Need help with carb...please....SOLVED!!!

[jode]

I just finished the install of my new Performer intake manifold (#2131) and a Carter AFB (500 or 650 cfm or something) that a friend gave me. The Carter looks pretty new (for what that is worth) and is in very good condition externally. The carb was supposedly rebuilt a year or so ago, and was then run successfully on several vehicles before being given to me. The installation went smoothly, but when the moment of truth came around (firing her up) I was seriously let down.
It starts up fine on ether and runs great at a good low idle with no loping or anything...for about 5-8 seconds and then it dies. After I ran out of ether (thinking that it was just taking a while to get the gas lines and carb bowl filled up with gas), I continued to be able to get the vehicle to start, idle smoothly, and then die after 6-8 seconds.
I then ran the gas line into a container to assure that gas was being delivered. It was pumping just fine, so I know the carb is getting good gas. I then pulled the little filter screen that is right behind the gas inlet in the carb, and it checked out fine.
I also dialed in the adjustment screws on the front of the carb 2 full turns (1/2 turn at a time, checking for improvement with every half turn) with no noticeable difference.

Does anybody know what is going on with this carb? It seems like it is gas starved. Could this be that the external screws need more adjusting? Could the float be stuck? Does the thing need a rebuild? Are there any other external adjustments that can be made?

The Carter is supposedly the same as a Holley right? I have a couple of books on Holley building coming in from a local library that should be here in a few days...are those going to be of any help?

This is really starting to get old...I been messing with carbs for like 4-5 months now trying to get my beast back on the road. Sorry this is so long, but I really got to get this figured out ASAP...we have a baby due anytime now and having 2 vehicles at that time would bring a lot of peace of mind to my wife while she stays at home if she had a vehicle there...just in case.
Thanks

[ March 08, 2003, 06:22 PM: Message edited by: jode ]

[dublt]

1st, and lucky fo you, carters are NOT like holleys. But problems are relatable. Howlong did this "rebuilt" carb sit around? Iwould guess that the needle is suck in the seat and not allowng any fuel in. Maybe float's binding. Take the top off and have a looksee.

[kidatforty]

It sounds like it's running on the ether you're administering.( as you probably assume as well).Without the engine running look down the carb throat and crank the throttle and see if you have fuel dumping from the accelerator pump discharge nozzles. If so, then you know that you at least are getting some fuel in the bowl. If not, then no fuel or you have pluggage in there somewhere. Important key question: Can you keep it running by constantly pumping the pedal? If so, then it would be something with the main jets, float level(shouldn't have changed since last owner),intake leak. You're not looking at external adjustments unless it runs good except for idle. Play with it and keep posting as to your progress. I wish I was there to help.Good luck.

[oddfire]

The Carter afb is the same as an Edelbrock. The two screws up front are the idle mixture screws. About 1 1/2 to 2 turns out is where I got mine set. I agree with Kid, with the motor and air cleaner off, look down the throat of the carb while working the linkage on the right side. You should see a squirt of gas if the float bowls are full. If no gas, and you have gas flow on the carb side of the filter, take the top of the carb and see if there are any blockages to the needles. These carbs are very east to work on so dont worry to much, just remember how it all goes together.............phil

[jode]

Originally posted by kidatforty:
Important key question: Can you keep it running by constantly pumping the pedal? Answer = no

Pumping the throttle actually makes it worse (die faster). i am assuming that the reason for this is that opening the butterflies allows what little gas there is to be burnt quicker.

I wish I was there to help.Good luck.Me too ;)

Originally posted by dublt:
Howlong did this "rebuilt" carb sit around? Answer= unknown :(
6 months to a year? ...maybe? I think the friend that gave it to me is in jail, so I cant ask him...he jsut dissapeared one day...

Take the top off and have a looksee.Is that a good idea seeing as I do not have a new gasket to put in there when I put it back together? the only reason I ask is that I have only ever taken apart two carbs...both were MC 4350s, and both never sealed again after I pulled them apart. :rolleyes:
Hopefully the Carter is a better carb than the MC4350s, but I am a little worried about pulling it open since it don't leak now :(

As far as the float being stuck, it shouldn't be. When I had the carb off, I could hear it flopping around in there when I turned it upside down (sounds like a brass one).

The idea about a stuck needle sounds reasonable...

Thanks for the help...I'll keep you updated with the progress...

[ March 04, 2003, 10:36 PM: Message edited by: jode ]

[oddfire]

you wont need another gasket unless you rip that one cause the gasket is above the fuel level........phil

[jode]

Interesting discovery!

I went out and looked at what happens when the accel pump is worked....

Gas shoots out into only one of the venturis when I work the throttle!

So I guess that is problem # 1
However, this shouldn't necessarily be the root cause of my problems should it? If my assumptions about carbs are correct, those accelerator jets only squirt when acceleration is needed. They shouldn't be causing the idle to not work...even if neither of them worked right?

However, it is becoming obvious to me that this carb too, is going to need a rebuild...if one of the squirters is plugged, who knows what else is plugged.

What are the chances that a Edlebrock/Carter rebuild kit is cheaper than a Motorcraft4350 rebuidl kit...the poop is gunna hit the fan when I tell the wife I am going to have to buy ANOTHER carb rebuild kit :rolleyes:

[jode]

Oddfire...you live near Placerville? My bro lives there and we will be doing the Rube as often as possible this summer...my bro will prolly be on it every wknd...looks like your rig is up for the task...maybe we should try to get a run set up? He drives an XJ, and my $$ situation will prolly keep my from driving mine that far, so it wouldn't be pure FSJs, but it would be fun to get to know another IFSJA member...and maybe some other members would be interested too...

Originally posted by oddfire:
you wont need another gasket unless you rip that one cause the gasket is above the fuel level........philIf that's the case, then I'll see about pulling it all apart on weds or thurs...maybe I'll be able to get away with rebuilding it, without buying the rebuild kit. (fingers crossed)

[oddfire]

buy a cheap vacuum guage, like $20., and put it on a manifold vacuum source and see how it reads. This will also help you dial in your idle mix and timing..............phil

[jode]

Originally posted by oddfire:
I'm pretty sure ther is only 1 squirterThen we are not talking about the same thing.
the squirters I am talking about are located in the exact same place as they are on the MC4350. They are located on the inner wall of the two primary venturi bowls...about 1/4 to 1/2 inch apart from each other, and pointing slightly toward the front of the carb (more like pointed towards the front of each front tire)...they are symetric. I can see them both, it is jsut that one of them is not squirting anything. :confused:

[jode]

Originally posted by oddfire:
buy a cheap vacuum guage, like $20., and put it on a manifold vacuum source and see how it reads. This will also help you dial in your idle mix and timing..............philWouldn't it take a vac leak the size of texas to make it run (or in this case, not run) so poorly?

I do need a vac gauge, but I can't see as how that could be the source of my current problems...but then again, I could be wrong.....

[oddfire]

yea I live on the other end of the Rubicon. I'm l about an hour from Placerville. Just a heads up, the Rubicon is not FSJ friendly, more suited for little jeeps with all its tight turns and rocker panel eating rocks. Lockers and GOOD rocker panel protection are a must in a long wheelbase rig on that trail...............phil

[oddfire]

ok Jode you are right, I had to run out and check my Edelbrock. There are 2 squirters. Chances are the carb is just gunked up from sitting.......phil

[jode]

So...what are you trying to say? ...are you in? or are you in? :D

[oddfire]

maybe with my CJ5

[dublt]

sounds like it's getting fuel to the bowl, and the prob w/letting carbs sit unused is that the fuel does "gunk" things (ports, jets, etc) up rather quickly. A kit would be a good idea, but you could probably make it work w/out one. Who knows, maybe theres just a little debris in the bowl? Oh man, it's late and now I'm rambling. You've probably figured that out by now :}

[dublt]

Jode, what's the vedict?

[JERRY88GW]

I recently put an Edelbrock carb on my beast that's I know has been sitting around for over 3 years. Runs fine. I guess I was lucky on that one.

I would check the vacume. Did you use silicon to seal the intake ports when you installed the intake gasket?

You can get a rebuild kit for an edelbrock carb for about $30. I would asume that you should be able to get a generic rebuild kit for $20 or less.

[ironhead]

Jode, if it is gunked, try some carb cleaner first, Might work for you instead of taking it apart. Not the best solution obviously, but a cheap one.
IH

[jode]

UPDATE :
I pulled the carb and tore it down. I used carb cleaner on all the small parts. I reinstalled it tonight and, after jacking with the mixture screws, I was able to get it to idle fairly well. The accelerator pump is working. I know that because if I sit there and pump the throttle, I can get the RPM's to go as high as I want. However, if I ever leave the throttle open for more than a moment or two, it quickly starts to choke the engine out. If I hold the throttle open for longer than that it kills it.
As you can see the vehicle is 100% undrivable in this condition. Does this sound like a symptom of anything?
As far as using RTV on the intake, yes, I used RTV around the waterports, and Indian headgasket shellac around all the other ports. I also put a 1/4 inch bead of RTV along the front and the back of the intake.
One other question that came up as I was in the process of rebuilding the carb: How do the metering rods get moved?? From what I can see, there is no mechanical linkage. It also seems like it can't be operated by vacuum, because there are little holes that would ruin the suction inside the little tube the metering rods sit in.
The mixture screws right now are turned out about 3 or 4 turns, and it seemed to idle better the farther I turned them out. However, it didn't seem to make too much of a difference as far as getting it to run at higher RPM's for more than a moment or 2.

Anyone? Anyone?

[jode]

Since nobody seems to be on ifsja at this hour with the answer to my question, I have been doing some thinking...
...is it possible that this carb is set up to flow too low of a cfm?

My logic is thus:
the engine seems to not be getting enough gas
low cfm carbs dont supply much gas (right?)
I must have a low cfm carb

I know, that is pretty crappy logic, but I am pulling my hair out here trying to figure out what the heck is going on....
:confused: :rolleyes: :mad: :( :confused:

[jode]

:confused:
BTT

[jode]

Is this thread getting so long that nobody wants to read it any more? Maybe I should start up a new one?
BTT

[oddfire]

A 360 will run on a 2v 500cfm without a problem.
Did you blast out all the small passageways with the carb cleaner?
Have you checked for vacuum leaks with a propane torch? Are all vacuum ports not in use capped off? Are vacuum lines in good condition. Just for testing, cap off all of them on the carb except distributor advance line, that way you can rule out cracked vac lines under dash, at tranny, at brake booster ect. Have you checked the float levels? on an Edelbrock you take the top of the carb off, flip it upside down and slip a 7/16 drill bit between the float and the carb top. This is where they should be set. Not sure on the AFB, but it is an Edelbrock clone. Idle mixture at 3-4 turns out seems a little rich to me. I would put a vac guage on it and see what its doing. A vac guage is also a pressure guage that you can put on the fuel line to see if the fuel pump is putting out good pressure. {mine just died on my wag on tuesday, $28. at NAPA} Have you tried to advance the timing and see if it makes a difference?........running out of ideas except getting a new carb................phil

[ March 06, 2003, 05:05 PM: Message edited by: oddfire ]

[jode]

Its a 4v on a 401. The cfm is unknown.

Did you blast out all the small passageways with the carb cleaner?Yes...repeatedly until the carb cleaner shot through without obstruction (2 cans worth)

Have you checked for vacuum leaks with a propane torch? No. Does this problem sound like a vac leak, or are we shooting in the dark on this one? I'll go out tonight to see if I can find any vac leaks.

Are all vacuum ports not in use capped off? Are vacuum lines in good condition. Yes

Have you checked the float levels? on an Edelbrock you take the top of the carb off, flip it upside down and slip a 7/16 drill bit between the float and the carb top. I haven't...I wish I would have known that last night when I took the whole thing apart...I'll try it after I check for vac leaks as is.

Idle mixture at 3-4 turns out seems a little rich to me. turning the screws out makes the mixture richer? That explains why it ran better when I dialed them out. It seems like this carb is not feeding the engine enough gas.

I would put a vac guage on it and see what its doing. That sounds reasonable, but I don't even know what I should be looking for with it. Supposing I go buy one, what would I look for with it. What should it read ideally, and what does it mean if it reads other wise?

see if the fuel pump is putting out good pressure. {mine just died on my wag on tuesday, $28. at NAPA} It seems like this scenario is unlikely seeing as everything was fine when I pulled the thing apart. I was attempting the opriginal rebuild as "preventative Maintenance" and it ended up biting me hard in the Keister :mad:


Have you tried to advance the timing and see if it makes a differenceNo. Why would that make a difference? I know that the timing now is the same as when I first pulled it apart and it ran fine then.

Thanks for all the suggestions. I REALLY appreciate them ALL. Hopefully this won't come down to a new carb, and hopefully I don't discover that I installed the manifold incorrectly. Thanks a million for your time. smile.gif

[oddfire]

OK lets start over, your original post said you just finished installing the performer intake and carter AFB. Is this the first time you have run it since then? If so you will have to adjust your timing because the performer will affect the way your engine breaths. Get a vac guage, put it on a manifold vac source, dial back those idle mixture screws to about 1 1/2 turns out.
Loosen the distributer hold down clamp. start the engine. the vac guage should read steady at between 17-21 hg depending on your altitude. if it fluctuates somethings not right. First try advancing your timing and see if it smooths out. then adjust those idle mix screws to get the highest possible vac reading. you will also have to readjust your idle speed. sounds to me like a combo of problems, timing and idle mixture and possible vac leak. The vac guage should come with complete instructions on what to do and look for..Also check that fuel pump pressure, just cause its pumping gas doesnt mean its pumping ENOUGH gas. mine ran good right until it died.....keep us posted......phil

[ March 06, 2003, 09:56 PM: Message edited by: oddfire ]

[oddfire]

propane torch trick for finding vacuum leaks......start engine, turn gas on torch, DO NOT LIGHT! pass torch around base of carb, vacuum line connections, intake manifold edges and bolts, keep gas away from being sucked down carb. If theres a leak, engine will rev up when you find it......................phil

[jode]

Thanks for the tips on the vacuum gauge and timing. I'll have to try it tomorrow. Hopefully you are right about it being a combo of small insignificant things.
Tonight I took the carb off after running it for 5 minutes (I dialed the screws out even further (5 or 6 turns) and was able to sustain a higher RPM without killing it) but it still wasn't running very good. When I took the carb off, I was careful not to spill any gas out of it and I took the top off to see where the gas level was. It was definately covering all the gas inlet ports. I'm not sure how carbs are supposed to work, but it's my understanding that the manifold vacuum sucks the gas out into the venturis. If this is the case, then having gas covering those ports should be all that is required for the carb to function. The gas level was about 1/8 to 1/4 inch above the inlets with the floats removed.
Does this sound reasonable?
I also hooked up a piece of hose to my mouth on one end and to where the gas come out in the venturi, and blew. On both sides of the primaries, this caused a bubbling in the bowl. So I know the passages are unobstructed. I also hooked the hose into the little ports that stick up a 1/4 inch through the top plate of the carb into the airfilter area and blew. This caused gas to shoot into the venturi from the primaries. If I applied continual air pressure in this location, the gas supply would run out after a short spurt until I removed the pressure. If I then blew again, it would shoot gas again. Does all this sound like a correctly functioning carb?
Is this the first time you have run it since then? Yes, after installing the intake and carb, I haven't been able to get it to run again.

Get a vac guage, put it on a manifold vac source......Will the vacuum tube that goes to the air cleaner damper valve right behind the carb on the driver side serve as a "vacuum manifold source"? If not, which one should I use?

Thanks so much for your help Phil, I don't know what I would do without somebody to bounce these ideas off. I'm learning lots and I really really really appreciate your help. I'll go buy a vacuum gauge tomorrow and perform the tests as described above. thanks again.

[jode]

ONe more thing>...... while I have the carb open, is it possible to determine the CFM of the carb by looking at the numbers carved into the brass ports that the gas flows out of the bowl through?

Main metering jets: 120 over 386 (or 380)

bridge thingy where the gas gets sucked out into the venturis (primary) says 1436

accelarator pump nozzles say: 264

[ March 06, 2003, 10:37 PM: Message edited by: jode ]

[oddfire]

It sound like your floats are good, and all the passages are clear. Are the needles free and clear? also sometimes the floats develope leaks and dont float, check to make sure they do and are not full of fuel. For manifold vacuum, I use a port behind the carb that goes to the vacuum ball on the firewall, just take the hose off and slip the vac guages hose on. You are correct on the way the carb works with the vacuum pulling gas into the venturis. So you got gas in the bowls, is it being replenished quick enough, check fuel pump pressure with vac guage. Check on carb side of fuel filter, possible clogged filter. I had one time last winter that left me stuck when the fuel filter froze into a block of ice. Good gas the company buys me!
Not enough fuel being sucked though carb, possible vac leak. These can be a bear to track down, the propane trick is the easiest way I've found. And you have just made a major change to the engine dynamics by installing the Performer, so the timing will need to be adjusted. Does the carb have a 4 diget # stamped into the base? 9605 or 9504 or 9635 or 9636 or 9637? If so what is it, and I can tell you the specs. If worse comes to worse, I gotta Edelbrock 1406 that was running when pulled from my wag that you can have for dirt cheap. also just a longshot here, is it electric or manual choke, and are you sure that its operating correctly. I hate electric chokes, thats why I pulled the 1406 off...................phil

[ March 06, 2003, 11:06 PM: Message edited by: oddfire ]

[oddfire]

also I believe the small port on the front drivers side of the carb is manifold vacuum.....phil

[Serious Johnson]

jode:

'Fraid I can't be of much technical help -- too many years and too many beers since I much messed with carbs. Here's what little I know:

If fuel is covering the jets, then it should idle fine forever and rev easily, at least a bit, no matter how low the float setting. With the floats all the way down, you should be able to drive it, but power would take a nosedive after a moment at high revs. With 1/8" of fuel above the jets, you ought to be able to rev to valve float and hold it for a few seconds.

If the floats sunk due to holes, then the motor might start, but soon die, and won't want to idle. Black smoke should be pouring from the exhaust if it runs more than a minute. Sunken floats (or leaking needle/seats) will generally let the motor develop full power if you can get it started and revved before it floods.

Bad accelerator pump seal or clogged passages will only come into play on rapid throttle opening. Even with the a-pump disconnected, you ought to be able to sneak-up on max power by very slowly opening the throttle. You could drive it like this, but your neck would get sore from the tip-in bog.

I suspect that your primary issue is beyond the carb (Wooo, wooo, mysterious music). How did it run with the old setup? Coil verified good?

:-

[dublt]

The vac gauges usually come w/a manual. Everybody NEEDS a vac gauge, it'll tel you more about the physical well being of an engine than any thing else. But how do you check vac leaks w/a propane torch? Better check float level, it regulates how much fuel is available for the engine. Timing affects all the above, remember the engine is a system thats all inter-related.

[dublt]

Jode, you got this carb used, right? Maybe it's missing some linkages?

[oddfire]

Originally posted by oddfire:
propane torch trick for finding vacuum leaks......start engine, turn gas on torch, DO NOT LIGHT! pass torch around base of carb, vacuum line connections, intake manifold edges and bolts, keep gas away from being sucked down carb. If theres a leak, engine will rev up when you find it......................phil

[1BAD401]

Joe:

Give me a call maybe I can talk you through some of this or maybe I can stop by Sunday, I'll be in Boise that afternoon. Email me if you don't have my number anymore. If you want I can take off my 750 Edelbrock and throw it on and see if that helps.......

[jode]

Travis....I'll give you a buzz...I'm trying to get it done today, but even if I do get it working, it would be cool if you could stop by.
Thanks for the offer.
Joe

[jode]

Originally posted by Serious Johnson:
If the floats sunk due to holes, then the motor might start, but soon die, and won't want to idle. Black smoke should be pouring from the exhaust if it runs more than a minute. Sunken floats (or leaking needle/seats) will generally let the motor develop full power if you can get it started and revved before it floods.Definatley not the problem. Originally posted by Serious Johnson:
Bad accelerator pump seal or clogged passages will only come into play on rapid throttle opening. Even with the a-pump disconnected, you ought to be able to sneak-up on max power by very slowly opening the throttle. You could drive it like this, but your neck would get sore from the tip-in bog.Definatley not the problem.

Originally posted by Serious Johnson:
I suspect that your primary issue is beyond the carb (Wooo, wooo, mysterious music). How did it run with the old setup? Coil verified good?
It ran fine.... :rolleyes: and let that be a lesson to you to not mess with something that is running fine.

It is starting to look like a manifold vac leak :(

[jode]

Originally posted by oddfire:
....you will have to adjust your timing because the performer will affect the way your engine breaths. Phil! YOU WIN!

I just adjusted the timing (with my newly purchased vac/prssure gauge, and the truck now runs 250% better....that is until I popped some sort of wire up in near the battery :mad: :( :rolleyes:
...but that is the source of another topic....I'll be posting the info right after I finish this, because, I am once again, without a truck....
This is getting old....

BTW,
- Vac = 15-17
- Fuel pressure = 4 (while cranking w/ the started...not at idle
- And propane didn't change the idle speed even when I aimed it right down the carb...so I can't see how it could help me find a leak...but since my vac is reading so good, I think we can rule out a manifold leak....right?