2 Barrel Carb 400

[Als73charger]

  Now that I have my car finally running, there is a problem when I try to accelerate. The motor will hesitate and try to stall. Do I need to re-build the carb or is there an adjustment that can be done?
Any help is appreciated. Al

[Cooter]

While AOT of thigns can give you the symptoms you've described.. When dealing with the carb as I assume it's never been rebuilt, yes, sounds like an accelerator pump problem...Time for a rebuild...Have you checked out everything else like timing, plugs, wires, etc...?

[Als73charger]

  I have installed new plugs, wires, rotor and cap. I just have to coax it to get the rpm's up. She idles real nice and once the rpm's are up, she sounds real smooth.

[71383bee]

Cooter is right.  Check the timing before pulling it apart.  As a rule I usually start by setting total timing at 34 to 36 and see what the motor does.  If it lags the starter or has detonation then you need to back down.  let it idle down and check to see what initial is at.  Don't go by what the factory says.  For that year they would want something like 0 or 5 degrees advanced which was more for economy than performance.  I have found that even lowly old 318's will love a little additional timing and wake it up.  I like around 16 to 18 initial personally. 

Let us know if you do not understand initial  and total timing, etc.  Not a lot of noob's know how to set it so its okay to ask. 

I would agree though that the carb may need to be gone through, but timing can hide so many issues. 

[Als73charger]

 Ok, confession time.....I am a Noob! Tell me what I need to know about timing, the lingo etc. I do not have a timing light, but figure I probably need to get one. How much of this, if any, can I do by "feel". I have played around with the carb last night and that seemed to make some improvement but the sputtering is still an issue. Thanx for all your guys help

[Cooter]

It sounds to me like you need just a little more timing in the motor...If it's lazy coming up to RPMs, then try turning the distributor till you hear a slight increase in idle...Then try it and see if it's better...To set the timing, you WILL need a light, but there will be a few marks on your bottom balancer (Thing behind the bottom pulley) will look something like this...ATDC10....5....0....5....10BTDC One way is After top dead center and the other is BEFORE top dead center....Before= Advanced ....After= Retarded timing...

[71383bee]

Ok, confession time.....I am a Noob! Tell me what I need to know about timing, the lingo etc. I do not have a timing light, but figure I probably need to get one. How much of this, if any, can I do by "feel". I have played around with the carb last night and that seemed to make some improvement but the sputtering is still an issue. Thanx for all your guys help

No problem...go get your self a DIAL BACK timing light.  I don't just suggest this it is a must for accurate timing on these cars.  On perfromance motors we play around in settings way out of the norm than stock factory settings and to do it properly its well worth the few extra bucks to get a good dial back light.  The light will have a dial (duhhh) on the end that you can use to add degrees of advance into the timing mark. 

So with you dial back lite and the VA disconnected and port plugged set initial at say 18 degrees by turning the dial to 18 and loosen the distributor hold down with a 1/2" wrench and gently twist the dizzy.  IF right it should pick up in idle and your engine will begin to purr like a kitten.  Adjust the dizzy till the mark lines up with the 0 (remember its not really at 0 because the dial back light is set at 18 which means 18 degrees of advance is added to the lite) hold the dizzy with one hand while tighten the hold down with the other.  After check again to see if it didn't creep.  That is a good first step.

Total timing is the maximum amount timing put into the motor.  Add the mechanical timing to the initial timing and you get the total timing.  Most dizzys have anywhere from 15 to as much as 30 degrees of mechanical timing that is added into the motor depending on the size of the advance slots in the plates in the dizzy.  To set for total timing you need to have a friend gently rev the car with the timing lite on until the dizzy stops advancing.  To check this have your partner rev the motor up slowly and the timing mark will move away from the zero tab.  As it moves turn the dial on the lite to bring it to zero.  Eventually the motor will advance enough till the mark will stop moving which is total timing.  Note the RPM then check the number on the dial lite to get it to zero and write it down.  That is total timing.         

Setting it is simple.  Set the dial at 34 on the lite.  Rev her up to just beyond your noted RPM.  Loosen the hold down and with the lite adjust the dizzy to hit the 0 mark.  Tighter her down, check for creep and let her idle back down and check to see what initial is at.  The difference will be the amount of mechanical advance built into the dizzy. 

Now if the car diesels, detonates, or lags the started then it has too much timing and you need to back it down. 

As I said...even lowly tired 318's will love added timing so don't be afraid to give it too her.  If done right it would be a bigger difference in idle quality and throttle acceleration.  Once the timing is reset then the settings on the carb can be tweaked and that is another post...   

[Als73charger]

I have played around with the timing(no light yet), it seems better, but still the hesitation. A friend mention something about a "ballast resistor" that was a problem with poor spark. Anyone know what he is talking about? Al

[flyinlow]

[I have played around with the timing(no light yet), it seems better, but still the hesitation. A friend mention something about a "ballast resistor" that was a problem with poor spark. Anyone know what he is talking about? Al


The ballast resistor is a wire wound resistor encased in a ceramic block normally mounted on the firewall. White color about 3 inches long with wires pluged into it at four posts if you have a stock Electronic ignition system.

If you engine starts and runs it is working normally.

The resistor and wiring allows for full battery current to the ignition coil for starting (while the ignition switch is held in the start position) and then runs a resistor limited current to the coil when the ignition swich is released to the run position. This gives you a hotter spark for starting without overheating the coil while running.


Normal trouble shooting procedure: 1.  Ignition system     .......           most likely ...  $
                                                2.  fuel system            ......          common    ... $$
                                                3.  engine mechanical systems  ...  rare          ...$$$$


Set your timing first,it will improve running across the board.

You may ,however,have a worn accellerator pump in the carb. from you original post.



                     

[flyinlow]

Bad accelerator pumps show up with sudden opening of the throttle. Hessitaion,backfire, Stalling.

To check, with a warmed up engine, remove the air cleaner. The pump linkage is on the drivers side. A rod with bends going up from the throttle shaft to a lever that operates a plunger on the top of the carb. With the engine off, move the throttle  , the pump plunger should move down. Look down the throttle bores,quickly open the throttle. You should see a squirtgun like discharge in each venturi each time you open the throttle. If no squirt or it dribbles you may have a worn pump seal.

If the pump is working you might flood the engine doing this test and you will have to crank the engine a while to get it to start.

A gummed up accelerator check valve can cause the same problem, you could try a can of Gumout in the fuel tank, sometimes it helps.

[Als73charger]

  I assume the accelerator pump is in the carb? Also, if the car sits for about an hour, it won't start up unless I prime the carb. Once it is going it will stay running. However, I still have the hesitation/stalling issue when I go to accelerate.
  To confirm, If I re-build the carb, will that solve my problems? Al

[flyinlow]

The fuel system has many parts. Not all the ones that can go bad are in the carb. Assumming you have a tank full of fresh fuel and its not leaking out of any fuel lines. Is the fuel filter clean? Replace if in doubt.
Check all the vacuum lines including the power brake booster for cracks or if collapsed. Check the intake manifold to head bolts and the carb mounting bolts for proper torque. Check PCV valve,replace if in doubt. These are simple to do and inexpensive things to do before you work on the carb.

In answer to your question ,yes ,the accelerator pump is inside  the carb.  Will a carb overhual fix all of your driveabilaty problems? No guarentee. Properly cleaned  adjusted with new gaskets and accelerator pump seals it should mix air and fuel like is supposed to. You simptoms are classic accelerator pump problems.

Do you have access to a 73 factory service manual?  There are 12 pages of information on that carb.

[Als73charger]

 Well, I re-built the carb and the car started fine. Now, I have gotten rid of the hesitation, but when I go to drive it, she stalls out.
I have played with the timing, carb screws...you name it. Maybe, I need to replace the fuel filter again...I don't know anymore I guess I know enought just to screw things up. Need to get a Manual or something. The plate down low on the front of the block with the hole in the centre(for timing), where on that should I set the timing?

[RECHRGD]

There is a filter (sock) for the fuel pickup in the tank.  If the car has been sitting foe awhile there's a good Chance thank there is some garbage in the tank.  The stuff in the tank can get stirred up while driving and clog the sock enough to shut down proper fuel flow.  I would pull the tank and clean it out and get a new sock.  Good luck,  Bob

[Als73charger]

 I was afraid it would come to this ....Al

[flyinlow]

Congrats on the carb work.  I've been screwing cars up for 40 years. Don't let it get to you.

I have a 73 Factory manual . I'm on the road now ,but can send you the 12 pages of info on your 2bbl.

Dont know exactly what you mean , it starts up and does not hesitate . However it stalls.
Fuel delivery is easy to check. Warm up the engine for a minute. The carb should now be properly filled with fuel. Engine off, disconect the fuel line from the carb.

Put a piece of rubber fuel line over the fuel line ,put the other end into an empty 2 litter bottle. Start the engine ,with it idling, it should fill the bottle in a minute or two. Dont remember the exact time spec. If it does well the tank,sock,pump and filter are OK. The engine will run on the fuel in the carb for a few minutes idling.

[Als73charger]

  Appears to be the sock in the gas tank. Pulled the tank last week and it is getting acid cleaned and re-coated. The inside of the tank had fine coating of rust everywhere and the sock was pretty much clogged up. Hopefully, I will be getting the tank back this week, just in time for the nice weather! Al

[RECHRGD]

  Appears to be the sock in the gas tank. Pulled the tank last week and it is getting acid cleaned and re-coated. The inside of the tank had fine coating of rust everywhere and the sock was pretty much clogged up. Hopefully, I will be getting the tank back this week, just in time for the nice weather! Al

  Glad you found it.  I had the same problem when I got my car running.  I ended up changing all the fuel lines too.  Hopefully yours in not as bad as mine was.   Bob

[71383bee]

  Appears to be the sock in the gas tank. Pulled the tank last week and it is getting acid cleaned and re-coated. The inside of the tank had fine coating of rust everywhere and the sock was pretty much clogged up. Hopefully, I will be getting the tank back this week, just in time for the nice weather! Al

Yep...that's what i was thinking from your last post.  part of my long list of lessons learned.  Glad you found someone to clean it...I usually just toss it and get a new one. 

[Als73charger]

  Well I have now replaced the..fuel pump, coil, distributor, rotor, ballast resistor, re-built the carb and had the gas tank cleaned out, with a 1/2 tank of gas and now it will not run
I appear to have good fuel supply(disconnected gas line from carb and turned over) Gas shoots out about a 6"-8" every second. After I put it together, I took it for a test run with poor results and found one of the clips for the Cap had come off and shredded inside of the cap. I replaced the Cap and rotor, but it just won't fire up smoothly without stalling. I am at a dead end with this project.
  I do not know if I need a new electronic module or dwell sensor or what. I did try to re gap the sensor in the cap to about 10 thou, but NOTHING. Now What???  Al

[71383bee]

VERY IMPORTANT!  Did you use a non magnetic gaper when you reset the dwell?  If not the condenser is toast. 

What is happening...

Does it turn over and not fire?
Do you have spark from the Dizzy?
Do you have spark from the coil?
Did you clean out the fuel line after changing out the tank? 
Is any old gas left in the tank/system?

[Als73charger]

-it turns over, starts and runs rough and dies right away
-I had spark from the dizzy(took plug wire from #1 and held to block)
-I did not clean out the fuel line(but I seem to have had lots of gas pumping out to carb)
- no old gas anywhere(only perhaps gas from before I removed tank for cleaning)
-It appeared that once I finally got the sensor lined up with one of the pointy things on the rotating part of the dizzy, it looked like it had been rubbing, so I gapped it by eye, so it looked like the     
thickness of a High E string of a guitar(.010)
- If the rotating part of the dizzy and sensor were rubbing together, we this be a possible issue?

[71383bee]

Okay so at least you have spark and fuel so that is good.  Having lots of gas come out is not really a good indicator that the pump is operating properly.  You need to have between 5 to 8 psi or constant pressure for the engine to run well. 

For a lot of the reasons your finding is why I recommend replacing virtually the entire fuel system and rebuilding the carb BEFORE even trying to start the car.  There still is a chance that there is buildup of garbage in your newly rebuilt carb since you boiled the tank out afterwards. 

Yes the magnetic pickup can not be touching the reluctor...there's got to be a reason it  did that to begin with tough.  You need to get your self a factory service manual pronto to help set that up.  That would be my primary suspect right now and I would just take it to a parts store and swap it for a replacement dizzy. 

Are all of the vacuum lines properly seated and in good condition?  There are no open ports on the carb or intake?  Sounds kind of like a vacuum leak too.  Keep at it..just keep it simple and fix one item at a time.  It usually is the simple stuff that gets out of whack. 

[flyinlow]

The distributor pick-up is a magnet. When you set the air gap between the pick-up and the reluctor , you want to use brass or aluminum or plastic feeler gages. Not steel or stainless steel.  Set at .006-.008 inch.  The ignition system is not normally that sensative to the exact gap. I have set them by Eyeball before and they run.

As far as the reluctor hitting the pick-up. Three things that can kill a magnet: heat it ,beat it or subject it to an AC current. However pick-up is normally pretty rugged.

[flyinlow]

You have never mentioned the spark plug condition?

Just to make sure I am on the same page as you.  You go out to a cold engine, pump the accelerator to set the choke, turn the key, the engine fires promply, then run rough for a short period of time after you have let the key return to the run position , then dies.......Sounds like a vacuum leak.

Can you keep it running by feathering the throttle until it warms up?

If the engine fires then dies as soon as you release the key to the run position you might have a bad ballast resistor. You did mention you replaced the coil,distributor and ballast resistor.