What size carb ?

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bobscuda67

bobscuda67

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Hey guys I need some input. I have a 340\373 motor in my 67 barracuda. It will be street driven with a 904 auto and a 3.23 rear end. Dual plane intake and exhaust manifolds. Hughes 558 lift and 219 dur, at .050, 2600 converter, magnum heads with 9.5 comp. Shift points are 5800. What size carb should I run, and will the stock 5\16 fuel line and pump be enough. Thanks, Bob
 
depends on what you want to do really with this car..

for creditable street strip use i would think a 600cfm would be sufficient

but theres guys here that would know exactly what you should use for what your gunna need.. lets hear what they think..
 
The formula for figuring out the carb size needed for your motor and RPM is this.
6000rpm X 373cid /3456 X0.85=carb size needed for street use.
6000x373=2238000 /3456=647.569 x 0.85% street factor or V.E.=550.434streetCFM
A 600 vacumn secondary carb would work great,or a 650cfm.
Any one that would like to argu the facts can kindly go to Holley web site or any other carb site and will find this formula,so since they might know more that all of us put together,we will take it that its a good formula,Mrmopartech
 
Hello Bob, you didn`t waste any time getting that 340 put in! Just wanted to say thanks for everything and I hope all is well with you and your family.- John
 
I agree. 650 cfm. A 373 cid engine is large, but the cam is tame, comp. ratio is easy, Magnum heas do well in stock form. This should be a nice engine and pull well.
 
Are you sure you have given the right lift and duration @50 figures? 558 seems mighty big for 219 - even for hughes?
 
The Hughes part number is HEH 1928 AL. The lift is 558 IN. 522 EX. and 219 IN , 228 EX. degrees at .050. Do you think the fuel line and fuel pump will keep up with a 650 carb under full throttle? Thanks for your input.
 
yeah i got stock fuel lines and im going to run a stock style pump but i am planning to run a 750 hp series holley i would also like to know if my fuel system will keep up with the carb i had no doubt but now i am second guessing
 
I ran a stock 5/16 fuel line with a Carter street hi flow fuel pump on a 10.-1 360 w/ a TorkerII, 750, 244 @ .050 cam and Super Comp headers. Rear is a 4.10 and a 4spd Manual tranny.
It feed it.
 
Rumblefish360
Did you have an external fuel pressure guage that you could see what the pressure was at the strip? Was it the original routed 5/16 line with the ±9 -90* bends in it? Did you still have the original 5/16 size pickup w/sock in the fuel tank?
 
388dart said:
Rumblefish360
Did you have an external fuel pressure guage that you could see what the pressure was at the strip? Was it the original routed 5/16 line with the ±9 -90* bends in it? Did you still have the original 5/16 size pickup w/sock in the fuel tank?
Click to expand...
I picked up a Summitt racing adjustable regulator (Rebuilt Holley) but never adjusted anything on it. The guage, a summitt racing part was bolted to the AFB directly to the carb. I only reved the engine in the driveway to see how high it would go. It never crested 7 psi IIRC. I could have used the MoPar unit or equal to see whats going on from the seat.
The pick up was stock, w sock and 5/16 and so was the line up to the pump. After the pump it was 3/8's.

Current set up, I upgraded the pick up and lines to 3/8. I did this when I got the create short block and RPM heads and intake.
(248 @ .050 cam and zero deck piston on the RPM heads 63cc chamber and .039 gaskets.)
 
Yes, my fuel system is stock with 5\16 pickup, all the 90's in the fuel line and a stock carter mech. pump. Stock 5\16 to the carb and no fuel regulator. Weren't the 340 cars all 5\16 fuel systems? I wonder what point they would run out of fuel in a dragrace situation? I had a 69 roadrunner with a healty 383 that started to run out of fuel at topend when it was going 12.90's. I would think my stock system can keep up with a smaller motor. Bob
 
I wonder what point they would run out of fuel in a dragrace situation? Right about the time my brothers 70 383 Cornet would start gaining and pass me in my 69-340 Swinger.
At least change the fuel line from the pickup to the pump to a 3/8" relatively straight non-90*. that will help substantially - change the picjup to 3/8" when you can.
 
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