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Carter AVS block off plate for idle compensator #3095624
11/19/22 09:53 PM
11/19/22 09:53 PM
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Northern Virginia
Moparmaniacc Offline OP
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I'm rebuilding an AVS and the artcile says I should make a block off plate for the idle compensator. Does anyone make those, thanks.

Re: Carter AVS block off plate for idle compensator [Re: Moparmaniacc] #3095627
11/19/22 10:11 PM
11/19/22 10:11 PM
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dragon slayer Offline
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What article? There is a check ball in the top, it would be easy to plug the inlet with a lead ball or thread it for a set screw.

Re: Carter AVS block off plate for idle compensator [Re: dragon slayer] #3095649
11/19/22 11:53 PM
11/19/22 11:53 PM
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Northern Virginia
Moparmaniacc Offline OP
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https://www.motortrend.com/how-to/m...eid=aac208fc-4f67-4e61-a997-dde3ec188a0b

"...Experience has taught us it's a good idea to eliminate the problem-prone idle compensator. We fashioned a block-off plate to replace the valve, eliminating the most common cause of erratic operation in later AVS carbs."

Re: Carter AVS block off plate for idle compensator [Re: Moparmaniacc] #3095652
11/20/22 12:17 AM
11/20/22 12:17 AM
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Fresno, CA
Jim_Lusk Offline
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I've never really known what that piece was for. It was not on all AVS carbs, but I have always put it back on and never had bad performance from an AVS. I'd have to go look at a carb, but my impression was that that was to release pressure from the intake on deceleration (this was just a guess).

Last edited by Jim_Lusk; 11/20/22 12:18 AM.
Re: Carter AVS block off plate for idle compensator [Re: Moparmaniacc] #3095677
11/20/22 06:48 AM
11/20/22 06:48 AM
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Sobieski Wi
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bee1971 Offline
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Simple

Make a new gasket using the original as an template

With the new gasket , DONT drill or punch out the large center hole

Re install idle compensator using your new gasket
Vacuum is now sealed off

Last edited by bee1971; 11/20/22 06:51 AM.

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Re: Carter AVS block off plate for idle compensator [Re: bee1971] #3095679
11/20/22 07:01 AM
11/20/22 07:01 AM
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bee1971 Offline
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Idle Compensator

The Idle Compensator is generally used on vehicles with air conditioning. When a vehicle comes to a stop and the engine is hot, the carburetor tends to richen up and even percolate (boil). The compensator has a bimetal piece of metal that when the temperature gets hot, the bimetal curls up and causes the idle compensator to open. This allows extra air into the intake, below the throttle valve.


1971 Dodge Charger Superbee
2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded
Siberian Huskies
Re: Carter AVS block off plate for idle compensator [Re: bee1971] #3095685
11/20/22 07:37 AM
11/20/22 07:37 AM
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SomeCarGuy Offline
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What trouble are you having? I’d not be making a change like that just because an article said to. Did it say what issue it would correct and are you having that issue?


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Re: Carter AVS block off plate for idle compensator [Re: SomeCarGuy] #3095703
11/20/22 09:33 AM
11/20/22 09:33 AM
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Apollo, PA.
B1MAXX Offline
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Temp, controlled vacuum leak. Emission related would be my guess. I have plugged them, and left them alone. Chose your direction. In apps like when I ran two on a tunnel ram I plugged them.

Re: Carter AVS block off plate for idle compensator [Re: B1MAXX] #3095734
11/20/22 11:17 AM
11/20/22 11:17 AM
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dragon slayer Offline
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Ok, As Bee71 stated hot air compensator normally for AC cars and auto, but the 70-71 hemi cars had it regardless. I have seen articles state if can reduce airflow 25cfm, but I think that is the version shaped like a T vice some like hemi which are just straight.

Removing it and you can put inverted expansion plug or piece of aluminum rod in hole.

AVS also have off idle valve which is what I thought you were talking about. It is a check ball under cap in the top. Off idle as manifold vacuum is exposed to the metering circuit it opens the ball and draws extra air to lean off idle mixture for exhaust emission control. I have seen rebuilt AVS where this gets plugged or been capped.

Re: Carter AVS block off plate for idle compensator [Re: dragon slayer] #3095788
11/20/22 02:34 PM
11/20/22 02:34 PM
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lewtot184 Offline
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if the OP can control the heat the carb is exposed to the compensator shouldn't have a major effect. of the course that's in an ideal situation and there are times when things aren't ideal. if it were me i'd just stuff a lead plug down the hole and screw the bi-metal valve back down and forget about it.

Re: Carter AVS block off plate for idle compensator [Re: lewtot184] #3095867
11/20/22 07:49 PM
11/20/22 07:49 PM
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dragon slayer Offline
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I think you're missing the point of removing an obstruction that blocks/diverts airflow through the secondary.Take it off and plug as I stated. Leaving it on plugged doesn't do much.

Re: Carter AVS block off plate for idle compensator [Re: Moparmaniacc] #3095925
11/21/22 02:43 AM
11/21/22 02:43 AM
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I've seen many magazine writers fed a line of baloney sauce by supposed "experts" testing the writers knowledge and gullibility to see if they will print bad or misinformation. Me thinks that article was one of them work twocents
I've had a bunch of 1968 to 1971 Mopars, both BB and SB that had that type of carb and never had any issue with that device, I've never block them off or heard of any other Mopar SS and Stock class racer say to do that, including John Bauman, Mopars main carb guru back in the mid 1970s shruggy I did make sure they seated properly against the main body wrench

Last edited by Cab_Burge; 11/21/22 02:44 AM.

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Re: Carter AVS block off plate for idle compensator [Re: Cab_Burge] #3095934
11/21/22 09:11 AM
11/21/22 09:11 AM
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lewtot184 Offline
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Originally Posted by Cab_Burge
I've seen many magazine writers fed a line of baloney sauce by supposed "experts" testing the writers knowledge and gullibility to see if they will print bad or misinformation. Me thinks that article was one of them work twocents
I've had a bunch of 1968 to 1971 Mopars, both BB and SB that had that type of carb and never had any issue with that device, I've never block them off or heard of any other Mopar SS and Stock class racer say to do that, including John Bauman, Mopars main carb guru back in the mid 1970s shruggy I did make sure they seated properly against the main body wrench
those "compensators" are only a problem if the carb/engine gets too hot. they're just a controlled vacuum leak to speed the engine up. real problem is they introduce air but no fuel and create a lean condition. a simple insulator carb base gasket would solve most of the issue.

Re: Carter AVS block off plate for idle compensator [Re: lewtot184] #3095991
11/21/22 11:55 AM
11/21/22 11:55 AM
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SomeCarGuy Offline
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An insulator is a must for these or really any carb for sure. I’m not seeing what benefit blocking the compensator brings to the table. It’s already blocked unless enough heat is built up to open it. I suppose it could create turbulence and decrease airflow, but who would’ve done a test to see if it was even measurable? I haven’t taken an avs apart in years or looked down in one that had that part in that time. I don’t think it overhangs the bore so still not seeing a way it would hurt flow. My car has the correct number avs and has factory ac. I’ll have to look down it and see if it has one.


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Re: Carter AVS block off plate for idle compensator [Re: lewtot184] #3095993
11/21/22 12:01 PM
11/21/22 12:01 PM
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dragon slayer Offline
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Actually they are designed to keep the engine from going rich. Overheating the carb evaporating fuel that is pulled in at idle creating an over rich condition. The compensating valve open to allow more air to mix with the fuel vapors to prevent the rich idle condition. They don't raise idle rpm.

As far as class racers, I doubt, though maybe they did, raced an Air Condition car. So I doubt they would have had an AC carb on the car. But maybe.

I did see an article about air flow restriction though. Which does make sense based on some of these valve shapes.







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