Last night I had my brother over to look at the car. Issue is it just seems way underpowered to me.

I had him take it for a test drive and he immediately said something is wrong, so we took it back to the house and looked at the carb.

Carb is the quadrajet, id number is 7028276.

Basically while in park, he was accelerating and watching what was happening. From my observations and his comments, it would appear that when he gets on it, the secondaries are not opening as he would have expected them to.

My question is - is there something that I should look for? Or should I look at replacing it?

Whomever restored the car has gone out of his way to keep it a stock looking car, so I want to stick with the quadrajet.

Apologies if the information is too vague, he's the mechanical one, not me.

1st thing I would do is check for full throttle travel. Don't know if yours is cable or linkage (You did not state the vehicle year), but both are adjustable.

With the engine off, disconnect the cable/linkage at the carb. Then pull back the throttle linkage on the carb and and see if it is traveling rearwards enough to open the secondaries. Fiddle with the cable/linkage length and see if it gets you the travel you need.

Apologies - car is a 1968 Firebird. It has a 400 dropped in from a 69 GTO.

I'll try later and see...

So you should have a cable. Make sure you re-read what I put above as I edited it.

Appreciate the response, will peak at it tonight and see if I can make sense of it all. If not, I'll have my brother come look at it.

Without seeing it, I'm trying to visualize... Let's say it's not opening them, is the adjustment of this cable obvious?

Sounds like the linkage for the secondaries is not adjusted correctly. I had this problem and was able to solve it via Cliff Ruggles book, an invaluable resource to have. You need to bend the secondary linkage adjustment at the primaries. Some Q-jets were limited in secondary travel(what you are looking for is full 90 degrees)for emissions purposes.

There is an adjustment for the tension of the secondaries. It's on the passenger side on the secondary shaft. There is an allen head set screw that keeps the tensioning screw set. To set it correctly,
loosen the allen head screw and take all tension off. Turn the set screw until tension just starts on the flaps, then turn 1/2 to 5/8 and tighten everything up. It shouldnt take much for the flaps to open up.

Correct, but that just deterimines how fast the air flaps open up but won't affect the total travel of the secondaries.

I thought that was what he was asking about...? He mentioned the flaps didnt open as expected when they got on it (top of carb). It doesnt sound like he's checked the travel of the throttle plates(butterflies on the bottom)yet. You're right though, if the throttle plates arent opening all the way it wont create enough vacuum for the secondary flaps to open.

The secondary air valve will not fully open unless the engine is "under load". Revving it in neutral cannot simulate reality.

The Firebird carbs, usually on the higher HP engines, had a "limiter" on the secondary. Some of you Firebird guys know more about that than I. GTO carbs did not have them.

I believe, 7028276 is a "Ram Air" carb for a '68 GTO with auto trans. MAYBE the manual, I forget... Cliff CAN tell you for sure! But it's definitely '68.

Jim

Car is an automatic with Ram Air. When we were looking at it last night, she was in park. Concern is that they were not opening up at all, even a little bit. Would you not have expected them to open even a bit?

Don't concern yourself with the air valve right now. Move the linkage by hand to WOT and push down the air valve butterfly on the top of the carb. Look down the throat, are you secondaries at 90 degrees(straight up and down)? Like Mr. P-body said, reving the engine in neutral won't necessarily open up the air valves. To delve into the next level of "a lack of power" issue, check your base timing and total advance as well and report back.

The problem with trying to open them up in the driveway is the dashpot is set to open the air valves at a certain rate. It's pretty scary holding the throttle down for long enough to open them up standing next to the engine bay. Especially if you're looking down the throat.
Something you might look at is there is a latch on top of the carb that holds the secondary air flaps from opening while the choke is on. It's there to keep the revs down until it's completely warmed up. Occasionally it gets worn and won't release the flaps at all. Not even after the choke is off. Try opening it with your finger to make sure it's free to open.

I wanted to thank everyone for all of their help. Finally got around to looking at it and to temporarily solve the problem we removed this piece which was connecting the secondaries and this white round thingy (Sorry - like I said, I am not very knowledgeable at this point) Seems to have solved the problem.

I also ordered the book that was suggested. I'm starting to read through it now(hopefully next time I will not reply with " white round thingy ").

I'm a computer guy, so still trying to learn all of this car stuff!

At any rate, we noticed that my car seems to be missing the kick down switch. I have been poking around the web looking for pictures as I can't seem to find the bracket that the switch would connect to on Jegs or Summit's web sites. I'm still researching this, but if anyone has any pictures, part numbers, or anything like that readily available, please let me know.

Once again - thank you all for the quick responses. Sorry for this delay - just got around to getting my brother over here to help me again.

Ames sells the kickdown switch bracket, part# FN460 - $20. The switch itself is not reproduced, hard to find and expensive if you do.

Oh great! Thanks for that!

Is this not the switch?

http://www.jegs.com/i/B-M/130/20297/10002/-1?parentProductId=748054

That's an aftermarket switch and works just ok.
Here is what originals look like

Would you recommend holding out to find an original?

When you mentioned that the other one works just ok, have others had issues with it? Is there something that I should look out for?

The problem with original kickdown switches is that they are electrical devices that are 45 years or so old and lived through countless cycles of extreme hot and then cool down under the hood. Whey you see one on E-pay, you have no idea what lies under the cracked rubber boot and the plunger.

I went with a Lokar system.

Would this be the kit you used?

http://www.jegs.com/i/Lokar/625/KD-2400HTK/10002/-1?parentProductId=749858

Yep. I had some install issues that you may want to read about in "Buyer Beware"

I have an original one I may be talked into selling. When I needed one, I looked for months and months. Then after finally finding one, I found another the next day, so I picked it up too.

PM if interested. It looks just like what Doug posted.

I'd take 68tpls400 up on his offer. The originals install and work good. They also look good if trying to keep everything original.

Since this thread is about secondaries...

How do you adjust the delay in the opening of the rear butterflies? I believe that is my lagging issue with bogging at acceleration. The butterflies open slightly upon WOT before the RPM's build. This causes a bog. If I hold them closed, no initial bog.

Is that what colorado's above post is referencing?

Edit: I do not see any allen screw adjustment on the passenger side.

If you want to "see" it, you have to look up from below.



Your linkage may vary.

OK, found it. Thanks.

I did adjust it to add some tension. Unfortunately, I did not have a screwdriver on it when I loosened the allen screw, so it spun back and I do not have a reference point to start from. Seems to not be bogging nearly as bad from a dead stop. I may add a little more Thursday night and try again. Still bogs when moving and going to WOT. Might be a timing advance issue. I will have to read up a little bit on the Pertronix III to see what is up with that.

With the spring loose, turn the screw just till it starts to close the flaps, from there turn an additional 5/8 of a turn and tighten up. That will be a good starting point.

I did that per your earlier post. It was bogging a lot, so I gave it another 3/8 and the bog has been reduced considerably. I will give it another quarter turn when I get some free time to run it under load.