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post #1 of (permalink) Old 08-30-2003, 01:02 PM Thread Starter
 
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Carb shoppin\' - How many cfm\'s ??

The search wasnt' immediatly useful on this one, so I'll break down & post ... you'll forgive me if this has been recently discussed - lately, I've only had time to scan the post titles & read a very few. [img]images/graemlins/mad.gif[/img]

Nevermind the why's & wherefore's ... I've decided it's time for a new carb & you ain't gonna talk me out of it [img]images/graemlins/wink.gif[/img] !!

Here's the parameters for today's class discussion: We're feeding an '85 (h.o.) 351w, with msd ingintion & weiand stealth intake. Headers are a probability, though not yet purchased, but for today's discussion we'll assume headers are also installed.

I've heard all the brand discussions before, so that doesn't need to enter into it, I would like to know - simply, how many cfm's are too many (or too few) to feed this v-8 ???

Thank you for your time & attention, the best answer will recieve a free hall pass for a quick smoke in the restroom!
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post #2 of (permalink) Old 08-30-2003, 10:51 PM
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Re: Carb shoppin\' - How many cfm\'s ??

hey you know you could swap it to fuel injection, right? [img]images/graemlins/chairfall.gif[/img]

i dunno anything about carbs except that i prefer EFI... no help here just a useless post [img]images/graemlins/smirk.gif[/img]
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post #3 of (permalink) Old 08-30-2003, 11:46 PM
 
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Re: Carb shoppin\' - How many cfm\'s ??

It's a 351W, nothing special, just a niced sized small block, no high revs, no serious mods. to go with dat, ya gotta have da fries...650 CFM is more than enough. of course, for off road use, the carb you buy will have a huge impact on performance, but like you said, you have all the scoop on dat. You could even go a bit smaller.

This coming from an EFI guy. [img]images/graemlins/grin.gif[/img]
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post #4 of (permalink) Old 08-31-2003, 11:05 PM
 
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Re: Carb shoppin\' - How many cfm\'s ??

By the numbers a 302 running no more than 6k rpm will need only a 390 cfm carb. A 6-650 will feed it all day, running flat. on a hill well ask Norm......
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post #5 of (permalink) Old 09-01-2003, 02:47 PM
 
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Re: Carb shoppin\' - How many cfm\'s ??

I'm surprised more carb guys have not posted on this yet. You're right Havack in that the main thing you want to avoid is overcarbing. I mentioned 650 because it is about the biggest carb that you normally see mentioned for 350 chebbies/351 Fords. some guys build these motors and think they then need to go looking for 700+ CFM double pumpers and what not. They end up with sad performance and poor economy. I'm not sure what all is offered out there, but likely a 500-650 CFM carb will do just fine.
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post #6 of (permalink) Old 09-02-2003, 04:11 PM
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Re: Carb shoppin\' - How many cfm\'s ??

Here's Holley's carb selection guide.
As mentioned previously, 600-650cfm is recommended.

Another useful link...Air Flow (Auto Math Calculations), but I haven't used it since they recently added the "log-in" feature. [img]images/graemlins/frown.gif[/img]

<font color="blue">TheJuice</font color>:
I'm surprised more carb guys have not posted on this yet.
Hey. It was Labor Day Weekend! [img]images/graemlins/grin.gif[/img]
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post #7 of (permalink) Old 09-04-2003, 06:27 AM
 
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Re: Carb shoppin\' - How many cfm\'s ??

</font><blockquote><font class="small">In reply to:</font><hr />
on a hill well ask Norm......

[/ QUOTE ] chug, sputter, sputter, sputter, poot! [img]images/graemlins/cussing.gif[/img] Not again! Always remember, never go up anything that you would be afraid to go down backwards without power. [img]images/graemlins/grin.gif[/img] But since it's you high tech I'm guessing that it's for your race truck. An Eddelbrock/ Carter AFB with the offroad springs would do the trick for racing nicely IMO. I wouldn't go above 650 cfm either unless you got some bithchen heads on there. If you have some real breathers then it would be safe to go up to 750 so long as you got an aggressive cam as well. I had a friend that ran a 750 AFB on his windsor with the Cleavland head conversion. That was on a high revin' mustang though.
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post #8 of (permalink) Old 09-05-2003, 06:49 AM Thread Starter
 
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Re: Carb shoppin\' - How many cfm\'s ??

LOL - "Race" Truck ... but I do like the way you think, Norm - </font><blockquote><font class="small">In reply to:</font><hr />
An Eddelbrock/ Carter AFB with the offroad springs would do the trick for racing nicely IMO.

[/ QUOTE ]

The Edelbrock Thunder Series, w/ offroad needles &amp; seats, arrived from Jegs yesterday ... woohoo!! 650cfm as suggested - thanks all!
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post #9 of (permalink) Old 09-05-2003, 03:16 PM
 
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Re: Carb shoppin\' - How many cfm\'s ??

Ok good deal. Don't end your post though. You owe us feedback on likes/dislikes, etc. once you get her all bolted up and dialed in.
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