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carb sizing help

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Old Sep 27, 2009 | 04:53 PM
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Default carb sizing help

I was given a holley 600 dp that needs a rebuild for my motor. I am wondering if it will be enough...

383

edelbrock torker 2 single plane

ported 113's with 2.00 valve

230/230 cam with .560 lift
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Old Sep 27, 2009 | 05:04 PM
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auto or manual.
normally the auto cars should get a vacuum secondary.

size should be fine.
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Old Sep 27, 2009 | 05:49 PM
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manual 3.07. It's a lightened c4 weighing about 3000lbs
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Old Sep 27, 2009 | 06:05 PM
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what is the list # on the air horn?
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Old Sep 27, 2009 | 06:12 PM
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General rule of thumb is:

(max RPM's x Cubic Inches) / 3480 = cfm

For your application:

(6000 x 383) / 3480 = 660 cfm

Would not go smaller than 650 cfm carb
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Old Sep 27, 2009 | 06:13 PM
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list-4776-2
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Old Sep 27, 2009 | 06:14 PM
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Originally Posted by hdpete98
General rule of thumb is:

(max RPM's x Cubic Inches) / 3480 = cfm

For your application:

(6000 x 383) / 3480 = 660 cfm

Would not go smaller than 650 cfm carb

I forgot, always vacumn secondaries with an auto trans.
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Old Sep 27, 2009 | 06:15 PM
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I was hoping because its a mechanical secondary that I could get away with it for atleast the break in, but if its too small, it's too small.

I was also hoping because it was free
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Old Sep 27, 2009 | 06:20 PM
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I just put a 2-plane edelbrock and a holley 650cfm, with vacumn secondaries on my 71 350/auto with a mild cam, no headers. this carb works great but it doesn't have much left at wot. With your 383/auto, I don't think you would be very happy with the the 600. By the time you have it rebuilt the difference in cost would be well worth it. I would look at a 750 but nothing smaller than 650 cfm.

Good luck.

Last edited by hdpete98; Sep 30, 2009 at 08:26 PM.
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Old Sep 27, 2009 | 06:22 PM
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its not an auto
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Old Sep 27, 2009 | 06:32 PM
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size looks very good! with a single plane all 8 cyl use the entire carb.
Most guys use a dual plane, each half of the carb feeds 4 cyl, then it is iffy.
if u put a kit in it yourself, try it!
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Old Sep 27, 2009 | 06:33 PM
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I haven't opened the kit yet which is why I am debating
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Old Sep 27, 2009 | 06:56 PM
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Originally Posted by ekess744
I haven't opened the kit yet which is why I am debating
take the bowls off, etc., is it clean or full of dried gas? if it looks ok, get a spray can of carb cleaner and blow thru every passage.
If for some reason u decide to sell it, it will fetch much more rebuilt, like 75-$100
I don't think it is the best carb, but it could run a lot better than many, so the price is right, try it!
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Old Sep 27, 2009 | 07:13 PM
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Originally Posted by ekess744
I was hoping because its a mechanical secondary that I could get away with it for atleast the break in, but if its too small, it's too small.

I was also hoping because it was free
It will work w/ your single plane intake.


AFR put a 600 DP on a dual plane 383. You can get a larger carb later.
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Old Sep 27, 2009 | 08:22 PM
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Hummm............
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Old Sep 27, 2009 | 08:42 PM
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Originally Posted by hdpete98
General rule of thumb is:

(max RPM's x Cubic Inches) / 3480 = cfm

For your application:

(6000 x 383) / 3480 = 660 cfm

Would not go smaller than 650 cfm carb
Trying to put this in a nice way but every time I see that formula I cringe. Would you use a the same size carb on a 300HP 383ci that you would use on a 550HP 383ci. ?

Seriously not trying to start anything or make anyone feel bad but that formula comes up all the time ( whatever math class it came from ) and it just makes me feel I have to say something to clear thngs up. Putting anything smaller than 750cfm (Holley square bore type ) on healthy 383ci is nonsense.

The 650cfm is good for a slightly warmed over 355ci although I had a Holley 750DP mechanical secondaries on my warmed over 355ci which made ~300RWHP and 330RWT and had very nice street manners with a single plane Vr Jr intake manifold and solid fllat tappet cam
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Old Sep 27, 2009 | 09:42 PM
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Originally Posted by MotorHead
Trying to put this in a nice way but every time I see that formula I cringe. Would you use a the same size carb on a 300HP 383ci that you would use on a 550HP 383ci. ?

Seriously not trying to start anything or make anyone feel bad but that formula comes up all the time ( whatever math class it came from ) and it just makes me feel I have to say something to clear thngs up. Putting anything smaller than 750cfm (Holley square bore type ) on healthy 383ci is nonsense.

The 650cfm is good for a slightly warmed over 355ci although I had a Holley 750DP mechanical secondaries on my warmed over 355ci which made ~300RWHP and 330RWT and had very nice street manners with a single plane Vr Jr intake manifold and solid fllat tappet cam
especially about that dumb azz formula on any kind of performance engine jmo
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Old Sep 28, 2009 | 12:15 AM
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I decided to buy a Holley 750 vacuum secondary carb. 3310 with electric choke
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Old Sep 28, 2009 | 05:59 AM
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Originally Posted by hdpete98
General rule of thumb is:

(max RPM's x Cubic Inches) / 3480 = cfm

For your application:

(6000 x 383) / 3480 = 660 cfm

Would not go smaller than 650 cfm carb
you are assuming 100% efficiency from this forumla.
no NA engine will give that. maybe close but not quite.

if it is a well tuned, efficient, large valve engine that say was giving 90% of what it was capable of the 600 would be perfect

660*.9=594cfm

if you already have the carb and it is a manual. go for it.
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Old Sep 28, 2009 | 06:51 AM
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Originally Posted by ekess744
I decided to buy a Holley 750 vacuum secondary carb. 3310 with electric choke
that is not a step up imo. i'd sell that ASAP. But,that's me; others love VS.
the 113's are ported to what? they are only 163 cc stock. about the worst head for a 383. flowing 600cfm at 1.5 is unlikely, more like 550.
a 600 DP will flow 780 cfm at 3" of vacuum.
i'd rather have the 600 DP any day on this combo

Last edited by Matt Gruber; Sep 28, 2009 at 07:18 AM.
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