Technical Changing jets on a Carter/Edelbrock Carburetor

Stock jetting on the 9605 is .098 jet and .047/.069 (4769 stamped on rod, if I'm not mistaken) metering rod. You might check and see if it's been changed from that and use that as a baseline. Secondary jets are .095 stock.

 

Get the nozzle kit for it, it is a pack of 3 nozzles.
I have a Edelbrock 1411 on a dodge 383 and went through the same thing with the mid-range flat spot.
I went back and forth with metering rods and messed around with the secondary springs.
In the end I ended up with the pink springs, 110 main and secondary jets with the .43 nozzles, and accelerator pump set on the performance setting flat spot is now gone and pulls all the way through the power band.

 

If the carb had other than stock jets and rods in it when you got it, you might try going back to stock and see how it works, just as a baseline. Be sure to adjust the float level carefully.


Also, if you want to have some real fun, get a wideband O2 sensor on there....and beware that when a carb is working right, the numbers will be a bit wonky compared to what you think they ought to be. You need to make it drive well. The wideband can tell you when it's way lean or way rich. Kind of rich is normal for most performance carbs.

Another thing...timing curve is pretty important, if you don't know what it is, then you need to do some checking.

 

Is this a picture of the carb in question?

In this picture at least, it appears to be missing the "S" shaped link that connects the accelerator pump lever to the pump plunger. I could imagine that giving you a stumble or a mid-range flat spot.

 

hell yes.

 

What do you mean wonky? I've been alternately trying to talk myself into, and out of, a wideband analyzer, prices have came down a lot, but they aren't giving them away either. Well two of them actually, now that I have dual exhaust? Need an O2 sensor in each pipe?

The old school way was to jet down till it bucks or "lean surge" on the highway, at cruise. Now, that's not a "best performance" adjustment to be sure either. And they looked at plug "color", which I'm told with modern gas isn't as useful as it once was.

My truck has gone from black, gas soaked oily dripping deposits on the plugs (bad!) to a white insulator with a little spot of tan, but don't want to nuke a piston or burn a valve either. Runs great, if a little weak with the OEM style carb. Fuel mileage is probably almost double what it once was or close to it.

How would a wideband though, get any closer to optimum than the old schoolers could, practically speaking? Let's leave out the drag racers and trying to improve brackets by tenths of seconds or whatever for the moment.

 

It just lets you see what's going on instantly. A plug reading will not tell you what the mixture is at any given set of conditions, the wideband will. You only need one.

by wonky, I just mean that you might think it's odd that you can have nice white plugs while the meter shows you're running 12:1 afr most of the time....that's kind of rich...and you'll see it lean out under conditions you think it should be getting rich, and vise versa. It's entertaining, to say the least.

 

Must be why them fancy new car have them computers to interpret the readings and make adjustments.

 

I just rebuilt an old Carter 2bbl for a guy's '56 Willys pickup and it was missing that link that ClayMart mentioned - made a big difference in how it worked. Of course if that's not the right picture................................

 

I was just looking at this thread that the OP started a couple of weeks ago...

http://www.jalopyjournal.com/forum/threads/carter-edelbrock-carburetor-info.1012863/#post-11440919

...And was refreshing my brain about how things were laid out on these old AFB carbs. So I made the assumption that this was the actual carb he was working with. The picture is a bit dark and I was surprised that I even noticed that the "S" link was missing. It looked like it would still move the pump plunger some but that it would push it toward the rear of the carb about as much as it would push it down.

 

The link for the accelerator pump was there, the picture was sorta dark because when I started that post I wasn't sure if my old Carter and the newer Edelbrocks were interchangeable. I've learned a lot about carburetors in the last couple of weeks, a lot of helpful, knowledgeable folks able to lend a hand here and I certainly needed all the help I could get.

Squirrel's comment on an O2 sensor is right on, I'll probably keep changing jets and metering rods until I wear the screws out on the covers. I should have bought the distributor machine that I saw on a garage sale last fall but $300 seemed like a lot of money for something that wouldn't get used much.

When I was young I thought that when I got to be my dads age I'd be pretty smart, dad made it to 63 and I am now 71, he must have been a lot smarter than I thought he was because I am still not even close

 

Just keep learning that is all we can all hope too do.

 

In case anybody else needs to get stubborn carburetors apart, my dad swears by a method that was recently shared with him. Boil the whole thing in oil. They tried it on some stubborn carburetors from the 30s. They soaked it a deep fryer just below the smoking point. Everything came loose effortlessly.

 

I know! When I was 17, the old man was so stupid could barely stand to keep him around. As I got older he shaped up.

 

sounds like one of those TV commercials, "to get relief you need the penetrating heat of really hot oil" Actually it makes sense, a combination of heat and oil to soak into the threads, etc.

 

I bought the biggest crock pot they had at the second hand store here and use it and PineSol to clean carburetors - no reason that wouldn't work as well with the hot oil setup. Big investment-$20

 

I believe I will copy your idea when we are out garage saleing this spring/summer, Pine Sol sounds like a good cleaner. Now if the EPA finds out about this we all may be in trouble

 

actually in the shop we use vegtable oil in it as we can use it to heat bearings and not contaminate them as the vegtable oil is compatable with grease , plus it washes off with dish detergent if needed . ( and makes the solvent tank easier on your hands if you forgot your gloves .. )

 

You might find this handy: http://www.crankshaftcoalition.com/wiki/images/2/2e/Carterafbtuning.pdf Ideal fuel pressure is 5-5.5 psi above that it can cause a transition bog have you played with the accelerator pump stroke adjustment ? Also this: http://www.chevelles.com/members/tech/aug_tech/191.html

 

Thanks to JeffB2, good info there.