bl75vette

Took the car for a trip to Englishtown for the Spring swap meet. On the Parkway I punched the pedal and the secondaries were not kicking in. Can anyone suggest what I look for or try to correct the problem. I was reading about the lockout pin adjustment, but I am not sure if this could be one of the problems.

MotorHead

Your gonna have to give us more info. If it is a Holley with vacuum seconadary then make sure the linkage etc. is not binding on anything. It could also be a ripped diaphram inside the vacuum unit. To test for this take it off and there is a hole that goes to the carb, grab the linkage where it opens the secondaries
and push up on the diaphram and them put your finger on the hole. The diaphram should stay up in the same position if it slowly goes down it ripped.


[Modified by MotorHead, 4:54 PM 4/28/2002]

bigvette1

Read the post and can't tell what carb you have. Tell us and then people can help?

bl75vette

Sorry guys, forgot to mention that the carb is a 75 Rochester Quadrajet. :conehead :conehead

razz1980

mine were kinda sticking when i got my vette..i would use a big dose of carb cleaner in case it is just gummed-up..it wouldnt hurt to try and how knows it worked for me ;)

bigvette1

Take off the air cleaner so you can see the carb. With engine off, manually open and close the secondaries top air plates. Make sure the plates and the secondary rod hange in the center of the plates moves freely. You may have to release the lockout pin that is on the lower side behind the choke. There is a pawl that holds the secondary closed when on choke. Just release the choke from fast idle and push the pawl clear of the pin.

See if the seondaries open and close freely on the top of the carb. If not clean the mechanism up with carb cleaner on the externals. Hold the top plates open and open the accelerator max. and see if the lower secondary throttle plates open and close. If not checkout the linkage rods. These secondaries are mechanical and they either open or not when you floor it and the air flow calls for them. Let us know.

theandies

Read Lars's paper in tech tips on Q-jet tuning that will get you going.
John

stickboy

take the air cleaner off and warm the engine up, check to make sure the choke opens the whole way, and if the choke is open the whole way make sure the lock out is off the pin. My lock out got jammed up on the pin one time so it never unlocked. :confused:

vetterATL

Make sure you are getting full throttle. I had this problem and thought for sure I was getting full throttle, even after I checked it twice. Have a friend push the gas to the floor (motor not running) and see it you can push it open any farther (give it a good push). Its like night and day when those big azz secondaries open up!!!! Good luck!

Corellian Corvette

Had the same problem. Over the years someone bubba'd the linkage so putting the pedal to the floor wouldn't open the secondaries.

Good advice above. Get a friend to hold the pedal down and see if they open. Remember -- there is a pin on the passenger side that you will have to move out of the way.

Rockn-Roll

If you have the original Q-jet like I do then it's probably the linkage on the drivers side. There's a spring in the secondary shaft which is what actually opens the secondaries. The problem I found with mine was that the spring also causes the secondary throttle plates to bind against the wall of the venturi and it gets stuck. The Q-Jet has a built-in fix for it...the linkage which connects the primary shaft with the secondary shaft has a long lever extending up along the carb body. This lever should contact a tang which sticks up from the secondary shaft and gives it the needed leverage to nudge the throttle plates open...then the spring does the rest. Mine just needed some needle nose pliers to adjust the lever so that it contacts the tang sooner.

Also, the adjustment for this IS included in the repair manuals, however, their approach involves measurements that don't get the lever touching the tang properly IMHO.

And, the lockout on the passenger side should be releasing when your choke opens all the way up. Personally, I removed my secondary lockout...It's just there to prevent poor fuel economy, cause if you open up the secondaries before engine reaches operating temperature then the air/fuel mixture will be slightly off...a bit lean I believe, which could result in excess NOX and higher combustion temperatures. In otherwords if I want to warm my engine up I do about a 5 second WOT like from 40 to 80. It's more fun that just sitting in the garage and waiting until the thermostat opens.