Re: AFB Lobotomy
[Re: Craig J]
#3081817
09/29/22 09:04 PM
09/29/22 09:04 PM
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Joined: Sep 2018
Posts: 170 West Palm Beach, Florida
Craig J
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OP
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Joined: Sep 2018
Posts: 170
West Palm Beach, Florida
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The previous owner of my car was very optimistic in his description of the engine, so eventually I got a stockish 440 for it that has way too much piston to wall clearance, but at least it has camshaft bearings that stay in the block and doesn't leak a quart of oil every 150 miles. .
Last edited by Craig J; 09/29/22 09:05 PM.
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Re: AFB Lobotomy
[Re: Craig J]
#3081903
09/30/22 09:09 AM
09/30/22 09:09 AM
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Joined: Jan 2003
Posts: 12,327 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,327
Benton, IL.
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I like AFB carbs. I am not sure why, probably because so many people seem to hate the later Edelbrock versions, in particular the 1407 that have a terrible off idle lean spot after the transfer slot is fully exposed but the main circuit has not started flowing.
The CarterBrocks are not bad carbs, it's just that their tunes are antiquated and they are much more work to dial in than their competitors. Just like you are finding out. Can anyone answer why they have never done any updates to their circuits when their problems are so well known?
Master, again and still
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Re: AFB Lobotomy
[Re: DaveRS23]
#3082039
09/30/22 05:52 PM
09/30/22 05:52 PM
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Joined: Apr 2008
Posts: 117 Aus
hysteric
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member
Joined: Apr 2008
Posts: 117
Aus
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I like AFB carbs. I am not sure why, probably because so many people seem to hate the later Edelbrock versions, in particular the 1407 that have a terrible off idle lean spot after the transfer slot is fully exposed but the main circuit has not started flowing.
The CarterBrocks are not bad carbs, it's just that their tunes are antiquated and they are much more work to dial in than their competitors. Just like you are finding out. Can anyone answer why they have never done any updates to their circuits when their problems are so well known? The issue with the late Federal Mogul and Edelbrock 750 carbs is they use the wrong length booster in the primary. If you look at an earlier "correct" Carter 750 you will notice the booster is longer and that places the booster where it actually needs to be which is just after the minimum restriction of the venturii. I have swapped boosters and logged where they begin to flow after the transfer slot slows stops and from memory its was around 500 rpm so thats where the dreaded lean issue comes from. You can raise the float level a little to get the primary booster to flow sooner. If it were me I would make them have 4 transfer slots 2 pump shot wells and convert them to solid fuel metering. win win win.
Last edited by hysteric; 09/30/22 05:57 PM.
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Re: AFB Lobotomy
[Re: DoubleD]
#3082041
09/30/22 05:52 PM
09/30/22 05:52 PM
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Joined: Apr 2008
Posts: 117 Aus
hysteric
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member
Joined: Apr 2008
Posts: 117
Aus
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changing to adjustable air bleeds is not complicated on an AFB Yep that's how its done.
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Re: AFB Lobotomy
[Re: dragon slayer]
#3082109
09/30/22 11:14 PM
09/30/22 11:14 PM
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Joined: Sep 2018
Posts: 170 West Palm Beach, Florida
Craig J
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OP
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Posts: 170
West Palm Beach, Florida
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Those holes will disturb the airflow into the primary introducing a side shear effecting distribution, no???? It would have been interesting to see an AF ratio before and after mod. Including cylinder to cylinder on a dyno. Carter and the OEM had a lot of different strategies with the AFB. For some of the Chevy versions the anti perc tube was hidden and not exposed above the top. I am not sure.... the holes are big, but are also significantly offset from the main airflow. I suppose the hole could be covered but that was never my intention.
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Re: AFB Lobotomy
[Re: Craig J]
#3082123
10/01/22 07:23 AM
10/01/22 07:23 AM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Those holes will disturb the airflow into the primary introducing a side shear effecting distribution, no???? It would have been interesting to see an AF ratio before and after mod. Including cylinder to cylinder on a dyno. Carter and the OEM had a lot of different strategies with the AFB. For some of the Chevy versions the anti perc tube was hidden and not exposed above the top. I am not sure.... the holes are big, but are also significantly offset from the main airflow. I suppose the hole could be covered but that was never my intention. i think the real issues with the added holes is the chance of dirt getting in the air bleed. the added holes really are of no value. plugged/dirty air bleeds make the engine run poorly. the primary booster actually has two air bleeds that influence low rpm operation. there should be a small brass air bleed on the side of the booster that runs in conjunction with the one on top of the booster.
Last edited by lewtot184; 10/01/22 07:26 AM.
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