four barrel quadrajet question(s)

[1969owner]

i have a 4bbl quadrajet carb on my 283. the four barrell will kick in in first gear, and shread the tires. it will kick in in second gear alright. but i can not get it to kick in if i punch it in third gear. is it supposed to kick in while in third gear, or is there a prob? i have been told it is a vaccum hose issue. but i would much rather hear it from you guys. would you happen to know why the quadrajoke wont kick in while in third?

[boundstaffpress]

Sounds to me like a vacuum problem. One thing that happens on quadrajets is the throttle plate shaft gets worn and allows air to pass through. This won't cause noticable problems in lower gears where you have high RPMs, but woul be noticable in higher gears where vacuum is reduced due to low RPMs. You can check this by putting your finger over the side of this shaft while it is idling if it picks up a little this something to consider.

There are kits to drill and set bushings in these.

I'd check/ replace your vacuum hoses before you mess with this

[CoolRide]

Originally Posted by 1969owner

i have a 4bbl quadrajet carb on my 283. the four barrell will kick in in first gear, and shread the tires. it will kick in in second gear alright. but i can not get it to kick in if i punch it in third gear. is it supposed to kick in while in third gear, or is there a prob? i have been told it is a vaccum hose issue. but i would much rather hear it from you guys. would you happen to know why the quadrajoke wont kick in while in third?

The vacuum hose doesn't make any sense to me. Seems like if it is kickin in for first and second, it couldn't be a hose issue. Maybe linkage?

However I don't know much about carbs other than I always throw away the quadrapukes and put on Edelbrocks, But I also understand sometimes we have to work with what we have.


CoolRIde

[1969owner]

i dont know. its a good lil carb. but if i want to run like a scalded dog, i want it to kick in when i hammer it. my dad outran the police in my truck once...

[jhow66]

The air valves will not open until the rpm of engine is fast enough to cause the airflow to be strong enough to open them. With a 283 it will take high mph to open them. The air valves size the carb to to what the engine can use.

[1969owner]

alright, ill check the valves on the carb for air flow, and if they have no line to them and what not.

[1969owner]

but i gave 140 bucks for it new. its cool, for a quadrajoke

[1969owner]

is there any certain thing that should have a hose too kick it in at high rpm?

[rage'nrat638]

on the secondary shaft housing on the top plate of the carb..
there is a tiny screw ,
that controlls the spring pressure of the secondary butterflys.
this is adjustable..
it is possable that the spring pressure is adjusted to strong.
mark

[1969owner]

so if i loosen it up, itll kick easier? what if its too loose? hell of a ride? it might be too tight. ill get some gas tomorrow and fool with the screw you mentioned. maybe thatll solve it, i hope.

[rage'nrat638]

Originally Posted by 1969owner

so if i loosen it up, itll kick easier? what if its too loose? hell of a ride? it might be too tight. ill get some gas tomorrow and fool with the screw you mentioned. maybe thatll solve it, i hope.

you will need a jeweler screw driver,and it's not seen from the top. some used a allen wrench
i am trying to find a picture

[71-longbed]

ADJUSTING AIR VALVE TENSION
If you follow that linkage to the arrow on the left in the picture you should see a little flat head screw through the linkage bracket. You'll have to move the linkage back a bit and slide your screwdriver in through the bracket and onto the screw. Directly under the screw is a small allen head grub screw which locks it into position - it's under so you won't be able to see it but trust me it's there. You might have to get a small mirror and a light to locate it for the first time.

1) use both hands to locate the allen head screw underneath and place the allen key on it but don't turn it!
2) Hold allen key in place with your left hand while using your right hand to place the flathead screwdriver onto the adjusting screw.
3) Making sure that you don't let go of the adjusting screw, loosen the allen head grub screw a little bit. Just enough to allow the screwdriver to turn the adjusting screw. The adjusting screw holds tension from a spring so if you loosen the locking screw without holding the adjusting screw it will unwind like a window blind and you'll have to start over again from zero tension (which is another story).
4) loosen the adjusting screw no more than 1/4 of a turn and preferably 1/8 at a time and tighten the locking screw. You won't be able to see how the air valve butterflies "flop" until you take the screwdriver out and allow the linkage to go free but I suggest that after 1/4 turn you go out and drive it. It should flop open easily but also have enough spring pressure to make sure it closes or it's bog city for you. Floor it under all sorts of conditions and keep loosening it until it starts to bog when you floor it then come back 1/8 of a turn from that point. If you can loosen it 1/4 to 1/2 a turn and still not bog then it needed it. If it bogs on 1/8 to 1/4 of a turn then it was about right and you should leave it. In any case, loosen it until it bogs and 1/8 turn back from that and you should be right. I'll be very surprised if you loosen beyond 3/4 of a turn of where it is now. The leaner the rods the less quickly you can open the airvalves without it bogging. When you have a loose air valve flap you better have the rods to back it up (which we have with the AX/B combo) because there's going to be a whole lot air coming in pretty quickly and it's going to need a lot of fuel.
I hope you understand all that because I typed it all off the top of my head without looking back.

..not my words .. just a copy and paste

[1969owner]

thanks a lot 71-longbed. ill try that later. im going to look at a tailgate today.

[VetteVet]

A wise man once told me "if it ain't broke don't fix it ."

[1969owner]

good point......but i need more kick than what it has, i screw it up, ill get a edelbrock next time, or a demon

[JAKES 68GMC]

holley 600 would solve some problems.

[1969owner]

sounds good, i always liked holley, right behind edelbrock