So, my slant-to-super six conversion is done and, wouldn't you know it, things are not the way they should be. Major blow-by (because of the rings, I'm sure...the added compression is making for quite a smokey run), but the biggest problem is the Holley 2280. It is the one off of Ebay that a few guys on here have purchased. NOS, but it must have some internal differences because unless the fuel mixture adjustment is way out (3 1/2 to 4 turns), she falls on her face in gear. My mechanic (all he does is build engines....for 30 years!) said that the fuel mixture screw should be 1, maybe two turns out. He said this thing is needing almost 4. He says it must be compensating for something. Any ideas oh Slant Six experts?

I suspect a vacuum leak.

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Joshua

That's the first thing he thought, but he checked and the vacuum is strong. I told him that this carb was super-six specific; that it was either this one or the Carter that went on the supers. He said that may be true, but there are differences even among Holleys with the same number. He thinks there might be internal differences that this one is trying to compensate for on the 6cyl as opposed to an 8.

Was the cam the same in a basic slant six as in a super-six? I am thinking if I go with a slightly bigger cam, the carb might do better.

No, that's not it. It's possible the carb is faulty or there may be some dirt in a passage, even though it's new, but the carb is not "trying to compensate" for being on a 6 rather than an 8 cylinder engine. Vacuum leak, improper cam and/or ignition timing, improper and/or faulty PCV valve, improper carb-to-manifold gasket, leaking EGR valve...there are lots of potential causes for what you describe.

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

Yes.
No.

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

check out my posting 'holley 2280 bowl vent',,got some photos there,, what list number did you purchase? mine is a 8431,,,,,,I think the NOS carb I purchased has internal parts missing,, I contacted the holley tech center,,
they were confused too,, they got me in contact with a re-manufacturer of vintage holley's, I spoke with them today, he asked for photos and they are sent.

The lack of an external bowl vent is not causing this problem.

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

my statements have something,, but actually, little to do with carb bowl venting, my questions has much more to do with components internal to the carburator. I expected the door / lever for for the vent to not be present,, was not expecting to also find the mechanical power valve assembly and adjusting screw missing

matt68's questions has a lot to do with motor running / performance, I agree,,not a bowl venting issue.

If power brake equipped, check for vacuum leak there as well.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC