I rebuilt a good BBD and replaced my Holley 2280 with it. The car runs much better but is still not smooth. I know I need to fine tune the carb but I have a ques about the port for the vacuum reading. I've got 20" at a vacuum port at the base of the carb and I'm pretty sure this is also the same vacuum I'd get from the vacuum advance for the distributor so it seems like I should get no vacuum here until it comes off idle right?
Also this carb has a very small nipple on the middle section of the carb that I think is called the venturi vacuum port. It looks like it is a double wall brass nipple but I don't feel any vacuum from it and it is too small for any plug I have to cover it with. Any idea what this nipple is for?
I suspect my next thing to look at is the distributor and see if there is play in it or something??? The motor is fairly new rebuild 1978 block Super Six-w-fuel line mod and pertronix ignition.
Wires plugs cap & rotor are all new as well.
Any help is greatly appreciated.
Howard
Hampstead, NC

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

The venturi vac port is for an EGR plug it. Do you have a super 6 carb or a 318?

Vac port for the distributor is on the passenger side. I check idle vacuum by inserting a gauge into the choke pull off diaphram hose.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Look on page 3 of the Carter BBD operation and repair manual. There is a picture that shows the correct vacuum port to use for the distributor vacuum advance.

If you haven’t already, I’d check valve adjustment next.

Danny

My BBD looks very different from the one in the page 3 of the manual. I don't think I even have the port on mine they suggest as the vac advance port.
I ended up just using a gauge to find the port that, I hope, is the right one. At the base of the carb there are two small ports, one in the front and one in the rear-both have vac at idle. There is another one that is a larger size in the front that would appear to be from the same source however it only has vacuum off idle so I used this one.
I adjusted the carb again and it now runs better than ever but I still feel like I need to check the timing and make sure the TDC is correct-w-the timing marks. I also have a coolant issue that I posted about.
Thanks
Howard

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

Well, don't let's guess. Post some clear, sharp pics of your carburetor with the air cleaner removed, and if the carb's aluminum ID number tag is still attached to one of the screws, post the number on the tag.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'll try and get some pics on Fri. Some ways mine is different:
no additional items hang off the carb except choke pull off

the vent is inside the carb and uses a rubber seal that seasl against the inside of the carb on the left side and is open slightly by the accelerator pump arm at idle only-off idle it is up against the inside of the carb

The top has nothing on it but has a small hole next to the top for an allen wrench to fit through to adjust the metering rods.

Maybe this helps?

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

Here are some pics of the carb.
I thought the model would come out in the phot but it did not. I read on the side it is a model 2861 or so I thought but I must have this wrong. I will get the number later.
Thanks

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

The port facing the camera in your 2nd picture, with the rubber cap on it, is the vacuum advance port.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I thought this was the port however it has some vacuum at idle so I figured the one I'm using wold be better seeing as it has 0 at idle and vacuum off idle. I'll need to look more in depth at the tuning/adjustment articles.
I took out #1 plug to verify TDC and it looks real white so I suspect there is a lean condition. They have only been in for about 10 miles so should I give it more time to loose the original color? I know a rich condition would show by a few miles but didn't know if a lean running carb would.
Thanks-Howard

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

That's because the idle is incorrectly adjusted.
No. Connect the vacuum advance hose to the correct port.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

OK I'll check it again on Sun. I suppose the idle is too high and is causing the off idle circuit to pull air through this port. I adjusted the idle be ear only so I'll need to put a tack on it. The RPM in the manual states, I think 600-750 but if I recall that is in gear yes?

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

Idle is always adjusted in Neutral, never in gear.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yeah-sorry for sounding like a DA. I still have issues however. In using the Factory Service Manual and the adjustments listed here I am supposed to let the motor get completely warm and adj the curb idle screw to 500RPM and then adjust the idle mixture screw to get the highest RPM. I did this and then I adjusted the curb idle screw to 850. The manual does not have a listing for an A/C car but some of the other models in the book do list an A/C spec for 850 and 750 w/o A/C so I put it at 850. The problem is the vac advance starts to get a signal from the carb (I am on the port on the side of the carb now) and the timing moves 3-5 degrees from 7 to maybe 12 but is not a steady 7 degrees BTDC as it is when idle is 750. This little amt of timing change is actually consistent -w-the specs in the manual as far as advance at a certain RPM however I am sure the manual is not referring to idle advance/RPM relationship.
If I leave the idle at 750 and use the A/C which is a modern style scroll Sanden unit, the car idles at a low enough RPM that it is rough and I am afraid the car will stall.
I know there could be an A/C idle solenoid attached to the carb for idling up the motor when A/C is used but it would only give me the same timing issues. I really don't see an answer to this accept to live-w-an idle that causes varied timing or a motor that idles so low it feels abnormal.
Thanks-Howard

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org

500 rpm is too low. Keep in mind the FSM spec is for a 1bbl 1965 carb, not a 2bbl late-1970s carb like yours. Also remember the effect of base timing (the kind you set by loosening and rotating the distributor) on engine idle speed. You can usually advance the base timing a little to raise the idle speed and allow you to back off the idle speed adjusting screw to a point where there's no vacuum advance at idle.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Please keep in mind the FSM said to use 500 rpm only to set the idle mix screws and once they are set to bring it back to 750-I used 850 for an A/C car. Does this clarify anything? I guess I am asking what curb idle RPM is generally acceptable for a fairly stock 225? I suppose I should also ask what the expected RPM drop going from neutral to drive should be.
As for base timing I'm already at 7 BTDC. Is it OK to try for a higher RPM/Timing advance?
Thanks

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65 4-door Dart
70 Chrysler 300
2004 Cummins Ram 3500
1968 Dart GT Convertible-project
Chordomafoundation.org