Technical Changing jets on a Carter/Edelbrock Carburetor

Now how hard can it be to change jets in any carburetor? Well, in this case after you set the carburetor on the bench, you take off the top, grab a screw driver, stick it in the slot, turn the screw driver counter clock wise and you have 'em out. Great theory, I can't get 'em to budge, my neighbor took a shot at 'em too, he was afraid we were going to damage the jets so we stopped. I thought about heating the jet but........with a die cast piece what would/could happen? (This is a twenty? year old Carter, base ID is 2639 9G 5S)

I am certain that I am not the first person that has encountered this problem, I just hope someone that has the solution can share it with me. Thanks in advance.

 

I'd like to know what works. I've thought of drilling them out a bit to loosen them or an easy out. But I don't want to junk one of my Carter's,


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Dennis Wilson should know

 

Start with a good screwdriver that fits the slot really well. If they won't budge,
tap on the end of the screwdriver handle while your twisting it.

 

Do you need to make such a large adjustment that it can't be done with the metering rods?

 

I don't know about those, though Holley jets need a hollow ground blade, a gunsmith screwdriver is an example of that kind of blade. It fits tight all the way across and from top down, so it won't rock or twist and bugger up the jet. This means much more force can be applied as well.

 

Take off the top? Do you mean the covers? I am Butch/56sedandelivery.

 

I've already tried the smallest diameter metering rod that came in the "Calibration Kit" and I still have a huge midrange flat spot, I had started another post trying to determine why the problem existed and all of the responses came back to a lean fuel air mixture. My neighbor and I disassembled the carburetor yesterday, soaked it in non EPA compliant carburetor cleaner from the old days, and installed a kit. The accelerator pump did work better, installed the smallest metering rod in the kit and driveability improved some but the flat spot was still there. I've spent over $100 on a kit and calibration kit, a third of the way to a new carburetor
For what it is worth my neighbor is still leaning towards an ignition issue, he is thinking of upgrading his engine to an Ignitor III from the Ignitor II and if that cured the problem he would upgrade too. I too, have the Ignitor II as an upgrade from a points distributor.

 

The metering rods are stepped. The part that affects the mid range are the top step not the lower part of the needle.
There are so many combinations of steps on the metering rods and jets that I don't see how anyone could make changes by the eyeball method. If you don't have Edelbrocks owners manual get one. It has a graph of what combination of jets and rods do what. If it's a Carter, they have a book too, but it's a little more complicated to use.

Here you go, calibration starts on page 10, but it wouldn't hurt to read the whole thing. Might save some head scratching. Check the metering rod springs too.


http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

 

There was no eyeballing method, I used a micrometer to measure the original metering rods and used the only set that was actually smaller diameter, that is why I want to go to a larger jet size to richen the mixture even more. I've also changed the springs to the stiffest to help richen the mixture even more. This carburetor came off of a BBC that came from Denver, which may explain why it is lean now AND why I broke rings in the BBC (that the carburetor came off of) many years ago and had to rebuild it. Thanks for the link, I had accessed it sometime back, but I do appreciate you listing it since I am sure that I am not the only one that can use all the information they can find.

 

Just out of curiosity what carb are you working on? What metering rods and jets were in it to begin with? What are you putting in it now?

 

The carb is an ancient (20 years old?) Carter, but......it is very similar to an Edelbrock 1405 or 1406, probably a 600 CFM unit, engine is a 331 inch SBC, 10.25 compression, Howard Roller cam, 042 heads and fenderwell headers. I just want to get the stinking jets out to try a richer tune without ruining the carburetor.

 

That works for me. Good Luck!!

 

Did you try the vice grips on the screw driver handle method ? Another method would be to stick a center punch in the jet, heat the punch so the radiate heat travels down into the jet possibly loosening it.

 

thanks for the ideas, I may try the "heat the punch" and "tap it" ideas, I think also I will take one of the new jets, and grind a screw driver to fit it exactly, or......as close as I can

 

You can buy a screwdriver made especially for jets, using the right tool is important because a buggered jet will flow different.

 

My neighbor has the one for Holley Carbs, but.......his son has it I wonder if they are "the same" or close enough that it would work, time to call my neighbor!

 

One of my pet peeves. I always put anti seize on jets when they go back in. All the tricks that work have pretty much all been mentioned already good luck.

 

Have you tried installing a stronger power piston spring? This will make the power enrichment occur sooner, possibly before the lean flat spot condition begins.

Increasing the jet size only is going to richen the mixture under all driving conditions. You may cure the mid-range flat spot but your fuel mileage will suffer to some degree.

 

I've got the "stiffest" power piston spring installed hoping that the effect of smaller metering rod and stiffer springs would "stack" enough to mitigate the flat spot. I think I will have to get a bigger hammer, the carburetor is worthless at this point, I don't want to break anything (because I am cheap) but I won't be happy until I get the jets out.

 

Get your screw driver that fits the best and smack it with a hammer you would really have to hit pretty hard to mess up the carb.

 

I've seen a soldering gun at it's highest heat range. Held to the center of the jet and held there for a few minutes, heat them up enough to remove. Joe

 

BTW , 20 years is not ancient , Cripes , I've got sweatshirts I still wear older than that !!
dave

 

For heat oldsjoe has got it right.....

 

Is there room to angle the screwdriver on the shoulder of the slot to be able to hit the screwdriver with a hammer in an unscrewing motion ? Maybe try that after the jet is heated.

 

There's not much room to get to the jets in an AFB.

I've actually used a hand held impact driver to break the jets loose in a carb before, but not an AFB. You'd need a long bit the fit the jet and that's a pretty tall order. Also need to use discretion when swatting the driver with a hammer.

 

Try squirting the jet orifice full of penetrant and letting it soak awhile and then add a little heat. Joe

 

Naw, like all guys who tune carbs, he ran holleys...

 

Good advice, I also use a square shank screwdriver with a wrench on the shank, vise grips chew up the shank of the screwdriver. Yes, its one of those 3 hands deals, good to have someone else there to tap on the end of the screwdriver.

 

OK, thanks for the many suggestions, since I had some old screw drivers I fabricated one that would fit the jet closely, just a little time on the 12 inch sanding disk gave me a good fit, I rapped it a couple of times with a small hammer and they came right out, much easier than I had anticipated. Now after I've attended to another (much bigger) issue I will be able to go back and experiment with metering rods and jets!!!

I am starting to think that I was a lot better at building cars when I was in my 30's than I am now in my 70's.