josehf34

Hi guys

Today my mechanic came to check my car because the engine start to misfire again. He remove all the spark plugs and all of them were black so the conclusion is that the misfire is due to a very rich mixture and this causes the spark plugs stop working.

I already checked the carburetor and isn't idling on primaries and the choke air door is always open but when I accelerate maybe to 1500 - 1800 RPM I can see gas coming out of the primaries.

Tomorrow I'll check the jet size and post it here

Mr.4spd

If it's gone rich all of a sudden it could be blockage in the air filter housing or a plugged air filter, not real common on a street car though. Could also be a partially sunk carb float.

Hot Rod Dave

its not jet size,its a air problem lean it out adjust the air screws if you have a holley carb and its ever backfired through through the carb it will blow the power valve check that if its that rich the fumes would knock you down check heat range on your plugs also

TVLynn

Not sure what you have ? Float level too high ? Also make sure you have 12 Volts on the coil !!!

josehf34

I'm pretty sure thatt I have 12V at the coil, my distributor is HEI type so if it doesn't get 12V will start to fail and isn't failing

My carburetor is a Carter AFB

The air filter is new, is a K&N and doesn't seems to be dirty .

I'm going to check the jets and take some pictures

demetri

May be you should check under what conditions your car runs rich. May be that will help you identify the source. When an engine runs so rich, you will see visible black smoke. May be you should have somebody follow you, and see when does the car have worse black smoke. If you see more black smoke at high rpm/load, may be air filter will be suspect.

josehf34

I checked the air filter and everything is fine, no dirty and no blockage on it, but when I checked the carburetor I found a disaster inside on it, here's a picture?


Accelerator pump and meetering rods destroyed.

what could have caused this?

Where could be a recommendable shop to buy meetering rods replacement? I was thinking on www.carburetor-parts.com but I've never buyed something on this store

My actual jets size are this:
Primary: 120(48)
Secondary: 120(39)

Is this size fine or should I buy a pair of smaller jets?

moe7404

OK leave the rods IN the lid when putting the lid on? yep some one did. very very slowly straighten the rods. just eye ball to get straight, IE if it looks straight you should be ok. lid first THEN the rods.

josehf34

worth repair this rods? or will be better buy new ones like this

Is my jets size fine or should be better try with smaller size?

moe7404

ill guess the jets are ok. ill bet finding the same rod is not easy. the ones that edelbrock has will most likely not be the same size. some times close will work or not. warning do NOT change the jet and the rod at the same time. you can NOT guess at what the change is. i do have a computer program that will show the change when you do change both. but you can NOT guess at it. only change one at a time. and if a jet will not come out easy do NOT force it. the trick is use a torch heat the jet till flame color changes then dump water on it. let it cool. the jet does NOT have to be put in tight just snug is fine.

TVLynn

Those jet needles would certainly be better than the bent ones.. I would heat it a little before trying to bend it straight

moe7404

the rods are brass they will not like heat when they are that small. get a micrometer and measure the diameters. see if edelbrock has one close. i will guess the closest one from edelbrock will have a bigger diff from the power step to the cruse step, than any O.E.M. chrysler rod. an other trick is to file a flat spot on the step that is to big. a little math to calculate the area will start you in the right direction.

josehf34

I removed the jets from the carb to look the number size and they come out very easy, I don't force it so I guess everything is fine.

Now that we're talking about the meetering rods, the bent meetering rods doesn't close totally with the actual jets.



They aren't never like the closed stage of that picture, there's always clearance between the metering rod and jet. Is this normal or maybe the previous carburetor owner change jets or rods?

I've been trying to blend it again but they didn't get 100% straight so I guess will be better to buy a new one.

How can I choose the correct meteering rod? Sorry but I've never changed meteering rods

moe7404

new ones that are with in .002 inch might be fine. AFBs had two styles.
the long rods and short rods.
1. the long ones had a domed cover , long rods with 3 steps , with tall jets. it is a set
2. the short ones , flat cover , two steps , short jets. it is a set.
3. springs should be the same.......do NOT mix between sets, , you can change the the jet , rod diameter but not lengths. if you are lucky to find charts, some of the very old charts are different than the newer ones. do NOT drill out jets, the jet hole has to be very smooth any burrs could change the fuel flow. a reg drill bit can NOT make it right.. but if you have a very good reamer and are careful you could get by. be who has that many good reamers in all those sizes.

josehf34

What could be the functional difference between the long metering rod and the short? I'm going to check the number that is stamped on the rod, maybe that can help to choice a new rod.

RacerHog

This is what your looking for.....

http://www.ebay.co.uk/itm/Carter-Car...p2047675.l2557

josehf34

Nice kit but the auction has ended and I've been looking on ebay for other but I don't find it yet.

The stamped number on the broken metering rods is something like 2412. Any idea of what rod should I buy? or will be better buy 2 or 3 different rods and start the "trial and error" work?

TVLynn

Try here http://www.carburetor-parts.com/AFB-...ts_ep_298.html

josehf34

I'm waiting a response from that website

What about this edelbrock tuning kit?

moe7404

the tuning kits you are looking at have a list showing the rod numbers and diameters this way you can match the diameters. like i said before, edellbrock rods are normally have a larger difference from the power step to cruse step than most O.E.M. chrysler rods. meaning chrysler had it right to stat with. if you insist on swapping the rod and jet at the same. just calculate the area of each and and find the persent of change. substact the area of the rod from the erea of the jet this controls the fuel flow. i do have a computer program to do that. BUT normally only change a jet OR a rod at one time.

moe7404

i have been looking at the site that lynn listed for carb parts. it looks like they really know carbs. AND have some brass parts for the AFB that i thought was no longer available. DO check them out. thanks lynn.

josehf34

you misunderstood me, I was looking that kit to have multiple metering rods option because I had not found information of this rod size. The guy of ebay (ninjafuelsystems) said that the number "2412" is the old size and must be converted to a new size

I'm going to buy three different metering rods and try to find the closest possible.

Question: If a metering rod is larger and thicker will cause a leaner part-throttle cruise?

moe7404

with the same jet a larger rod will be leaner. the fuel flow is controlled by the difference in area of the rod and jet.

josehf34

mmm so if I have a larger the fuel mixture will be lean at part throttle cruise but at WOT the mixture will be normal or not?

About the springs I read that sometimes if the rod length has changed the spring must be changed too to modify the time when the rod is down into the jet. Is this true?