327/300 carb CFM

Mark Yacavone · 05-03-2013, 01:11 AM

Anybody know the CFM rating on that (AFB) carb ?

SStockDart · 05-03-2013, 02:04 AM

Mark, I am 99% sure it is 575 CFM....I was planning on putting a 300 HP in this Nova for SS/IA when finances (and too many cars) got in my way....LOL

Chuck Norton · 05-03-2013, 10:53 AM

Mark,

I was never sure of the rated CFM but it never seemed to be able to produce the extra 50 horsepower on the 327 that the General assigned it. On the other hand, if the 300 horsepower manifold had never been cast, where would the 283 cars have ever found that last 50?

c

Billy Nees · 05-03-2013, 11:13 AM

Quote:

Originally Posted by Chuck Norton

Mark, On the other hand, if the 300 horsepower manifold had never been cast, where would the 283 cars have ever found that last 50?

Something else that should be "fixed".

Mark Yacavone · 05-03-2013, 11:57 AM

Thanks...So it's 15 hp in a 65 Chevelle as of now ... roughly 180 lbs in J/SA over a 4GC..
I don't see it carrying that difference...Of course, without a dyno sheet.....???

Aubrey N Bruneau · 05-03-2013, 03:01 PM

Yes, I believe it IS 575 CFM. EXACTLY the same measurements as the dual 4 barrel carbs on a 409.

Greg Reimer 7376 · 05-05-2013, 09:48 PM

That carb wasn't the only difference between the 62-65 250 and 300 horse 327. A good question was brought up, but I'd like to know what the CFM rating of the 4 Jet carb that the 220 and 250 horse small blocks was. The intake difference was notable, and the 461 head as opposed to the 520 head was another factor. Is the factored horsepower really that great a difference?

Aubrey N Bruneau · 05-05-2013, 09:56 PM

and to that, Greg, part of the horsepower difference was in the upgrade to the 2 1/2" outlet exhaust manifolds on the 300 + up horsepower engines.. With headers on the engines, the performance difference was not as dramatic.
I believe the little 4GC ( 4 jet ) was around 450-475.

Mark Yacavone · 05-05-2013, 10:35 PM

520 heads on 327 /250's was 64 and earlier.
65 327...Same exact specs except for carb.
My question has to do with how much real dyno hp and whether the AFB is worth the hp to offset the weight.

I had a friend who bought a 65 Impala, 4 speed ,327/250 new, and it came with single exhaust .
I doubt you would have seen a 327/300 that way...Ancient history though.
We're living in the Now !

Greg Reimer 7376 · 05-05-2013, 10:37 PM

Seems to me a 62-64 327 300 used the same 2 1/2' exhaust head pipe as the 409 340,380 and 409 horse engine. I didn't consider that because,like you said, discarding the stock exhaust for a pair of headers negated any differences in the OEM exhausts. The NHRA factored horsepower was 250 horse for the 62-64 327/250, and 265 for the 62-65 327 300 horse engine. Someone should give it a try! Imagine a 327 265 in a Nova.Might be fun, especially with a 3 speed automatic.Interestingly enough,the 65 250 horse had either a WCFB or a 4 jet with 461 heads. Horsepower rating was the same as the earlier engine with the 520's.

05-03-2013, 01:11 AM	#1
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,806 Likes: 2,893 Liked 5,105 Times in 1,946 Posts	327/300 carb CFM Anybody know the CFM rating on that (AFB) carb ? __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

05-03-2013, 02:04 AM	#2
SStockDart VIP Member Join Date: Dec 2007 Location: Arizona, Texan forever Posts: 1,176 Likes: 876 Liked 574 Times in 212 Posts	Re: 327/300 carb CFM Mark, I am 99% sure it is 575 CFM....I was planning on putting a 300 HP in this Nova for SS/IA when finances (and too many cars) got in my way....LOL __________________ Gary Hansen - SS/FA 4911, B/SA 4911 Last edited by SStockDart; 11-18-2015 at 07:22 PM.

05-03-2013, 10:53 AM	#3
Chuck Norton Member Join Date: Dec 2001 Location: Covina, CA Posts: 472 Likes: 99 Liked 76 Times in 17 Posts	Re: 327/300 carb CFM Mark, I was never sure of the rated CFM but it never seemed to be able to produce the extra 50 horsepower on the 327 that the General assigned it. On the other hand, if the 300 horsepower manifold had never been cast, where would the 283 cars have ever found that last 50? c __________________ Chuck Norton

05-03-2013, 11:57 AM	#5
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,806 Likes: 2,893 Liked 5,105 Times in 1,946 Posts	Re: 327/300 carb CFM Thanks...So it's 15 hp in a 65 Chevelle as of now ... roughly 180 lbs in J/SA over a 4GC.. I don't see it carrying that difference...Of course, without a dyno sheet.....??? __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

05-03-2013, 03:01 PM	#6
Aubrey N Bruneau Member Join Date: Sep 2003 Location: South Eastern Alberta, Canada Posts: 311 Likes: 6 Liked 7 Times in 3 Posts	Re: 327/300 carb CFM Yes, I believe it IS 575 CFM. EXACTLY the same measurements as the dual 4 barrel carbs on a 409. __________________ Aubrey N Bruneau 6409 C/S 62 BelAir sport coupe, 409 HP 409

05-05-2013, 09:48 PM	#7
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,133 Likes: 172 Liked 703 Times in 217 Posts	Re: 327/300 carb CFM That carb wasn't the only difference between the 62-65 250 and 300 horse 327. A good question was brought up, but I'd like to know what the CFM rating of the 4 Jet carb that the 220 and 250 horse small blocks was. The intake difference was notable, and the 461 head as opposed to the 520 head was another factor. Is the factored horsepower really that great a difference?

05-05-2013, 09:56 PM	#8
Aubrey N Bruneau Member Join Date: Sep 2003 Location: South Eastern Alberta, Canada Posts: 311 Likes: 6 Liked 7 Times in 3 Posts	Re: 327/300 carb CFM and to that, Greg, part of the horsepower difference was in the upgrade to the 2 1/2" outlet exhaust manifolds on the 300 + up horsepower engines.. With headers on the engines, the performance difference was not as dramatic. I believe the little 4GC ( 4 jet ) was around 450-475. __________________ Aubrey N Bruneau 6409 C/S 62 BelAir sport coupe, 409 HP 409

05-05-2013, 10:35 PM	#9
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,806 Likes: 2,893 Liked 5,105 Times in 1,946 Posts	Re: 327/300 carb CFM 520 heads on 327 /250's was 64 and earlier. 65 327...Same exact specs except for carb. My question has to do with how much real dyno hp and whether the AFB is worth the hp to offset the weight. I had a friend who bought a 65 Impala, 4 speed ,327/250 new, and it came with single exhaust . I doubt you would have seen a 327/300 that way...Ancient history though. We're living in the Now ! __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

05-05-2013, 10:37 PM	#10
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,133 Likes: 172 Liked 703 Times in 217 Posts	Re: 327/300 carb CFM Seems to me a 62-64 327 300 used the same 2 1/2' exhaust head pipe as the 409 340,380 and 409 horse engine. I didn't consider that because,like you said, discarding the stock exhaust for a pair of headers negated any differences in the OEM exhausts. The NHRA factored horsepower was 250 horse for the 62-64 327/250, and 265 for the 62-65 327 300 horse engine. Someone should give it a try! Imagine a 327 265 in a Nova.Might be fun, especially with a 3 speed automatic.Interestingly enough,the 65 250 horse had either a WCFB or a 4 jet with 461 heads. Horsepower rating was the same as the earlier engine with the 520's. Last edited by Greg Reimer 7376; 05-05-2013 at 10:40 PM.