Barfly

Carter AFB 9606 / Edelbrock #1405

Okay all you carb fanatics, give me a hand here. It's been 15 years since I've done any of this stuff and my ear is not what is used to be.

Seems up until tonight I have never really had the 4 barrel open up!
Convinced this thing was still not running like it should when I punched it down at highway speeds, I took a wad of tape and jammed it in the secondary to hold the Air Valves open. Knowing It would not run correctly I thought still it might shed some light on the subject, and boy did it ever!!!

At 50 miles per hour I punched it down and womp... nothing..... pumped it a few times and BINGO! Now that is what I imagined this 340 and 4b carb feeling like. From there she went like a mad for as long as I wanted. Let off, punch her down same thing, just died until I pumped it again.

Knowing it's the vacuum that brings fuel into the secondary it makes sense I would have to pump it with the Air Valve propped open. But seeing the difference between it propped open and the way it normally runs tells me it's not opening like it should under normal conditions.

So, after all that here is my question
What would keep the secondary Air Valve from opening and is there anything you can think of that might help the problem?

Thank you
Joe.

1966sportfury

the air valve is just counter weights, theres nothing you can realy do. the speed of air opens the four barrel, unless the "air valve" is stiff to open by hand. then something is stoping it, and needs to be deburred or cleaned,

blue 68 gts

Get rid of that thing and put a holley double pumper on it

Barfly

Budget, Blue we must think Budget

That's what gets me SF, it's free and moves rather easy with my fingers.

I did read a Carter article last night about drilling the weights that hold it closed, may give that a try tonight.

Thanks
Joe

dodgenut7

hey barfly if you cant get your carb running right send me a message i got a buddy that does nothing but rebuild holley carbs he did my 750 double pumper and wow what a difference in my dart i can see if he has any rebuilt holleys he wants to get rid of i can probably get it fairly cheap if he has one he is really good at what he does and wont sell junk

Barfly

Hey much appreciated DodgeNut. I keep ya posted.
The intake is a Edelbrock Torker 340.

Joe.

1966sportfury

but what happends if you drill to much? if it opens to quick then it will stumble, and if i remember right you chased the problem for awile

Barfly

Hey SF, ya you and I are thinking the same. I backed out of drilling it out tonight and just pulled the secondary venturies and cleaned them very very well, all the little passages etc..... Put it back together and there is no change. Tomorrow I will start with like an 1/8" bit and drill one whole on each weight and continue in very small steps.

I've had that carb apart so many times in the last few weeks I can get the air valve out and back in in about a 1/2 hour

Friday night is the next race for street legal cars so I'm chomping at the bit.
I wont take the car down there running like it is, but hopefully........

Joe.

and then there is still the gears...... I love this stuff!

1966sportfury

well kool! gonna wear the bolts that hold the carb together out!, i hope it works for you, i only have 1 1405 other wise id give you air valve outa one for a back up,

Barfly

I drilled two 5/32" holes one in each weight and put her back together.

It's hard to explain sounds in type, but before the drilling
when I punched her down at highway speed she would
kick down and take off pretty well but it sounded like a
vibration, almost like a miss but not quite.
Just kinda rough sounding.

Now after taking that small amount of weight off when
she kicks down it's smooth, very nice acceleration.
I would stop a little short of saying it's faster, it's certainly
not a slower accel but it sure is a lot Smoother,
I am very very happy with the results.

Here is the reference I got the drilling idea from

1966sportfury

well kool, least you getting figured out,

dodgenut7

glad to hear your issue is solved but if you ever want to change to a holley let me know and i can see what he has

62Furious

thanks for the document I will read it later to see if it will help and wake up my car, I am running a carter on a 400 lean burn motor

Barfly

You are welcome.

DodgeNut, I'm not out of the woods yet, just making progress, I keep ya in mind.

Joe.

67gtxclone

Good job "drilling" down in to that issue and solving it Barfly! Now you are one of the go to guys for carb questions on the forum!!!

Barfly

LOL! well I don't know about all that but thank you.

The secondary air valve adjustment did help smooth out the acceleration on the open road when stomping it down. However I am still suffering from the flat spot at take off. Last night we made progress with that adjusting the A/F mixture a little richer.

Little by little we'll get her in line, "patients and perseverance". That's what I'm telling my son anyway, while I'm cursing under my breath

Joe.