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HalfMoon |
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Senior Member ![]() ![]() ![]() Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region ![]() |
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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Olympic 914 |
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#2
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![]() ![]() ![]() Group: Members Posts: 1,742 Joined: 7-July 11 From: Pittsburgh PA Member No.: 13,287 Region Association: North East States ![]() ![]() |
This was MANY years ago but I had a Carter Thermo-Quad on my Olds 442 and I seem to remember that you could adjust the top secondary plate opening with a screw that tightened a spring and there was a lock screw that held it in place. I think they were mainly vacuum controlled though.
BICBW |
Maltese Falcon |
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#3
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914 Guru ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 5,068 Joined: 14-September 04 From: Mulholland SoCal Member No.: 2,755 Region Association: None ![]() ![]() |
This was MANY years ago but I had a Carter Thermo-Quad on my Olds 442 and I seem to remember that you could adjust the top secondary plate opening with a screw that tightened a spring and there was a lock screw that held it in place. I think they were mainly vacuum controlled though. BICBW Thermo quad was basically like a QJ with the spread bore style . The innovation was in the center section (which holds the fuel bowl chamber), it was made from black phenolic resin. Principal was to isolate heat from the intake manifold , creeping upwards towards to the carb...causing vapor lock. I simply ran a cool - can stuffed with ice and the Quadrajet ran all sessions without a hiccup. Phenolic resin spacer blocks are used as intake insulator spacers on 930 hot rods, and all sorts of other forced induction engines. Thermo quads were factory equipment on many Mopar Darts, Dusters+ Roadrunners in the day. Half Moon...good diagnosing ! Marty |
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