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  #46 (permalink)  
Old 09-19-2006, 10:56 PM
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Glad to here the problem was solved, but I am guessing that the epoxying the plugs didn't solve it. The plugs should basically only give you a massively rich condition at idle. Quadrajets can be so wierd. I was chasing a bog off idle and went through it without really finding anything strange. Back on the car for a test drive and I almost ate the steering wheel at 4500 RPM, with it catching and pulling me back in the seat at 4300 and off again at 4500. That high RPM drop off wasn't there before. I haven't had the chance to go back through it, but I'm betting more on the top bowl gasket not positioned exactly, allowing a large enough air leak to prevent the secondaries from sucking fuel properly. You might have just positioned the gasket better and solved the problem on the last assembly.
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  #47 (permalink)  
Old 09-20-2006, 08:56 AM
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One of the plugs could have been leaking but instead of dripping, sucking air. Who knows. I spent the better part of an hour just figuring which part of the secondary went where. Same with the idle circuit, but I didn't have a problem with that, I just figured if I was going to do it, I had better do it right. I'm back to where it was before now. Also, I had noticed my consistency was slowly disapperaing at the track, I wonder if this was something that had been there a while but had just gotten bad enough to finally seriously hinder performance. I still think I need to loosen the secondary air doors just a little though... Things to do, but not enough track time.
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  #48 (permalink)  
Old 09-20-2006, 09:20 AM
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Did you remove the choke lockout mechanism? Murphy's law will apply here.
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Old 09-20-2006, 09:30 AM
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The choke is still in place. It sees a lot of street time, and very occassionally, someone else drives the car. It has to have some semblance of street manners.
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Old 09-20-2006, 09:44 AM
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I'm not talking about the choke, just the choke lockout mechanism. It prevents the secondaries from opening if the choke is applied, and can hold the secondaries out even when the choke is open if it is misadjusted. You wouildn't want this to come into effect at the strip as it will make a huge difference in the carb. Are you familiar with the choke lockout mechanism on your carb?
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  #51 (permalink)  
Old 09-20-2006, 05:29 PM
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The lockout is actuated by more than just it's weight alone. When the choke is off and the lockout is disengaged There is a pin on one of the other choke arms that pushes the top of the weight back swinging the bottom foreward. There is no way that that lockout can be engaged if the choke is off. Plus it does not have enough ckoke to be on more than about 2 1/2 minutes before the lockout comes off. The lockout arm also acts as a spacer and I'm not about to hack my linkages up.
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  #52 (permalink)  
Old 09-21-2006, 10:47 AM
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You don't have to hack up your carb to defeat the lockout. Unless Edelbrock significantly changed the choke mechanism, the lockout lever is on a stub all by itself, captive between the vacuum break mechanism baseplate and the body. Removing this lever involves no hacking and assures that the secondaries will open whenever you want them open.

I have 2 Q-jets I use on my engine, one is a stock 7040207 Q-jet off of a 1970 350 Chevy that gets me 18-20 mpg, the other is an 800 cfm unit off a 425" Caddy and is heavily modified. When I go to the strip, I take the driver carb off and put the monster carb on, takes all of 5 minutes.
The 800 cfm unit cost me $8 at a boneyard, and $10 for a rebuild kit. I have removed all the choke horn, the primary metering rods are gone for area equivalent jets, the linkage is 1:1 on the secondaries, notched the air valves, drilled out all the passages per Doug Roe, etc. Throttle response is awesome, and it set me back less than $20, maybe $30 if you count the chemicals.
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  #53 (permalink)  
Old 09-21-2006, 11:03 AM
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Check to see if your secondaries are opening fully. If they are, that may be your problem. The secondary butterfies are designed to work with that flat plate in the secondary holes. If the butterflies are vertical, the F/A ratio is compromised. The secondary butterflies should NOT quite open up to the vertical position.

tom
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