Slant carbs have a bent PCV fitting, thicker where the flat part of the choke plate is at the top. The area where the idle screws in the throttle plate are the holes are smaller. The venturi is smaller. How to tell that? I don't know.

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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

BTW when using a super six carb? Use a Super Six carb to manifold gasket. Use the 318 gasket if it is a 318 carb. There is a difference!

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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

I'm about 105% sure I don't have a super six bbd. The only thing not very 318 about it is the missing throttle plate holes, but maybe they weren't all like that. If anything it's a 76 V8 318 carb that someone maybe put a different throttle plate on or something, and thus the misalignment of the ported vacuum slot.

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1970 Plymouth Duster, 198 Slant Six, Super Six setup w/ EI conversion

http://www.semisynthetic.net/kill-9/gal ... p?album=34

Some times things go wrong at top of carb, jamed metering rods etc, that hold throttle open. Disconnect accelerator pump linkage and see if that helps. Has carb been rebushed?

I got a BBD from a slant six off of ebay today, so I'll hopefully be able to frankenstein a working carb off of the two. The throttle plates on the ebay one seem to have the correct ported vacuum setup.

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1970 Plymouth Duster, 198 Slant Six, Super Six setup w/ EI conversion

http://www.semisynthetic.net/kill-9/gal ... p?album=34

Well, not much luck today. I did have luck in that the new BBD does have proper ported vacuum, so that's good. However, even with this different carb, I still can't seem to get away from the vacuum leak, or what I think is a vacuum leak. It's like I can't tighten the carb down to the manifold tight enough. The old carb I had to tighten a couple times and the vacuum leak would seal up, and then the next time I would warm it up it would be back again. The carb nuts even have lock washers on them to help keep them tight. The nuts are tightened down so much that the wrench is slipping off and tightening them any more is extreme grunting, and I'm not weak in the arms. I tried taking off the thick flange gasket and using a thinner one, the one without the metal supporting the holes, and it acts the same. I can't get rid of the leak any more. I can't even really tell that there is a leak, with carb spray or anything. I just know that a couple times on the old carb I could tighten down the flange and it would go away until the next time. So, right now I'm stuck with a horribly idling and behaving car, which I can't really drive. I'm afraid it's leaning out from the leak.

Anyone have any other gasket recommendations, or ideas for sealing the gasket? Is using sealer a good idea on a carb flange? Would a leak develop through the carb bolts/studs somehow? I welcome any ideas. I really should be moving on to my suspension at this point, which is hard enough!

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1970 Plymouth Duster, 198 Slant Six, Super Six setup w/ EI conversion

http://www.semisynthetic.net/kill-9/gal ... p?album=34

In the carb pile,found a 318 carb with no holes in the throttle plates and egr port in base plate. The same as your carb. Vacuum advance port above plate at closed throttle. Losened the 4 screws that hold throttle plates to shaft.Moved plates very slightly off center. After this at closed throttle vacuum advance port was under plate. Just like your carb. Re ajusted plates back to center and vacuum port back above plate at closed throttle. This adjustment might help.