What size carb for new hemi?

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Map63Vette

Map63Vette

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So what are you carb guys out there running on your new hemis? I was looking at some of the intake/carb package deals that companies offer (like XV and Indy) and the carbs just seem kind of small to me. With the Indy Mod Man intake setup you have a choice between a 500 Edelbrock or 600 Holley if you go with a single 4 bbl, not sure exactly what the XV setup is, never saw a size for it, but I think it was around 600 or 650. Admittedly I don't know much about carb sizing, but I would think a good breathing motor like the new hemis would like a bigger carb on top since a lot of the old small blocks I've seen have been that big or bigger.
 
The carb used on the XV '420HP' package is a Holley 650 4150 vacume secondary carburator. That would be a good place to start if you are using an aftermarket cam with your 4bbl aftermarket intake and headers. A 600 may be better if you are using a stock cam and exhaust manifolds. If going with Edelbrocks dual 4bbl intake a pair of 500's would work. There is a gentleman(hemijojr) here that uses that set up on his Barracuda. he seems to be quite happy with it. He posted some pics in this thead: http://www.forabodiesonly.com/mopar/showthread.php?t=102169

I plan on using a Holley 780cfm 4150 with vaccume secondaries, an old Carter Competition AFB 750 or maybe a 750 double pumper on mine when the time comes. Just because that is what I have. But mine is a 2009 with better flowing heads and will have an Inertia cam, headers and an Indy ModMan intake.

This is all based on what I have read and seen. Hopefully somebody who has some hands on expierience will chime in and add thier 2 pennies.

Hope this helps you a little.
 
Hmm, okay, I might be able to reuse what I have on the 318 for now then, that would be nice to save some money on the initial swap. I intend to do a cam and head swap later after I get some more money built back up and figured a 600 would probably be pushing it with the big valve inertia heads and SRT Max cam, lol.
 
Most folks tend to over carb. Something in the 600 to 700 range will work well.

I have 360 and have tried 600, 670, 725 and a 750. The 670 is by far the best all around, it provides the same top end (as measured by the butt dyno) as the bigger carbs and the great throttle reponse of the 600.
 
I'm liking the looks of the Indy intake. I haven't dyno'd one, however I did do a dyno comparison using a stock 5.7 truck intake, 6.1 SRT8 intake and the XV intake. The XV showed the least amount of hp/tq of the 3 intakes we dyno'd that day.
 

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Yeah, I was a little disappointed with their dyno numbers on their site. The stock engine is supposed to make 345 hp and 370 ish ft-lbs of torque and they came up with 360 hp and around 300 ft-lbs of torque on their complete swap setup. That seems like a huge drop in torque for not really changing anything internally. I also saw some magazine article where they actually detailed the swap of a Mopar crate 5.7 into an A body, but they only came up with 250 rear wheel power. I know there are driveline loses and accessory losses that aren't necessarily considered in the engine rating, but that seemed like a huge drop off from what i would expect.
 
Just double checked what I've got on the car now and it's a Carter Competition AFB that's rated at 625 cfm. I guess the main question is whether this would fit an intake like the Indy Mod Man. It's not a wide open bore like the XV or Mopar setup, but rather the four independent holes. Not sure what flange style the Carter is though, does someone know off the top of their head?
 
It's a square bore carb. It will work on the ModMan or the XV. So will a Holley 4150.

You should call Indy and talk it all over with them before you purchase. They will have all the information you could need and supply the best answers on the ModMan. Ask them about low end torque and drivability while you are at it.
 
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