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Discussion Starter #1
I got my first big block. its a used stock 454 block and heads. it has a wiend team g intake and a bigger cam i'm not sure of the make and size cam. my question is i already have a holly 650 doble pumper will this carb work or is it to small
 

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Hey cro77, thats a good question if the cam and compression are not known.
If the car is used mostly on the street and the carb is in perfect working condition, there is a very good chance that you would be happy with it.
That carb when tuned to the engine properly will make about 400-450 HP, you mainly need to look at the driveline, weight, and use of the vehicle in addition to the mentioned cam and compression.
There is a VERY good chance that you dont need MORE carb than you have for a street engine and if it is to be used largely for weekend racing and can find out the cam specs, compression ...etc it would be easy to make a recomendation.
 

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The motor will run fine with a 2-bbl on it, but if you are going to get the most horsepower out of it, double the cubic inches to get the proper cfm.
 

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Like techinspector mentioned, it will run on most carbs from 200 to 900 cfm.
Do you want it to run or run right?
To get the right cfm and type to make you and the engine happy, all the information about the driveline and use need to be part of the calculation.
I have about 20 years of setting up and tuning street and true race carbs and about 75% of the time the owner wants to "brag" about the cfm and buys one thats too big. I have made a lot of income from selling the "too big" carbs, given to me after removing it from the engine of someone not happy with low speed performance as well as power when the wrong cfm or type was chosen.
One of Holley's top experts made the statement "we sell more 850"s than any other carb and 90% of street engines can't use a 650!
CFM is cubic feet per minute of air, the engine must cause enough air flow for the carb to draw the fuel from the main system properly in the rpm range you intend to use it. A 1000 cfm carb on a 500 cfm engine wont make power or a happy owner.
Again, the carb you have will make more power than you will likely need.
In the event that this turnes out to be a big cam and big compression engine running on performance fuel, a larger carb would be in your future.
Think about this also, a 650 without the choke,with propper linkage setup and a substack will be an honest 750 CFM. You can keep the low end performance of the 650 and tune in more power as well.
 

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Discussion Starter #5
thanks 4 the info

the 454 is going in a 68 chevelle,th350,shift kit ,3500 stall,456 reae end,this is how the car was set up when i bought it.It is mostly a street car, but i would also like to take to the track a few times a year.
 

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Traction might be the biggest problem! :thumbup:
If this carb is in good shape dial in the jets and pumps before changing to a bigger carb that will need the same.
With an automatic trans it will always be best to start with a smaller carb and move up only when you have full traction in all gears, even then you might be happy as is.
Good luck with the car.
 
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