2 barrel analysis question

Joe DeMarzo · 03-22-2013, 09:31 PM

How does the Chevy 350 " 70 2 barrel at 1686 X 1375 compare to the "72 2 barrel at 1686 X 1260?

Is there a significant difference?

How about how much slower is the 2B to a 4B?

Thanks.

Lee Valentine · 03-23-2013, 07:05 AM

Joe, stick with the Q- Jet mileage won't be that much better with the 2 bbl. See you soon spring is coming I promise. Lee.

danny waters sr · 03-23-2013, 07:40 AM

Don't know about the 350 , but my 283 was a turtle with a 2bbl...

Everyone told me it would ,but i had to see for myself..........
One day wasted with that project.............

Billy Nees · 03-23-2013, 08:13 AM

Joe, there's a pretty big difference between the 2bbl that NHRA "accepts" on the 70 and the 71-72 2bbl. There's also major differences in the 70 and 72 engines if that's what you're looking at.
Give or take about a tenth one way or the other, you'll slow down a second.
Danny, the 2bbl that you had to use on the 283 is a small base 2g(same as my 307) and they're pretty horrible mainly because the top of the carb is so restricted. The 350s used a wide base 2g. There's one 283 stick Chevy II that did set a record with one though!

Tony Curcio · 03-23-2013, 04:47 PM

I have two experiences with the "big" two barrel.

In 2004 we compared Q-Jet vs 2 bbl on our 255-350 that was set up for IHRA pure stock at the time. It was a stick shift, with the mandated stock valve spring pressure and stock duration cam. The 2 bbl slowed it about .55 and it was further under the index, by about .15. We didn't need a rev limiter for either combo, it couldn't spin high enough to hurt itself.

Two years later, same car with a modern NHRA stocker engine and an automatic. This time the Q-Jet was further under the index by about .30 or more. As the difference between H/SA and M/SA is .70, this must mean it slowed 1.00 that day, although in my mind it was worse.

The 2 bbl was going through the traps at 5700, the 4 bbl at around 7000+. Changing the gears and converter probably would have helped, but we decided not to pursue it any farther.

Lee Valentine · 03-23-2013, 05:24 PM

I really think you guys are missing the point, Joe went from a big block to a small block then he read the post on cost per run and says to himself I have to go 2 bbl. I'll save on race gas. I'll be Angelo agrees with me.

Joe DeMarzo · 03-23-2013, 06:20 PM

Lee you are killing me.... I am laughing hard.

Thanks for the analysis.

So it would be a bad move I am guessing in '72 350/200.

James Perrone · 03-23-2013, 06:28 PM

Lee you think of everything...lol...

Dennis P Chapman · 03-23-2013, 06:44 PM

Quote:

Originally Posted by Joe DeMarzo

Lee you are killing me.... I am laughing hard.

Thanks for the analysis.

So it would be a bad move I am guessing in '72 350/200.

Joe.......Back away from the car seat down have a cigar the snow will go away.

Steve Calabro · 03-23-2013, 06:58 PM

Must be hanging out with Joe Zoom to much!

At least Zoom has an enclosed trailer! LOL

03-22-2013, 09:31 PM	#1
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 114 Times in 9 Posts	2 barrel analysis question How does the Chevy 350 " 70 2 barrel at 1686 X 1375 compare to the "72 2 barrel at 1686 X 1260? Is there a significant difference? How about how much slower is the 2B to a 4B? Thanks. __________________ Joe DeMarzo 1317 STK Last edited by Joe DeMarzo; 03-22-2013 at 09:48 PM.

03-23-2013, 07:05 AM	#2
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 322 Times in 68 Posts	Re: 2 barrel analysis question Joe, stick with the Q- Jet mileage won't be that much better with the 2 bbl. See you soon spring is coming I promise. Lee. __________________ Lee Valentine 1661 STK

03-23-2013, 07:40 AM	#3
danny waters sr VIP Member Join Date: Apr 2007 Location: lagrange,nc Posts: 2,224 Likes: 0 Liked 0 Times in 0 Posts	Re: 2 barrel analysis question Don't know about the 350 , but my 283 was a turtle with a 2bbl... Everyone told me it would ,but i had to see for myself.......... One day wasted with that project............. __________________ Danny Waters, Sr / 73 Duster "340"

03-23-2013, 08:13 AM	#4
Billy Nees VIP Member Join Date: Oct 2002 Location: On a hilltop in Pa. Posts: 4,233 Likes: 3,128 Liked 6,833 Times in 1,533 Posts	Re: 2 barrel analysis question Joe, there's a pretty big difference between the 2bbl that NHRA "accepts" on the 70 and the 71-72 2bbl. There's also major differences in the 70 and 72 engines if that's what you're looking at. Give or take about a tenth one way or the other, you'll slow down a second. Danny, the 2bbl that you had to use on the 283 is a small base 2g(same as my 307) and they're pretty horrible mainly because the top of the carb is so restricted. The 350s used a wide base 2g. There's one 283 stick Chevy II that did set a record with one though! __________________ Billy Nees 1188 STK, SS Reality, what a concept!

03-23-2013, 04:47 PM	#5
Tony Curcio Member Join Date: Mar 2002 Location: West Chester, PA Posts: 271 Likes: 1 Liked 4 Times in 1 Post	Re: 2 barrel analysis question I have two experiences with the "big" two barrel. In 2004 we compared Q-Jet vs 2 bbl on our 255-350 that was set up for IHRA pure stock at the time. It was a stick shift, with the mandated stock valve spring pressure and stock duration cam. The 2 bbl slowed it about .55 and it was further under the index, by about .15. We didn't need a rev limiter for either combo, it couldn't spin high enough to hurt itself. Two years later, same car with a modern NHRA stocker engine and an automatic. This time the Q-Jet was further under the index by about .30 or more. As the difference between H/SA and M/SA is .70, this must mean it slowed 1.00 that day, although in my mind it was worse. The 2 bbl was going through the traps at 5700, the 4 bbl at around 7000+. Changing the gears and converter probably would have helped, but we decided not to pursue it any farther. __________________ Tony Curcio 1860 STK

03-23-2013, 05:24 PM	#6
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 322 Times in 68 Posts	Re: 2 barrel analysis question I really think you guys are missing the point, Joe went from a big block to a small block then he read the post on cost per run and says to himself I have to go 2 bbl. I'll save on race gas. I'll be Angelo agrees with me. __________________ Lee Valentine 1661 STK

03-23-2013, 06:20 PM	#7
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 114 Times in 9 Posts	Re: 2 barrel analysis question Lee you are killing me.... I am laughing hard. Thanks for the analysis. So it would be a bad move I am guessing in '72 350/200. __________________ Joe DeMarzo 1317 STK

03-23-2013, 06:28 PM	#8
James Perrone VIP Member Join Date: Feb 2004 Location: LONG ISLAND N.Y. Posts: 1,599 Likes: 2,940 Liked 1,615 Times in 379 Posts	Re: 2 barrel analysis question Lee you think of everything...lol... __________________ james perrone 1290 STK

03-23-2013, 06:58 PM	#10
Steve Calabro Member Join Date: Jun 2007 Location: New Jersey Posts: 197 Likes: 208 Liked 40 Times in 11 Posts	Re: 2 barrel analysis question Must be hanging out with Joe Zoom to much! At least Zoom has an enclosed trailer! LOL __________________ Steve Calabro 1199 STK, SS Last edited by Steve Calabro; 03-23-2013 at 07:00 PM. Reason: more