need help with carb on my son's 72 charger

[oldrock]

My son has a 1972 charger that is his first car. We spent the summer restoring it and had it running pretty well by end of summer. Idled well but when you try to stomp on it, it would cut out. Accelerate slow and it would be ok. Car has original 318 with the stock carter 2bbl carb and the carb was leaking a little thru the side linkage which had his Mom and me concerned so we bought a rebuilt 2 bbl carb for it. Hooked up the newly rebuilt carb and no more gas leaks but now the engine is running worse!

With the vacuum hooked up, car would immediately die. I have a timing light and tried advancing and retarding timing and no luck. At best, car would idle rough and die once you put it in gear. So we blocked off vacuum and manually adjusted the timing. We have it at 18 and car will idle nice although it is a bit fast at around 850rpm. The problem is once we get the car out and drive, it bogs badly off idle. Most noticable when going up a hill. If we pump the pedal, we can get it past the bog and car accelerates on up but we really need to get problem solved since the hesitation is dangerous. Any advice? I am not really a carb tuning guy but can do the basic stuff. Should we keep tweaking the manucal timing setting or try to get the vacuum advance working? Any specific things we should try?

Oh, we have already changed fluids, plugs and wires, fuel filter. Trying to avoid just replacing parts but will if we need to. Don't want him to drive it and have an accident because it dies in traffic.

[440charger68]

okay i had the same problem with my 68 when i had the old two barrel, it was a number of problems for me though, first it was my fuel pump, it sat too long and could barely function and was not supplying enough gas to the carb. u can have a vacuum leak, i had a split in my gasket where the carb meets the manifold, and u can test the by spraying starter fluid around the carb while running and if its a vacuum leak the motor will speed up. i dont recomend doing it though after running the car too long and its hot. if u didnt clean at your gas tank there could be water in there and dirt and it will clog your jets

[oldrock]

thanks for the reply. we did change the gasket when we put the rebuilt carb in there. I will check for leaks though as new gasket doesn't necessarily mean no leaks on old cars with rebuilt parts. If it is leaking, the question would be how to fix? I know gasket sealer is the cheap and not so good fix but would it be ok?

We put a new gas tank in and flushed the lines, changed the fuel filter so don't think that is an issue but we did not change the fuel pump. Maybe we should just replace that as a preventative measure? We did disconnect the dist and crank the engine when we were changing out the fuel filter just to confirm the fuel pump was running. It did pump a strong flow of fuel although it was kinda surging. I figured that was just because the engine cranks kinda slow. Think we should replace the fuel pump anyway?

[Back N Black]

Have you adjusted the idle/fuel mixture. Check the fuel pressure before changing the pump, no need to install parts if not required. Also if you have a vaccum gauge adjust the timing to achieve max vac. There is lot of info on here WRT carb. adjustment, just do a search.


Edit: found a great link on carb and timing adjustment.

http://www.sweptline.com/tech/engine2.html

[440charger68]

yea i wouldnt replace the pump either, they all have a pulse like flow. there vary similar to those old hand pumps that pump water on the farm but its the cam doing the pumping i beleive 

[elacruze]

Since it's a serious safety issue and it's your son, I'd choose one of two paths;

Resign yourself to parking the car until you gather enough resources to learn about the carburetor, source the parts, and get it rightly sorted out, or;

Find somebody local who has a good reputation (to me that means gets paid for it) for carb tuning and have them do it, preferably while you watch over their shoulder. (which may cost extra lol)

[lisiecki1]

can you post a picture of the carburetor from the front of the car so I can verify it's the one i'm thinking it is?

[oldrock]

all good advice. I didn't have a pic of the new carb but here is a pic of the old one and the new one is just like it.

[lisiecki1]

do you have those taped off ports taped off on the new carb?

also, if I remember correctly, turn both of those mixture adjustments on the bottom front all the way in and then back them out 2-1/4 turns, then start the car and turn the passenger side in until the motor just starts to stumble and then back it out a quarter turn and then repeat on the drivers side.  Set the timing according to the FSM and connect the vacuum advance and then set idle speed.

also, is the choke working correctly?  Is it fully open at operating temperature?

[oldrock]

the rebuilt carb came with rubber covers to plug the extra vac lines so thats not it. I will do what you suggest though and see if that helps and report back. thanks alot!

[lisiecki1]

the reason I asked about the ports is because I could swear mine was connected to a different location....i'm going to go look at the FSM now....

[oldrock]

that could be it because we just hooked it up the way it was before. It had some hesitation before too just not as bad as now. If it was hooked up on the wrong port, that would also explain why the vac advance is acting wacky now. Maybe I should just do an experiment and try hooking the vac advance to the other port and see what happens.

[lisiecki1]

according to the FSM your advance should be connected here.

[oldrock]

Hey thanks a bunch for looking that up. We will go try that port tonight and see if that could be our problem. If it is, that would be awesome! I had labeled the lines so know it was hooked up to the back when we bought it but I should have assumed that didn't mean it was correct. I'll report back soon as we have a chance to reset base timing to spec and hook the vac advance to that side port. 

[oldrock]

told my son about the possible fix and he couldn't wait so we went out and tried hooking the vac advance up to the side port. Sure enough it fired up! Before the engine would not even crank with the vac hooked up so that certainly our problem. I didn't take the time to reset the timing, we will do that tomorrow after Josh gets home from school and see if we get this problem sorted out. Thanks again for looking that up for us. It might not be the only problem but it certainly was a problem so very glad to have that fixed. Would be really sweet if all we have to do is reset the base timing and it runs good. What base timing do you think we should try on the 318? And to be clear what I call base timing is the setting we do with the vac line blocked off and engine warmed up at idle. I think the car tag suggested 4 or 6 degrees btdc but the manual we had said 0 degrees.

[lisiecki1]

i would set it according to what the tag under the hood says....I can check the FSM for that tonight too

[oldrock]

Sounds like Josh needs one of those factory manuals. The generic haynes one we have stinks.

[lisiecki1]

if you ask me it's worth it's weight in gold......i lucked out about 10 years ago when my cousin was getting rid of a car he gave me the body service manual he found in the car that just happened to also be for my 73.....but the chassis manual came with the car from the previous owner.

[oldrock]

just a quick update, we have gotten tons of rain so couldn't work on the charger but today is the day. I have my carb tuning buddy coming over and we are going to get it running right today... I sure hope so anyway. If needed, I am going to break my rule of making Josh pay for the parts to fix it up and just get it running right for him. His Mom and I think safety trumps teaching him lessons about money management. Don't want him merging into traffic adn hve the charger hesitate on him, could be dangerous for a new driver.

I'll post back when I have news. We figure try adjusting first adn if we don't get results we want, we replace parts that could have influence such as fuel pump, points, rotor and cap, etc. Then if we have to, start chaging jets. 

[Back N Black]

Hey, your a cool dad for sorting his car out. 

[oldrock]

thought i would give another update on the charger. The good news is it is running again! Not perfectly but much, much better. My buddy came over and we had to do alot of work to sort out what was going on. Ended up being a number of things. One of them was just simple too lean situation. Next the vac that controls the choke that closes the butterfly on cold starts and the thermo choke were not working properly. Basically the thermo choke isn't working strong enough so the vac diaphram that opens the butterfly was overpowering the thermo that closes the choke on cold engine. Also the vac timing advance is not working properly. We still don't have that fixed (going to need a new one probably) but my buddy was able to compensate for it not working properly and got the motor running. We also were not giving enough pump shot so had to change that too to get more shot. So it wasn't one thing but alot of little things. With all the changes, we have the car running and driving pretty good but not 100% yet. It still has some hesitation between idle and power band but it is drivable again. My buddy and I think we may still have an issue with the lean situation. Might have to break down and change jets up a size or two but at least the car is back on the road. Josh was very happy to drive his charger again today and is looking forward to using it to drive to and from school.  Not cool to have the charger in the driveway and take the bus to school 

[ixelerate]

hey oldrock I have EXACTLY the same issues my 72 charger, and I did all of the regular maintenance things you mentioned in the first post.  At this point I'm most likely just going to throw on a 4 barrel with a new intake, but I will be watching this thread to see how it all works out!  I drove my 72 to high school and it felt pretty good pulling into the lot past all the ricers! 

[oldrock]

car is running better but still not correct. We have been doing alot of the regular stuff so at this point, we think problem is either timing related or jets. Seriously thinking about getting an electronic ignition with a programmable timing curve to take that all out of the equation.