2 to 4 barrel carb swap help

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Cribbs74

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Please excise any ignorance on my part, I am new to 71-73 Mustangs. That said I am going through my 72 and I need to either rebuild the stock 2 barrel or install the 289 performer intake that came with the car. If I decide to do the latter I want to stay with an original style carb. I believe the 4300 series carbs are what I should be looking for, but I have also heard the the 4100 series carbs are good as well. I guess what I am asking is what carb would be stock replacement carb for my car? It’s a 72 coupe with a 302 2V. I see 4100 and 4300 carbs all over Ebay however I don’t know which one to look for, what the tag should say etc. I don’t want to get the wrong CFM or have to play a lot with jetting.

any help would be well…. Helpful!

 Thanks 

Ron

 

Hemikiller

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The only "non-Boss" 302 engine equipped with a 4 barrel was the one year only G-code in 1968, which used an Autolite 4300. As a rule, I don't recommend anyone use a 4300 for anything other than originality purposes. The Autolite 2100 is an excellent carb and incredibly simple to rebuild. 

For an aftermarket carb on a stock 302, I'd recommend a Summit 500cfm unit. You could also use Edelbrock or Holley in the 500-600 cfm range. You will have to modify fuel lines, choke setup and add a couple accessory brackets to make it all work. 

https://www.summitracing.com/parts/sum-m08500vs

 
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c9zx

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+1 on Hemikiller's post carb suggestions, The summit carb is basically an improved version of the Autolite 4100. The Summit carb has more adjustability and availability of calibration parts. I think Hemikiller meant J code for 1968 302 4V. Chuck

 

Cribbs74

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Ok, now I am even more confused, did you mean 4100 Hemikiller? I already have a 2100 The summit Carb may be the way to go, but this is a budget build with my son so a carb rebuild would be good as well as saving a few $ 
 

Chuck, 

Our discussion on Saturday is what got me thinking about all  this. My real concern is what 4100 is what? I have no idea what the tags decode to and also I don’t see any vacuum pickoffs on the 4100. I looked for a bit last night about 4100 info, but didn’t see anything concerning application or CFM decoding. 
 

Ron

 

Galucha

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Ok, now I am even more confused, did you mean 4100 Hemikiller? I already have a 2100 The summit Carb may be the way to go, but this is a budget build with my son so a carb rebuild would be good as well as saving a few $ 
 

Chuck, 

Our discussion on Saturday is what got me thinking about all  this. My real concern is what 4100 is what? I have no idea what the tags decode to and also I don’t see any vacuum pickoffs on the 4100. I looked for a bit last night about 4100 info, but didn’t see anything concerning application or CFM decoding. 
 

Ron
If you're gonna go the route of rebuilding a 4100, the carb CFM is based on the venturi size, which is stamped on the side of the carb. Here's a handy chart for decoding what each venturi size translates to. As far as I know, 1.08 is the most common size.

104 (1).jpg

 

Hemikiller

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+1 on Hemikiller's post carb suggestions, The summit carb is basically an improved version of the Autolite 4100. The Summit carb has more adjustability and availability of calibration parts. I think Hemikiller meant J code for 1968 302 4V. Chuck
Yes, J-code.. Hadn't had enough coffee... ;)

Ok, now I am even more confused, did you mean 4100 Hemikiller? I already have a 2100 The summit Carb may be the way to go, but this is a budget build with my son so a carb rebuild would be good as well as saving a few $ 
You had mentioned rebuilding the original 2 barrel, which would be an Autolite 2100. The Autolite 4100 is a very good carb and also easy to rebuild, so is a nice option if you can get a good core. 

 

Cribbs74

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Thanks to the both of you. I understand now HK

I appreciate the chart Galucha! Just what I needed. I also answered my own question concerning the vacuum pickoffs. They all run off of the manifold…. See, told you I was new to these Mustangs.
 

 

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