62 Carter AFB 340 hp

[Robert I.]

1. Shop number 1 rebuilt the carb.

2. Shop number 2 said the carb was junk. he bought 2 or 3 AFBs off of Ebay and put them together to make one working carb. Except it didn't run well. It doesn't have an exhaust,he thought it needed the back pressure.

3. the mechanic that installed the exhaust thinks he found the problem. Without the air cleaner it runs fine. the choke is attached to a shaft and there's a lever at the end of the shaft.With the air cleaner on, the lever is pushed down. I thought pushing it down closed the choke, but from my photo it looks like pushing it down would open the choke.

Thoughts?

Is that lever installed wrong?

[Tim S.]

Re: 62 Carter AFB 340 hp

Here is how the choke linkage is configured on mine. Works perfect

Tim

[Duke W.]

Re: 62 Carter AFB 340 hp

First off, ENGINES DON'T NEED BACKPRESSURE! That myth has been around for decades, and it just won't die.

Does the ST-12 manual have any info on the '62 AFB?

The 1963 Corvette Shop Manual has an excellent section, and though the 1962 3269S version is slightly different than the '63 3461S, they essentially function the same way. Since your carb was assembled from a basket of parts, look at the lower RH front corner of the main body and report the model number and data code.

When the engine is cold and you execute the cold start procedure, you first floor the throttle. This causes the thermostatic spring in the choke housing to close the choke valve completely. The left side of the choke shaft raises the link to the fast idle cam that sets the fast idle cam on the high step, so the index is aligned with the center of the fast idle adjustment screw. (Bend the link as necessary to achieve alignment.) That connection between the choke valve shaft and fast idle cam link is circled in red in the photo, and it appears it might be improperly configured, meaning it was improperly assembled.

When the engine fires the choke vacuum break piston opens the choke valve slightly (how much and how to adjust is in the service documentation), and once the engine warms a bit if you open the throttle the fast idle cam will back off and fast idle will drop a bit, and this repeats every time you open the throttle until the engine is warmed up and the fast idle cam fully retracts so you are at normal hot curb idle.

The choke vacuum break is the primary problem associated with AFBs. I gets sticky which can keep the choke from fully closing on a cold engine making cold starts difficult, and I believe those Micky Mouse OE oil wetted air cleaner elements were part of the problem because oil would get through and then cause dirt to gum up the vacuum break piston. It's easy to fix by just removing the choke housing from the carb, dissembling and cleaning, but you need a tiny o-ring to seal the choke vacuum break passage between the choke housing and main body when you install the choke housing or you will have more problems.

It sounds like the guys who worked on your carbs are morons, but since these cars are simple, if you can put together something from Ikea, AND you have the readily available service documentation you can overhaul any old carb yourself. The biggest problem with DIYers is that they start these kind of projects WITHOUT the proper documentation. thereby earning the call sign "bubba".

I hope you have the other "parts carbs". If so, you should have enough to build a decent one, but maybe the only problem is how it was assembled. Also, buy a few "zip kits" for the AFB. Who knows how long they will be around.

Duke

[Robert I.]

Re: 62 Carter AFB 340 hp

I printed out your photo and took it with me to the shop. The little lever on mine was just installed upside down.

|Thanks

[Robert I.]

Re: 62 Carter AFB 340 hp

I printed the photo from the previous post and took it with me. It appeared to me that the lever at the end of the choke shaft, was installed upside down. The mechanic turned it 180 degrees and now it runs fine, even with the air cleaner installed.

He sent me this video: https://www.youtube.com/watch?v=Ms768ZCZLXA

The original air cleaner is signed by John Fitch.john fitch.jpg