Slant Six Forum :: rebuilt BBD-runs much better but still not smooth

Actually, you want the final idle mixture adjustment to be clockwise (in), otherwise the adjustment will change with engine vibration. See [url=Carburetor operation and repair manuals (and some training movies) are posted [url=http://www.slantsix.org/forum/viewtopic.php?t=33102]here[/url] for a more detailed description of how to adjust idle mixture.

EDIT: I thought of another potential problem. Maybe the spring does have friction. Maybe it hangs on the screw and twists a little, then there would be a reverse direction spinning pressure on the screw that could relieve with vibration?

Where would I find the timing idle spec for a 1978 Aspen motor?

Also does it make a change if the car is in park or neutral?

Author:	Reed [ Sun Apr 26, 2009 8:12 am ]
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Yes.Factory base timing for slant sixes varied by application from 5 ATDC to 12 BTDC. Try setting the curb idle at 750 in neutral, and bump your base timing up to 10 degrees BTDC. Start with your idle mixture screws at two turns out each, then leanthem up 1/4 turn at a time on both screws until the idle gets rough. Then back each screw out 1/2 turn.

Author:	SlantSixDan [ Sun Apr 26, 2009 9:31 am ]
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Actually, you want the final idle mixture adjustment to be clockwise (in), otherwise the adjustment will change with engine vibration. See here for a more detailed description of how to adjust idle mixture.

Author:	ppsi [ Mon Apr 27, 2009 9:41 am ]
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I do need to get deep into the manuals and videos before I can call this carb OK 100%.Where would I find the timing idle spec for a 1978 Aspen motor? Also does it make a change if the car is in park or neutral? I cannot imagine so but I've been wrong too many times to not ask the question. The final turn going in toward compressing the spring makes sense-sort of like taking up backlash on a machine tool I suppose. Thanks all-Howard Quote: Actually, you want the final idle mixture adjustment to be clockwise (in), otherwise the adjustment will change with engine vibration. See [url=Carburetor operation and repair manuals (and some training movies) are posted [url=http://www.slantsix.org/forum/viewtopic.php?t=33102]here[/url] for a more detailed description of how to adjust idle mixture.

Author:	SlantSixDan [ Mon Apr 27, 2009 2:38 pm ]
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Quote: Are you sure Dan? Yes. The end of the last coil of the idle mixture screw spring digs into the underside of the screw head and into the throttle body when you turn counterclockwise. Left under that tension, it will tend to tighten the mixture screw with vibration. No such tension results from clockwise turning of the mixture screw. Quote: EDIT: I thought of another potential problem. Maybe the spring does have friction. Maybe it hangs on the screw and twists a little, then there would be a reverse direction spinning pressure on the screw that could relieve with vibration? Exactly.

Author:	65Dodge100 [ Mon Apr 27, 2009 4:26 pm ]
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I was just making sure you understood.

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rebuilt BBD-runs much better but still not smooth https://slantsix.org/forum/viewtopic.php?t=34952	Page 2 of 2

Author:	65Dodge100 [ Mon Apr 27, 2009 12:49 pm ]
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Author:	SlantSixDan [ Mon Apr 27, 2009 7:24 pm ]
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Quote: Where would I find the timing idle spec for a 1978 Aspen motor? You're not working on a '78 Aspen, so those settings would not be too helpful. Quote: Also does it make a change if the car is in park or neutral? Not really, no. I usually use Neutral "just in case".

Author:	ppsi [ Tue Apr 28, 2009 5:50 am ]
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Sure I am-at least under the hood between the air cleaner and the exhaust pipe

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