attached Image Scondary air "baffles"
Attached Image Secondary "air flaps"
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Posts in this topic
HalfMoon   OT-Quadrajet 4MV question   Sep 13 2014, 06:11 PM
ClayPerrine   The air flaps on the top of the secondaries move t...   Sep 13 2014, 09:31 PM
HalfMoon   The air flaps on the top of the secondaries move ...   Sep 13 2014, 10:04 PM
messix   when the throttle is all the way open the secondar...   Sep 14 2014, 12:13 AM
HalfMoon   when the throttle is all the way open the seconda...   Sep 14 2014, 09:09 AM
messix   when the throttle is all the way open the second...   Sep 14 2014, 12:55 PM
HalfMoon   [quote name='HalfMoon' post='2085929' date='Sep 1...   Sep 14 2014, 09:51 PM
messix   [quote name='messix' post='2085995' date='Sep 14 ...   Sep 14 2014, 10:00 PM
messix   this might help https://www.youtube.com/watch?v=Wf...   Sep 14 2014, 12:32 AM
HalfMoon   this might help https://www.youtube.com/watch?v=W...   Sep 14 2014, 09:10 AM
Olympic 1.7   This was MANY years ago but I had a Carter Thermo-...   Sep 14 2014, 10:04 AM
HalfMoon   This was MANY years ago but I had a Carter Thermo...   Sep 14 2014, 09:37 PM
Maltese Falcon   This was MANY years ago but I had a Carter Thermo...   Sep 16 2014, 09:22 AM
Mike Bellis   How have you verified this problem? Vacuum is not...   Sep 14 2014, 10:23 AM
HalfMoon   How have you verified this problem? Vacuum is no...   Sep 14 2014, 09:40 PM
messix   on second thought.... have you checked to see if ...   Sep 14 2014, 12:59 PM
HalfMoon   Here is the throttle linkage that controls the pri...   Sep 14 2014, 09:58 PM
HalfMoon   And here is the dashpot that does not release (whe...   Sep 14 2014, 10:01 PM
Maltese Falcon   You are using a spread bore QJ manifold, right? Th...   Sep 14 2014, 11:58 PM
HalfMoon   This was the problem. The spring that creates tens...   Sep 15 2014, 09:24 PM
HalfMoon   :Qarl:   Sep 16 2014, 09:54 AM
messix   now get those plugs epoxied up! :shades2:   Sep 16 2014, 04:51 PM
Dr Evil   I bet it is the spring that creates tension on the...   Sep 16 2014, 05:24 PM
HalfMoon   I bet it is the spring that creates tension on th...   Sep 16 2014, 06:37 PM


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