Carb too big?? - Chevy Nova Forum
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Old 28th-March-2011, 11:23 PM   #1
Millertime

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Carb too big??

I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??
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Old 29th-March-2011, 12:09 AM   #2
levisnteeshirt

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yes it is ,,,, unless it has some serious compression , and is a full race engine ,, i would take it off


give us some details on the motor
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Old 29th-March-2011, 12:12 AM   #3
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Originally Posted by Millertime View Post
I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??
depends on what has been done to the engine.. a modified 350 can handle a 850.. what are the specs on your engine?
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Old 29th-March-2011, 11:32 AM   #4
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That's listed as a 4150. Is it vac or mech secondary?
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Old 29th-March-2011, 12:00 PM   #5
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i had a 800 dp on a mild 350 a while ,, a 600dp or a 750 vs did way better
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Old 29th-March-2011, 03:00 PM   #6
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That's listed as a 4150. Is it vac or mech secondary?
mechanical, im going to upgrade my spark plug wires and battery and see if i can get the spark to keep up with all the fuel.
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Old 29th-March-2011, 03:22 PM   #7
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smell your oil from time to time ,, make sure it doesn't start to smell like gas
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Old 29th-March-2011, 04:08 PM   #8
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It's too big. Plain and simple. I ran an 850 on a 615hp 383. On my 465 hp 355, a 750 killed an 850 in back to back comparison.
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Old 29th-March-2011, 05:09 PM   #9
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can you rejet the carb? or is my only safe option to just buy a smaller carb?
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Old 29th-March-2011, 06:57 PM   #10
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if you have a mild 350 sb i would get another carb..
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Old 29th-March-2011, 08:10 PM   #11
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Smokey Yunick Ram Intake

Smokey Yunick ram intake - Smokey said one 850 carb on a 302 is enough. I was going to run the intake on a 350 cu inch engine with an 850 cfm carb.
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Old 29th-March-2011, 08:33 PM   #12
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smokey yunicks 302's were 12.5 or more compression ,, 8000 + rpm engines ,,, ran for short periods before the oil was changed ,, things like that
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Old 29th-March-2011, 08:37 PM   #13
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Smokey Yunick ram intake - Smokey said one 850 carb on a 302 is enough. .
Enough for it and the 283 sitting next to it....

It would take a BUNCH of RPM to make that work.
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Old 29th-March-2011, 09:04 PM   #14
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IMO, 850 CFM Mechanical is WAAAAY to big for a mild 350.
If the car has auto trans, you would be much better off with maybe a 600-650 cfm Vacuum Secondary. DPs don't work well unless you have a built auto with higher stall converter.
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Old 29th-March-2011, 09:20 PM   #15
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Quote:
Originally Posted by Millertime View Post
I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??
There are alot of myths about carb cfm,there are small blocks that run 1000cfm domanators and love it,I have seen small blocks with high rise intakes with dual 600 cfms x2=1200 cfm ,while others cannot make a 600 1850 work right ,I have a 780 holley on a 355 and the engine loves it ,there are some guys who say you can make any size cfm carb work on a small block,and some that say 500cfm is all that is needed,some say the more air you can push through intake the better,who really knows? How does the car run with that carb? Is it the carb or igntion or a mech issue? The carb may or may not be right for that engine ,just saying.
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