I've suspecting my carb is to blame for my horrible track times after mods. But I'm not too sure what to be looking for.

With the motor off if I pull the throttle to WOT I don't see anything move, I didn't check for the butterflys below the choke, cause the choke was blocking my view, should I check for that?

What about the 2ndaries, I didn't see those move, but wouldn't the motor have to be running to tell?

it's a vac. 2ndary carb.

also, I saw a lever that works with the throttle towards the back, and it didn't move when I pulled the throttle, only if I moved it by hand.

 

I just rechecked to make sure, that back lever does move when I pull back the throttle but not right away, and I can still move it more when at WOT.

 

I don't have one of those carbs, and haven't been around them enough for any hands-on experience. But, a quick trip to www.edelbrock.com yields the following information:
"The Secondary Throttles (1) begin to open when the Primaries are about 65% open. The Primary and Secondary Throttles arrive at the WOT stop at the same time.

"Air flow through the Secondary side is controlled by Air Valves (2). These valves are located in the secondary bores above the throttle blades. They are balanced against a counter weight and open to admit additional air flow only if there is enough air velocity to allow the proper operation of the Secondary Metering Systems."

From this, I would say that when operating the throttle arm (attached to your throttle cable), you shouldn't see any secondary throttle movement until well past 1/2 way open, and then the secondaries should start opening and be full open at the same time as the primaries. But, looking down into the carb, you won't see that because of the air valves in the secondaries that only open with flow (unless you push them open and look through while doing this).

I also don't know about any choke secondary lock-out, but if it exists, you need to open the choke fully before you attempt to check any of this.

FWIW, this isn't a vacuum secondary carb, in the traditional defination. VS has a vacuum diaphragm that actuates the secondary throttle blades. This system (like the q-jet) uses the air valve to perform the airflow limiting function as provided by a VS carb. Holley and Demon are the only ones I know of who make true VS carbs (there may be others).

 

ummmm how did you get vac secondaries on an edelbrock????? every last one i have seen was mechanical.

 

Mark,
I have a 600 performer series carb. Unfortunately I haven't had it long enough to help you out. My friend had one also and did say that there is a secondary blockoff if the car is not warmed up yet.

The secondaries or counterweight won't move with the car off. You need to have the car warmed up and running to see any movement of the secondaries. You probably won't see the counterweights move just sitting still because no airflow. You can hold open the counterweight valves and blip the throttle to WOT and you should be able to see the secondaries open.

I think this carb is too small for my engine and am going to try and put on a borrowed 750 edelbrock and see how it does. With the 600 I cannot get the car to run rich.

I'm also seriously considering a Holley dp if these edelbrocks don't work out.

Craig

 

I have an Edelbrock 650 on my 350. Mark, you saw my other post in the general tech board, i was running 15.5. Today, i got pissed off because i lost to a stock 4x4 truck last night, so i went out and started dinkin with the carb because of a lack of get-up and go. I noticed that the top flap on the secondaries (back) is opened by vacuum (weighted flaps) and the bottom flap is mechanical. Started the car up, revved it a few times, things didn't budge. Stuck my finger in the hole to open up both flanges, revved it, shot to about 6500 before i knew what happened. Never did that before, so i assumed that the secondaries weren't opening. So i took it to a friend and pointed the forementioned info out and he dinked around with it and noticed that unless the primary choke flap thing is COMPLETELY open, the secondaries can't open at all. I have an electric choke and the servo deal wouldn't let the primary choke flap open all the way. So we loosened the servo and turned it about 1/5 of a turn counter clockwise so the flap stayed open all the time. Took it out for a spin, i chirp the tires from start, 1-2 shift, 2-3 shift. In four telephone pole lengths I'm at about 105 (thats near 1/4 mile), my stock mech speedo doesn't keep up it lunges to 25, stops, lunges to 60, stops, lunges to 70 and then starts climbing like normal until it bounces off the bottom of the gauge cluster. I'm expecting to run 13.1 at the track. I hope this is your prob and I hope it helps, cuz it feels great going that fast after all the work we've done.