340 six pack carbs will this work? 440/340 combo

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J.B. said:
I can buy a brand new 4792 350 cfm from holley for center but they dont have the 500cfm 4789 amd 4790 outers. Looking at the 440 outers they are the exact same 500 cfm same body, same linkage, same style. I was told the jetting was the only difference and I can run it MrNorm did it with chevy tripower part numbers on there rare demon 340 six pack cars. Im running a hot cam .494/.513 & 268 /276 duration. Will running this setup work? I prefer to buy 3 brand new carbs then deplorable setup that need thousands more for rebuilding.
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What did you end up doing?
 
spchallenger340 said:
So just some clarification on the 500 end carbs ... I also have a 340 Six-Pack set up .. looking for some spare ends 500 carbs original parts numbers are 0-4790 rear and 0-4789 front .. found both but between the price to buy and restore is crazy.. so I purchased a new center from Holley 0-4792 350 CFM .. I see they no longer remanufacture the end 500 carbs for the 340.. so I have been looking at the 500 CFM carbs for the 440 engine 69/70 Holley 0-4365 and the 1971 440 engine 0-4672 .. I've been told the 69/70 has a different style metering plate and the 71 has the same style metering plate that my 340 end carbs have in them just a different jet size. Question will either of the 440 end carbs work on my modified 340 ? and if so should I go with the 69/70 or the 71 carbs? any help would be greatly appreciated from anyone who has dealt with this scenario. Thanks
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Read below.
spchallenger340 said:
So you’re saying the 440 base plates are different than a 340 base plate?
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No, you read into what he said and didn’t pay attention to what he said.
The metering plates, those plates are inside the carb bowl, they meter the gasoline instead of jets, are different. The best way around this is to get the ProMax or Quick Fuel metering jet plates that replace the OEM metering plates so you can use jets to fine tune the end carbs.
 
rumblefish360 said:
Read below.

No, you read into what he said and didn’t pay attention to what he said.
The metering plates, those plates are inside the carb bowl, they meter the gasoline instead of jets, are different. The best way around this is to get the ProMax or Quick Fuel metering jet plates that replace the OEM metering plates so you can use jets to fine tune the end carbs.
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Correct I'm just wanting to find out what the difference is between 340 six-pack carbs and 440 six-pack carbs and the only thing I've been able to come up with is different metering plates in the 500 end carbs and different kill bleed hole sizes SB .046 and BB .036 other than that should be the same carb?
 
They will work fine. I have had 440 carbs on my engine, tried my stock metering plates, and the Promax, the carb body is fine. Your engine will never know the difference.
 
spchallenger340 said:
Correct I'm just wanting to find out what the difference is between 340 six-pack carbs and 440 six-pack carbs and the only thing I've been able to come up with is different metering plates in the 500 end carbs and different kill bleed hole sizes SB .046 and BB .036 other than that should be the same carb?
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Yes. except the rear 340 carb has an air/fuel distribution tab on the passenger side.
 
I'm going to have to look for that tab, don't remember my carb having it. Going out now.
 
Guess this is the tab.

20240524_182547.jpg
 
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