carb secondaries not kicking in

[crause]

The other day I was doing a little tuning up (cap,rotor...._) and after installing all the parts, I started up my L48 to check everything out. It started great and ran beautiful. While I had the air cleaner off, I decided to check the secondaries and make sure they were kicking in. I activated the carb with the linkage from the accelerator but the secondaries would not open. Even when I hit it hard, nothing. I opened the top butterfly and while looking down the throat, hit the gas again and I could see that the lower baffles were not opening either. Here is the question, is this because I was using the linkage to accelerate the engine or is there another problem. Let me say again that the engine runs and drives great but I don't think the four barrel is kicking in. I noticed a small diaphram on the front passengers side of the carb. does this activate the secondaries and maybe is not working? I was going to put a carb kit through it in the near future but I don't think this will effect the secondaries.
Any help?:confused


Andy

 

[Pancho]

I'm assuming this is a Quadrajet....

Follow the secondary butterfly shaft out the passenger side of the carb; there's a little interlock arm that will prevent opening of the secondaries until the choke is 'released' -- maybe the choke wasn't warmed up enough yet, or that interlock is sticking.

The small vacuum thingy is the choke pull-off; if that's not working the choke might not be releasing, which could be the problem. The pull-off should retract fully with vacuum applied.

Another possibility would be bent linkage on the driver's side that connects the primary shaft to the secondary shaft.

Also make sure you're getting full travel on the primary shaft....

//Pancho

 

[crause]

Thanks Pancho, I think the problem may have been that the engine had not warmed up and that prevented the secondaries from kicking in. I will check again with engine at operating temp.

Andy

 

[silver 80]

Q-jets vacuum operated? I thought you couldn't get the secondaries to kick in unless it was under a load? So you would have to drive it.

 

[Vettehead Mikey]

Q-jets vacuum operated? I thought you couldn't get the secondaries to kick in unless it was under a load? So you would have to drive it.

The upper plate is vacuum operated and won't open unless the engine is up to temperature AND under load. Static tests are a waste of time (and gas).

 

[drags1998]

Pancho is dead-on with his description, Check and clean all of the linkage on the carb and retry, just let it warm up first!!!!:L

 

[crause]

Ok, that is great, but one more question, I can let the engine warm up before the four barrel will kick in; but how do I put a load on the engine, which I suspect means driving it, and still check to see if the secondaries are kicking in.

Andy

 

[71VERT]

do the paperclip trick, put a papercilp on the vacuume secondary diaphram linkage up on top near the diaphram, when you take it out for a drive give it some gas and when you return see how far the paperclip moved down, that will tell you if your secondaries are opening. You may have to do it a little differnt depending on what carb you have.

 

[TOMMAY]

One thing nobody has mentioned.If your secondaries are working you'll hear when they kick in loud and clear.If you're not hearing and feeling the secondaries kick in,then they're not working.

Good Luck

Tom

 

[photovette]

I have an Edelbrock 1903 Quardrajet:

How far should the lower baffles open on the secondary side? I pulled the throttle back manually, tripped the lockout--and the lower valve is only open about 45 degrees. Should they be at 90 degrees like the primaries?

 

[motorman]

I have an Edelbrock 1903 Quardrajet:

How far should the lower baffles open on the secondary side? I pulled the throttle back manually, tripped the lockout--and the lower valve is only open about 45 degrees. Should they be at 90 degrees like the primaries?

if you have a cable throttle your throttle cable needs adjusting. go under the dash and bend the gas pedal link so it pulls the cable back farther before it hit the floor. if you have floor mats this will cause the same problem they hold the pedal from going to the floor. i have also shortened the cable where it goes thru the gas pedal linkage with split shot fishing sinkers