Holley 470 cfm.
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Laughing Gas
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Holley 470 cfm.
I have a spare Holley 470 truck avenger carb that I had on other my pickup with a ford 300 six. Was wondering if the 470 would be okay for the truck originally was swap the original Motorcraft/holley with a Eddy 500 cfm but I have that on the f150 its seems to like that carb so it's staying there.
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From: Angier, NC
Ok what are you saying?
The 300 six came with a Motorcraft/Holley (size?), you pulled that off to put on the 470, you pulled that off to put on the Eddy 500 cfm carb.
Then it looks like you are talking of a different truck? and then a different carb and could it have a different motor?
I don't have a clue what you are trying to ask here.
Repost your question so we can under stand it.
Dave ----
The 300 six came with a Motorcraft/Holley (size?), you pulled that off to put on the 470, you pulled that off to put on the Eddy 500 cfm carb.
Then it looks like you are talking of a different truck? and then a different carb and could it have a different motor?
I don't have a clue what you are trying to ask here.
Repost your question so we can under stand it.
Dave ----
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Laughing Gas
Joined: Dec 2010
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Sorry no offense taken. I use the mobile app and I get used to typing like if I am texting without using punctuation. I have two 86 ford trucks one f150 (300 i6), and one f250 (351w ho). I was asking if the 470 would be okay to use on the 351w I wouldn't want it to be too small of a carburetor for the truck that's all.
Happy Sunday.
Happy Sunday.
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Joined: Feb 2013
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From: Roseville, MN
Doing the math, a 351 in^3 engine pulls 351 in^3 of air through every 2 revolutions at WOT. That's 175.5 in^3 / rev, or 0.102 ft^3 / rev.
470 cfm (ft^3 / min) / 0.102 ft^3 / rev = 4627 rev / min
So a 470 cfm carb will be maxed out at 4627 rpm on a 351 cubic inch engine. Seems a little small, but not completely ridiculous.
470 cfm (ft^3 / min) / 0.102 ft^3 / rev = 4627 rev / min
So a 470 cfm carb will be maxed out at 4627 rpm on a 351 cubic inch engine. Seems a little small, but not completely ridiculous.
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From: Angier, NC
Much better!
I would give it a try if the carb on the 351 was acting up.
Even if not you may find running the smaller 470 over the Eddy 500 will perform better.
I would have thought the 470 would be too big for the 300 unless it had a lot of work (read big cam & high RPM) as most run 390 CFM carbs on six cyl.
Different manf. have different ways to measure CFM and even ways to "round up" cfm for people that think bigger is better.
Both carbs may flow the same CFM but because of primary size & shapes one may work better than the other. Same goes for air bleed size and how it works.
Dave ----
I would give it a try if the carb on the 351 was acting up.
Even if not you may find running the smaller 470 over the Eddy 500 will perform better.
I would have thought the 470 would be too big for the 300 unless it had a lot of work (read big cam & high RPM) as most run 390 CFM carbs on six cyl.
Different manf. have different ways to measure CFM and even ways to "round up" cfm for people that think bigger is better.
Both carbs may flow the same CFM but because of primary size & shapes one may work better than the other. Same goes for air bleed size and how it works.
Dave ----
FTE Legend
Joined: Nov 2015
Posts: 30,906
Likes: 4,122
From: Angier, NC
Doing the math, a 351 in^3 engine pulls 351 in^3 of air through every 2 revolutions at WOT. That's 175.5 in^3 / rev, or 0.102 ft^3 / rev.
470 cfm (ft^3 / min) / 0.102 ft^3 / rev = 4627 rev / min
So a 470 cfm carb will be maxed out at 4627 rpm on a 351 cubic inch engine. Seems a little small, but not completely ridiculous.
470 cfm (ft^3 / min) / 0.102 ft^3 / rev = 4627 rev / min
So a 470 cfm carb will be maxed out at 4627 rpm on a 351 cubic inch engine. Seems a little small, but not completely ridiculous.
A little smaller carb will give better throttle responds and do better on MPG as it will atomize the fuel better.
Dave ----
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Posting Guru
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From: Northeast Ohio USA
Up to 550 CFM would be considered within breathing specs. for a small block Ford. Most 351W engines were produced with either the 2150 or the 4100, both of which were well below 5500 CFM.
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From: Roseville, MN
Rarely. But when you do want full power, what rpm do you want the engine to choke out at? 4600 rpm isn't too bad, but then again the math assumes everything is perfectly efficient, so it'll actually run out of breath a little earlier than that. I'm not sure a carb that runs out of breath under 4500 rpm is ideal, but it's not horrible either.
Does that mean you should put a 1000 CFM carb on a 351 to make sure it doesn't choke out until 9800 rpm? Of course not. As you point out later in your post, that would give horrible performance in typical use.
But I stand by my original conclusion, a 470 carb seems a little small for a 351, but not ridiculously so.
Does that mean you should put a 1000 CFM carb on a 351 to make sure it doesn't choke out until 9800 rpm? Of course not. As you point out later in your post, that would give horrible performance in typical use.
But I stand by my original conclusion, a 470 carb seems a little small for a 351, but not ridiculously so.
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From: Northeast Ohio USA
Exactly
Process is what is ingested at the proper rate of digestion, in order to exhaust it.... Intake, digestion, distribution, exhaust. It's physics. Would You dump a 6 gallon bucket of fuel into a 5 gallon bucket in the hope that it would hold it? No, You wouldn't.
Posting Guru
Joined: Jul 2015
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From: Northeast Ohio USA
Yep!
My point, with prominence....Thanks
