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  • Edelbrock Carter Carbs

    There is no doubt that a properly chosen Holley carb will out perform a majority of Carters. But, here are some ways to get the most out your Carter and a few strengths that they have for a daily driver.

    First the strengths. The float bowls are common to both primary and secondary, so the fuel is always fresh in all circuits. They have no power valves to blow if you get a sneeze. Another, there are no gaskets below the float bowl. Everything you do to it can be done with it on the car. The bodies are thick and stable, but a phenolic gasket is a good idea, just like any other carb. They are a very simple carb to tune, and they stay that way for a long time. Also, rebuilding one is as simple as a lawn mower carb. One gasket, an accelerator pump, maybe a float (never found one I couldn't solder up though) and possibly needle and seats. In my case I have gone as long as 7 years without even touching the carb.

    Weaknesses. You have to pull off the top of the carb to set the floats, but it isn't bad. They lack some venturi differential that the Holley has and are much more dependent on the transition circuits. This has one ramification that cannot be denied. If you have less than 10 inches of vacuum and your fuel pressure drops to less than 4 lbs or rises more than 5.5, these carbs are out of their range. They want 5 lbs for fuel constant and work best on 13 hg of manifold vacuum and up. You can tune some things to make them more forgiving, but a Holley is just a better choice there because they have more little things to tune for low vacuum engines and are better vented for bowl pressure fluctuations.

    Now, throw the hype out the window. These, like any other carb are not bolt ons. Pull it out of the box and pull the top off. Flip the top over and use a 5/16" drill bit under the floats. They say 3/8" I know but trust me, it likes 5/16" better. Don't pry around adjusting it on the needle and seats, pull the pin and adjust it off of the top. Get them square and even. Flip the top back over and measure the drop. I use a caliper and set them to 1.25". The tang at the needle and seat are where you adjust this, again square and even. If the float bowl gets that far down you need the needles nearly jumping out to fill it back up. If you are getting fuel delivery issues, it is better to increase the volume of fuel pumped than to go to a bigger set of needle and seats. The smallest you can get away with is good, it prevents hot start problems because it can resist standing fuel pressure and percolation better.

    Next put the carb top back on, put the accelerator pump linkage on in the middle hole. Back out the idle stop screw (counting the turns) until it is no longer engaging. Bend the link rod until you can measure from the tip of the accelerator pump plunger to the carb top at 3/8". Turn the idle screw back in, and it should be right at 11/32" It needs to be here because if you get the pump plunger too high, and the float level too low, the pump will sip air. This is what causes many stumbles. The relationship of float height and accelerator pump are key elements. If you go with the 3/8" float height, drop the plunger height to 1/4"-5/16" with the carb screw in. You may still get an occasional stumble. There are bigger and smaller squirters available, and they can bring into line fine tuning of both volume and timing of the shot. They can put more fuel volume in for the plunger height setting and throw in bigger or smaller drops which equates to time perceived in duration by the intake signal and velocity. The quickness of the shot is in the lever. The closest to the body is the quickest, and vice versa. Between the squirters, pump height, and lever hole placement, you should get a clean signal with no stumbles, and with the right float height and drop, with steady fuel pressure, you should eliminate the "second pump strike" stumble these carbs are known to have. There is a check ball in the pump system that may need optimizing to the passage, but with all of these other things dialed in that would be more the exception than the rule.

    The big transition circuit is the power springs, and they have to be tailored to your vacuum. A lot is made of jetting and rods, but the calibrations of jet and rod in most cases are pretty darn close, when you have the right carb for your displacement. One thing though, that 5hg orange spring is really only good if you are down at 10"-12" vacuum at idle or care about gas maileage. I have always just stuck the pink 7" spring in there in any of them, and its like grabbing a moving bus. This is confusing sometimes, but the vacuum pulls the needles down into the jet, the stronger spring lifts them sooner as the vacuum drops. The pink springs are long, but also more supple than the others in the pack, so they seem to dither the rods more sensitively. The rods by the way are two step and not tapered like a Qjet (Thanks BarryR for pointing that out to me) so they don't work much differently than a Holley power valve. So, expect the mileage to drop, the more aggressive you get with the springs.

    Next, the secondaries. The AVS being sold today is not the same AVS of yesteryear. This one has boosters instead of dump tubes. The top can be interchanged with an AFB, but you have to pull the boosters off and remove the counterweighted air door and put the boosters back. It is nice to adjust them with a screw, but it isn't really too adjustable like say a Qjet is. Its OK but I have done just as much doing the following. If you are running an AFB as is you can adjust the secondary engagement by removing the counterweighted air door drilling holes or adding weight to the counterweight If it bogs, add weight, if its flat, drill a little in it. If you overdo the drilling or need to add weight, a lead ball fishing sinker can be hammered in there and you can try it again. It is a process to do this, because it will likely need more than one try to get it right.

    Another small issue. There is a secondary lockout rod on the drivers side. If this link over centers and you hit the secondaries, it will close the choke, so check this before you install it, open the choke wide open, open the secondaries wide open and be sure the rod doesn't bind. You wouldn't believe how many of these carbs I have laid hands on that this was the only problem. Well that and having someone just bolting them on out of the box :D

    So is it worth it? It has been for me. I have tuned these carbs since they were OEM and I was little kid. I have had great luck with them through the years. I hope if you have one, that the above info helps. If you want more, Dave Emmanuel has a really good book on all Carter carbs, and I have a good friend who was an R&D engineer at Carter who developed the Competition Series, and was there back when they were developing the Thermoquad for the OEMs. I would be glad to ask him anything that I might not have run across through the years.

  • #2

    Re: Edelbrock Carter Carbs

    Re: Edelbrock Carter Carbs

    great info, thanks!

    how about the old Carter AFBs from the 70s-80s (9625 etc), do most of these tricks apply to them?

    My fabulous web page

    "If it don't go, chrome it!" --Stroker McGurk

    Comment


    • #3

      Re: Edelbrock Carter Carbs

      Re: Edelbrock Carter Carbs

      as an EFI-only guy, I find these posts by Bill completely interesting. PLEASE keep it up Bill!!


      www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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      • #4

        Re: Edelbrock Carter Carbs

        Re: Edelbrock Carter Carbs

        You will have some smog things on OEM carbs, but the CS Carters and the Edelbrocks yeah, you can dial them right in.

        There were some three step rod OEM models, some had idle screws that were adjusted backwards, and I have run across one or two that just had a single mixture screw. But functionally the set up principles are quite the same.

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        • #5

          Re: Edelbrock Carter Carbs

          Re: Edelbrock Carter Carbs

          as an EFI-only guy
          yeah, we sometimes forget that a whole generation has grown up without knowing how to tweak automatic choke linkages, play with float levels, adjust secondary opening rates, or even set idle mixture screws.


          My fabulous web page

          "If it don't go, chrome it!" --Stroker McGurk

          Comment


          • #6

            Re: Edelbrock Carter Carbs

            Re: Edelbrock Carter Carbs

            Good Job Bill, this information will help many folks.
            There are very few people in this world who's opinion I value, you are not one of them.

            300 in 1999

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            • #7

              Re: Edelbrock Carter Carbs

              Re: Edelbrock Carter Carbs

              as an EFI-only guy
              yeah, we sometimes forget that a whole generation has grown up without knowing how to tweak automatic choke linkages, play with float levels, adjust secondary opening rates, or even set idle mixture screws.


              I'm 34, so carbs were still being sold on OEM cars when I was a kid.


              However, a lot of the younger people that I help with EFI installs, have NEVER driven a car with a carb on it.
              www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

              Comment


              • #8

                Re: Edelbrock Carter Carbs

                Re: Edelbrock Carter Carbs

                Well I'm 28 and I started drag racing my old man's '69 Roadrunner in 1998 which had a six pack. My first vehicle was a 1987 Dodge Dakota 2WD that still had a carb. back in 1996. Carbs are fun to play with. Yes, some of us under the age of 40 have even changed metering rods, jets, accel shooters, set float levels, and adjusted idle screws. I have never played with any of the bigger dollar Demons and Holley's that have adjustable air bleeds and the like. Furthermore, I read in a magazine one time that Holley carbs that have a shooter size above .037 should use a 50cc pump. I told my father about that and he installed the 50cc pump on his six pack and get rid of the off the line bog. He never noticed it when it was a race car with 4.88's. But, he did notice it when he converted it to back to a street car with 3.23's. The 9 inch T/A "J" converter is what seemed to keep it from bogging out of the hole and masked the bog. After he had converted to the 3.23's it was very evident. The bigger pump solved the problem.

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                • #9

                  Re: Edelbrock Carter Carbs

                  Re: Edelbrock Carter Carbs

                  Bill, thank you for this extensive write-up!
                  I'm a Carter/Edelbrock carb-guy myself and also have done some 'stumble-tuning' aswell over time.

                  I've noticed that on single plane intakes, these carbs really respond to a 2" four-holed spacer, which increase the vacuum-signal to the carb.
                  1" works also, but not as effective. Such a spacer would also cure an off-idle stumble usually.
                  www.BigBlockMopar.com

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                  • #10

                    Re: Edelbrock Carter Carbs

                    Re: Edelbrock Carter Carbs

                    Thanks everyone. I am glad to help where I can.

                    It is very true that a single plane and 2" 4-hole spacer works very well. The 390 FE in my truck with a Holley Street Dominator, and 4.56 gears works very well with the spacer and an 800 AFB ( it was a 750, but I took the 800 AVS top and put it on the 750 AFB body for my 352, and the AFB top went on the 800 for the truck) It is just plain nice. In fact both of them are seamless.

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                    • #11

                      Re: Edelbrock Carter Carbs

                      Re: Edelbrock Carter Carbs

                      ......... Furthermore, I read in a magazine one time that Holley carbs that have a shooter size above .037 should use a 50cc pump. ....... The bigger pump solved the problem.
                      Also, IMHO, anything over probably a 35 squirter, definitely over a 37, should have a hollow hold down screw,

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                      • #12

                        Re: Edelbrock Carter Carbs

                        Re: Edelbrock Carter Carbs

                        ......... Furthermore, I read in a magazine one time that Holley carbs that have a shooter size above .037 should use a 50cc pump. ....... The bigger pump solved the problem.
                        Also, IMHO, anything over probably a 35 squirter, definitely over a 37, should have a hollow hold down screw,
                        Yep my father did that as well.

                        Comment


                        • #13

                          Re: Edelbrock Carter Carbs

                          Re: Edelbrock Carter Carbs

                          Thanks for another great post Bill.

                          I'm 37 and was the only kid in my highschool autoshop class that took the extra time to read the holley carburetor and manifolds book, among others, and I had probably rebuilt 50 carbs before I graduated high school. I used to work at an auto parts store (anybody remember Giant auto?) we used to get a lot of holley's returned because guys could not make them work "out of the box" my manager would let me buy them for the $50 core return fee, then I'd go through them and re sell them to folks on the side for $100 or $125 - most were the garden variety 600vac.

                          I agree with you 100% on the edelbrocks - they are unbeatable for a daily driver or boat - but won't make the power or be as tunable for a big cam'd race engine.

                          I've gotten my first couple Demon's lately - and the billet machining is impressive - I like the clear float bowl sites, they come with the powervalve protector already installed in the base plate, and the four corner idle is nice --- however -- the IDLE EEZE base plate is a HUGE improvement over the baseplate with out it (I have one with, one without) and on the engine I was trying these carbs on - the four corner mixture screws were set much much leaner than the typical 1.5 turns out on a 2 idle mixture screw carb -- I had a hard time getting the non idle eeze plate carb to idle stable, both worked great on the strip.

                          I have heard several complaints about Demons - some folks have had a lot of problems tuning them and have returned them multiple times before getting one that worked right -- however, we all know that it's easy to blame the carburetor when the distributor or a vacuum leak or some other problem is the route cause behind the driveability problem.

                          Bill - keep these posts coming - this is the greatest thing about these forums - we all learn from eachother!!!
                          There's always something new to learn.

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                          • #14

                            Re: Edelbrock Carter Carbs

                            Re: Edelbrock Carter Carbs

                            Thanks Bill. That's the kind of simple info that many need. I learned 75% of that the hard way and still just learned a couple things. Thanks again.

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                            • #15

                              Re: Edelbrock Carter Carbs

                              Re: Edelbrock Carter Carbs

                              Of the two brand new Demons I've installed and tuned, both had machining trash in them, both needed to be disassembled and cleaned, but both worked awesome afterwards. 8)

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