Bogs down when I give it the business...

I know this is a typical problem, but I cannot find the exact problem searching around.

I have a 69 skylark 350
Changed out a 2bbl to a 4bbl
The carb was rebuilt by myself using cliffs book.

It idles well in park and drive, throttle responds well just easing into it.

But just when I give it full throttle to get going it just bogs and doesn't go anywhere.

Is this something where my timing is off and is not really a carb issue?

Vacuum is measuring around 16 or 17.

Anything more I should provide to narrow down this issue?

And of course any help is appreciated.

 

Try tightening up the secondary air door. It may be opening too soon.

 

Ok, the secondary doors get stuck and don't move as freely as I would like as well. Is there something I should check to fix that issue as well?

 

getting that door to open properly is the main key to eliminating the Quadra-Bog

... isn't it covered in the book ?

 

I do want to be sure that I'm talking about the secondary air flaps that are sticking.

 

That is what I was talking about. If too much air rushes into the engine too fast because the flaps are opening too soon the car will bog. Tighten up the secondary air flap spring about a 1/4 turn at a time and see if it gets better.

 

He's also talking about the flap "sticking." Under certain choked conditions the flap is locked shut as it should be.

 

Ok, well I took apart the secondary flap, pulled the shaft and cleaned it. That's good now, turns freely. But now, since I'm an idiot I went to install the spring and lost it. Son of a @#&$@!# so, now I have to order another one and try to install it again.

I don't think the spring was ever hooked up correctly, so might've been my issue. Sorry for bothering you guys, I think I was just being lazy.

There was never any tension on those flaps to go back closed.

I'll try to keep you updated on the progress once I get the springs in. (I ordered a few extra)

 

Ok, got a spring put in. The flaps seem to open correctly. When its in park in the garage and I give it throttle everything seems fine. But, when I take it out on the road anytime when I think the secondaries should be opening it starts choking and bogs down whether I get on it or ease into it. Is this something I should just take to a shop to get figured out? Too many variables?

 

I had a similar problem a while back. Actually, it was this issue that convinced me to join this board. Changed fuel lines from tank to carburetor; tried three different new carbs; changed all vacuum lines; and on and on... It was the timing. Trouble is, that was my car, not yours. So that is my $0.02.

 

Also had a similar problem, ended up being a wrong gasket between the air horn. I used Cliffs book as well but installed the wrong part from a universal kit, no amount of secondary spring adjustment helped when i was leaking fuel in the wrong places.

 

So many things it could be. Check to make sure that the secondary’s are opening. When you rev the engine do the upper flaps try to open? Maybe post some pictures of the carb, maybe someone will spot something. Are you getting a pump shot when you hit the accelerator?

 

take the carb off the car adjust the secondary with the allen wrench then put a penney on the secondary flap. if it opens when you put the penney on it, it should not bog. By the way an old friend who works on these carbs said thats the trick. It worked for me

 

When I rev it the uppers do open up. I'll get some pics tonight.

I feel like you were channeling your inner Yoda with that first sentence. Haha

 

Ok here are a few pics. First is car off, second is on, cold, in park and third is on, warmed up and in park. Should I provide more/different pics?

And how bad is it?

 

Dan, looks like the front choke pull off vacuum canister is old. Did you check it to see if it held vacuum? Most old ones don't. I always replace them when I build quadrajets. That can cause your problem. The rear flaps should not open when opening up the throttle while just sitting there. Maybe slightly if at all. They open up when under a load, based on the air needed. If they open up easily, you need to tighten the screw more to tighten the spring.

Also, make sure you secondary plastic cam is installed correctly and not broken. Rear flaps opening should lift the rods.

Good luck. Keep posting. You will get it.

 

I did check the cam and it looks to be in good shape. I'll check the canister and probably just replace it with a new one and new tubing. You're talking about the yellow and black one correct? I thought about doing that anyways. I will update once that is replaced. does the rod off of the canister look to be in the correct location?

 

I am going to say that canister is your problem. At idle, it should be sucked in and hold the secondary flaps closed. At full throttle, or heavier acceleration, it will release slowly and allow the flap to open. Right now, you have no restriction and the flaps open way too quickly causing your problems.

Looking at your pictures, the canister has not pulled the arm in, so it isn't working. You did mention the engine was running in the second picture, correct?

 

Yeah the last two pics are of it running.

So the canister will move the rod towards the rear of the car then the air flaps will open on vacuum? The rod isn't supposed to open the flaps?