Hey Ed, I sent you an email, I got my kit. So onto the question, am I understanding you correctly that I should take out the .400 I have for the primaries, and replace them with .398's and replace whatever I have in the rear with .395's? Do the rear's not have metering rods? I havent taken that much apart YET. I did NOT get any kind of a book with the kit So I am goin to need you or RJ to walk me through this process. As I told you in my email I talked to a guy at a parts house and he told me to not mess with it, as I'd never get it right. I didnt think he was too bright, and that you were tellin me the truth. The thing dont look that complicated. Also why do these things have 2 float bowls with 2 needle and seats? As I said, I've never worked on any carb, but this is kind of a have to case.

Thanks for all the help guys

 

Since were all talking carbs, can someone tell me how to lower my hydrocarbon level? ive heard of putting 3oz of acetone to every 10gallons to clean up the combustion process and burn the unburnt fuel but thats a temp fix and i need a permanent fix. any ideas?

 

You need to find out your A/F (air fuel) ratio. Theoretical is 14.7 to 1. anything between 13-15/1 at idle is what you want. < 13/1 and you are too rich, >15/1 you are too lean. Adding acetone or other solvents decreases the theoretical A/F to ~ 14/1 so the engine is basically leaned out by their addition to your tank, a bandaid fix.Other sources of HC emmissions is dirty/worn/wrong heat range sparkplugs, worn rings leaking oil into the cylinders, leaky valves, plugged muffler/catalytic converter, improperly set ignition timing/mechanical/vacuum advance. A cylinder leakdown test will tell you the health of your engine's rings and valves.

 

Terry, I'm in training these two days for my job so I'm not at home. Check what size jets are in your carb. If the .400's are in there. Yea, pull them and put .395 in the secondary and .398 in the primary. The secondaries don't have metering rods, because the secondaries don't upon until FOT (full open throttle). Go from there! Try those and see what happens. You'll more than likely have to adjust your idle mixture screws after changing the jets. two adjustment screws in front of the carb.

 

Hey Ed, I was afraid you got mad at me Anyway, I took it apart tonight, and I do have .400's in the front and .395's in the rear. I was thinking about putting the .395's in the front for primaries, and putting .392's in the rears? I also found alot of crud in the bowls of the carb. Probably left over's from a bad gas tank in the past. That problem is GONE, but I was also wondering how to adjust the floats? You said they are supposed to be 5/16" from the TOP of the carb? Do you bend the hinge part to achieve this? I might have knocked them out a little when I took the top off the carb. The gasket was stuck a little?

Also on the springs, I have the orange ones now, and according to my "chart" on the box, they are in the middle. If I want to go leaner do I need shorter springs?

Thanks so much for all your help and PATIENCE I'm a carb dummy!!

P.S. when I took the secondary jets out they looked kind of cruded up, could this hurt anything but WOT?

Thanks again!!

 

Terry - you do just bend the hinge to adjust the float level. Glad you'll be on the road soon, that truck is way too pretty to sit in the garage.

 

I recall a lot of folks changed to 500 CFM models on the smaller smog engines because the 625s ran fat although they probably didn't try very hard to work out the issues.

You need to get a listing of the Jet and Metering Rod numbers and sizes. Federal Mogul printed an outstanding "Carter Competition Series Service Manual" (Form #3703A) but I'm sure other sources exist.

Here's what I did. It sounds complicated but it's actually easy once you enter the data.

1)
Set up an Excel page with all the Jets listed by part number. Be sure to enter the orifice size in its own cell. Then enter the formula to calculate the "Area" of the Jet Orifice. BOLDface the parts you actually have and use a regular font for those listed in the book you don't have. (I'll tell you why at the end)
2)
Copy these listings for each Jet size for as many Metering rods as you have.
3)
Do the same listings and calulatons for your Metering Rods. The rods on an AFB are 2 stepped, so you need to calulate both diameter areas.

The Metering Rods are spring loaded to fit inside the Gas Jet diameter. So in effect, once the rod is installed, the clearance between the two determines how much fuel gets through. Without much vacuum (low speed demand), the fatter portion of the rod is resting in the jet keeping the gas flow at a low rate. When you step on the Accelerator, the Metering Rod raises and the smaller portion allows more fuel to get by. That is why the Metering Rods have a jillion combinations of sizes to optimize tuning for your application.

4)
Now that you have the various "Areas" calculated you can enter them into the same rows as the Jets and enter simple subtraction formulas to calculate the "Effective Area" of Gas Flow. (A certain jet with a certain Metering Rod Diameter). You need to do this for the Low and High Vacuum combos.

5)
"Sort" the table by the "effective Areas" small to large (Lean to Rich)

If you do this right, you will now have a graduated listing of lean-rich combinations with all part numbers ready to select from. You'll notice that between the BOLDface listings are combinations you can't try.... (becuase you don't have them) but you can buy any individual Metering Rod you need.

Saved me a lot of time at the Drag Strip. Kinda Wordy I know but I hope this might help somebody.

Dawg-a-roo

 

eman has great info here, but Terry needs this in layman terms. I'm running the 600 CFM and it runs fine. Terry, the .392's in the secondary and .395 primary might be a little too radical of a change. As a rule, you don't want drop more than .002 on a jet for adjustments. They recommend going in increments. If you still really rich, then I would try switching to the smaller jets. You also want to be aware of going too lean on the carb. That could be more harmful to the engine than running a little richer. You should see improvement with the .398 and .395 secondary. I'd explaing the metering rod diameters that eman mentioned, but it might confuse you more than you already are. Great info.... I'm saving it for future reference. I'd get some carb cleaner and spray the inside of your carb and clean the gunk out the best you can. That will hinder your carb performance for sure.

 

Sounds like you need to add a good inline filter between the pump and carb. Do Edelbrock's have a sintered filter behind the fuel line connection? Look for a large nut that the fuel line screws into at the float bowl. After unscrewing the fuel line, unscrew that nut and there is likely to be a filter element that looks like it was made from compressed tiny copper beads. If a new one didn't come with the rebuild kit go to your friendly neighborhood parts store with the old one and match it up to a new one. Watch which way it came out so you can put it back the same way. There will be a thin washer gasket for the large nut and there may be a spring holding the element in place.

 

OK, Ed I'll do it the way you said. I already have .395's in the rear so I'll just clean them up with carb cleaner and change out the primaries to .398's but that sure dont look or sound like much of a change? The thing is its a pain to take the carb off and I didnt want to have to keep taking it off to change jets. I know that's all part of it, but I dont have to like it. My .7147 metering rods look a little worn too could that be a problem?

Also 2 more questions 1: which carb base gasket shoule I use? The one that's all open or the one with 4 individual holes in it? The intake is a Edelbrock Performer which is a dual plane with a dividing line right down the center of the carb opening. Second question, what temperature should the engine run? I have it running at 180 degrees now, but it will run whatever thermostat temp I put in. Does engine temp make that much difference on performance?


Thanks

 

Terry,
One of the most common misconceptions about engines is that the thermostat controls the engine operating temp.
To clarify: A thermostat is a simple valve or gate in the cooling system line between the radiator and engine. A hot engine (at maximum design temp) is an efficient running engine so the quicker it reaches that temp the sooner it is operating at it's maximum potential. The cooling system (radiator, fan etc) is designed to keep the engine from overheating on the hottest day you are likely to encounter in S. FL, so it would not allow the engine to warm up for a long time on the coldest AM in E. Overshoe MN if the cold coolant was allowed to circulate as it does under normal conditions. Way back when the automotive engineers realized that if they could gate the coolant to keep it from circulating from the engine to the radiator when the engine was cold it would heat up quicker, then once the engine reached operating temp the gate to the radiator could be opened to keep from overheating. The method of automatically gating the coolant chosen was the thermostat, a temperature operated "gate" that opens and closes depending on the coolant temperature.
The gate is closed normally until the coolant in the engine reaches the rated temperature of the thermostat then it opens. Once it opens it no longer has much affect or function until the engine is shut off and cools down when it closes to be ready for the next time the engine is started.
It can in no practical way have any control over the coolant temperature once it opens, so changing a thermostat to one with a higher or lower rating only affects how long it takes before the coolant circulates thru the radiator. Using too low a temp rating can mean the coolant starts circulating too soon overcooling the engine and possibly causing the formation of carbon in the cylinders, sludge in the oil and poor performance. Too high a rating and the engine coolant could overheat before it starts circulating causing steam pockets, warpage, boilover and pinging.
Always use a 50-50 mix of antifreeze and water no matter where you live and a pressurizing radiator cap.
__________________

 

I have a Edelbrock 1406 and a Carter AFB sitting on my workbench side by side, and although they look almost identical I've tried interchanghing some parts like metering rods and the are different. It may be because my Carter AFB is so old and my Edelbrock is the current one being sold of the shelf today. Long Story short both Carbs need rebuilt but It looks like I am going to have to find two different rebuild kits.

 

Hey Rat Rod, my Carter aint that old. I took the top off and took the metering rods out and jets. They are exactly the same. I compared the length of the rods and all and they are the same. You may be right about the older Carer AFB's , but the newer ones are the same from what I'm seeing. I dont know where youd' find a kit for an old Carter? As I said already, I'm NOT a carb guy at all.

 

OK Ed, I cleaned it out with carb cleaner. I was surprised at how dirty it was. Anyway, when I go to measure the float level, do I measure at the end of the float or back toward the needle and seat? Since they are rectangular shaped, it makes a big difference as to the level. Do they BOTH set at the same level? As soon as I get the floats set I'm ready to put it back together I cleaned up the .395's and reinstalled them in the rear, I put the .398's in the front. I think I will change the metering rods to the 7347's since my 7147's are a little worn looking? What do ya think?

 

Typically you turn the top cover plate upside down and measure between the float and the gasket surface of the cover bend the little tab to adjust but DON'T do it by bending against the needle forcing it against the seat, especially if it has a neopene tip or it will be damaged. Hold the tab with a small pair of needle nosed (pun unintended) pliers off the needle while bending.
I found this with some info on flat level as well as what jets rods and springs originally come in the E. carb.
COMPETITION RACING SUPPLY - Buy Racing Parts Sold By Racing People - East Bernstadt, KY (Southeast Kentucky near London KY)
and here is a detailed tutorial on tuning E carbs including a table of adjustment parts for each carb:
Volvord 784VC Edelbrock Carburetor Section 2