Ok, I'm real used to fuel injection. Now that I've come clean here's what I need...I swear the 4 bbl isn't opening on my 76 L48 (can't tell by the gas mileage, LOL). Can I just take the air cleaner off, push the gas pedal down and see if it is opening all the way? Does the position of the butterfly mean anything? other than this it seem to run well, just not much power but that's probably the 30 yr old cat. could that also be the reason it doesn't seem to have a 4bbl too? the cats plugged up? although it doesn't seem to get extra hot. I can remember the one on my 77 cutlass just creaking and groaning so you could tell the thing was smoking hot...but I ramble on.

 

Well, on the low power issue the cat culd definately be an issue. On the secondaries not opening, I don't think you can just ****** the throttle open sittin in the driveway and get them to open, they are vac operated. Get Lars' paper on the QJ and go thru that, you will probly find what you need to know in there

 

With the engine off,find something to hold the secondary air valve (the big butterflys) open.

Now you have 2 free hands
With one hand move the cam ( The part that the tip of the screwdriver is pointing at in the attached pic) away from the pin that goes through the shaft.
Now look down the secondary opening and work the throttle linkage by hand.
It should open ALMOST @ 09 degree angle (Almost vertical)....
This is a good static test
As far as wondering if the secondaries are open at full throttle on a running engine... all I can say is You will certainly be able to tell
There is no question as to wether or not the secondaries on a Quadra Jet are opening under full throttle as the power and the sound will change quite noticeably

 

If this is a Quadrajet carburetor the secondaries are NOT vacuum operated, they are mechanical.

With the engine off hold the secondary air door open and operate the throttle to full open. You can see if the secondary butterflies open or not. The air door above the secondary throttle blades is not connected to the throttle blades in any fashion. This makes the secondary side of the Quadrajet a variable venturi system. Fuel flow does not start until the air valve begins to open.

BigBlockk

Later.....

 

All right, this has been very helpful!

I can move the secondaries manually to full open with the gas pedal floored. I opened the air doors by hand and then pushed the throttle full open and the secondaries only come up off the seats about 10-20% tops, maybe 1/8" travel. It looks like the linkage won't rotate the rod any further.

Are there directions in nay of Lars' papers on how to adjust this?

 

Did you move the cam off the secondary lockout pin as I had posted above?

 

Yes I moved the cam "by" the secondary lockout pin. The pin on mine is too far away from the cam to lockout anything. Here's a picture...


Well, can't quite see more than just the cam/pin but it's about an 1/8" gap. i rotated this pin to see that the secondaries opened nearly 90deg. then I had my son push the gas pedal down to the floor and looked again from the other side. they were not opening. once i saw what was moving on the gas pedal linkage side i rotated that by hand further and the secondaries went all the way open. Hopefully this explanation is somewhat clear. Let me know what else I can add to help with a resolution!

 

Try pulling back on the primary throttle-if this opens the secondarys -then it sounds like your throttle cable is stretched or not adjusted to pull enough.make sure your mat is not under gas pedal

 

Try removing your floor mats...No kidding

 

Forgot to mention that. I pulled it back before I had my son push the pedal down

 

If the bracket holding the cable at the base of carb has moved forward the carb wont open all the way

 

If you turned the rod and the secondarys opened up then it sounds like your not getting enough from the pedal

Have your son hold the pedal to the floor and then see if you can get more from the linkage by moving it by hand.


Can you post a pic of the other side, with the throttle linkage showing?

 

Yes a pic would be nice.Bob a couple of years I saw a Q-Jet pillow in a catalog(really).I'm going to see if I can find it for you.It would be more comfortable than real carb your using at night. (Just kidding of course !!!)

 

Keep it up pal......... Ive never heard of Ohio but I can probably get someone to help me find it on a map, then lookout because Im gonna............. ah forget it, If its more than 100 miles from me I wont make it in my old 73'
ps: I dont use the QJ for a pillow, you know those huge secondarys... Well heres what I do..... I take the...................................

 

ok pics are always great. now that i know what to show you thngs are improving!



The air cleaner to carb gasket came apart when I took the air cleaner off last night. I put on a new one and drove it to work today. Felt like it had better throttle response but it smells like gas tonight after parking it in the garage. the smell is actually in the kitchen now. could the gasket make that much difference (old one was in pieces)? Still doesn't help my secondaries kick in but it is an observation. dang I wish i had money for FI.

I also found another piece of the gasket that I missed in the dark last night...you can see it in the 2nd picture!

 

If your smelling gas in the house I would get the car out of the garage ASAP and check for leaks both under the car, under the hood and look for fuel pooling up in the carb itself

I seriously doubt a new gasket would make any difference in performance.

Did you try this??
Maybe your lnkage needs adjusting to get WOT... cant tell from the pic

 

OK...pictures are great. You have a couple of problems that can be seen in the pictures. One is that your secondaries may not be opening all the time due to their being pressed against the side of the venturi. The rod which runs from the primary shaft to the secondary shaft has this tall bit running up from it...it is supposed to be the first thing to start opening the secondaries so that with the additional leverage the secondary plates won't bind against the inside of the venturi.


Your throttle plates are apparently not opening enough...you can adjust when the secondaries open/close with the tang on the primary shaft as well as adjust how much the secondaries open up. You can actually bend either tang for this...it appears that the tang which moves to contact the other tang is bent away from contacting the other tang...perhaps you should start by returning that tang to a more perpendicular orientation and see if that is all it takes. You may also have a weak spring on the secondaries...it is a fairly strong spring and should close those secondary plates real solid.


You can get this information in the carb rebuild kit instructions...that's what I used to double check my facts.

 

yes, i can get more by hand. it goes full open.

 

RocknRoll - great adds to my pictures. I'll get a set of carb rebuild instructions just to make sure I'm making the right mods to it. I'll try your adjustments and check back in with you guys. THANKS!!

 

Sounds like you will be getting WOT with a simple adjustment!

No offense to Rock N roll but from what Ive read thats not the proper way to adjust the secondarys unless its WAY out
Doug Roes book suggests to 0.50" between the two

I realize I bent a different part of the linkage but I believe the outcome is the same......... a super rich condition

Read this thread... I neglected to post the final outcome(sorry) but after following everybodys advice, its the best running QJ I own

http://forums.corvetteforum.com/show....php?t=1460829