Switch to 2bbl - Page 2

Coleydog · 12-15-2017, 02:52 PM

Well you got me thinking, just checked on a 318 mopar in 70 & 69, 70 was 185, 69 - 172. Really, was there that much difference between the two? Hope someone who runs one can chime in.
Sorry if I jumped rails here.
Mike
The factor for the 70 is 15.32 and the 69 is 16.70. What class are these?
Mike

David Lee · 12-15-2017, 03:44 PM

Quote:

Originally Posted by Coleydog

Well you got me thinking, just checked on a 318 mopar in 70 & 69, 70 was 185, 69 - 170. Really, was there that much difference between the two? Hope someone who runs one can chime in.
Sorry if I jumped rails here.
Mike

its funny the 318 in 68 is rated higher, even though its the same engine. I am going to asdk the powers that be to get the lower rating on the 68

HR9121 · 12-15-2017, 06:30 PM

Quote:

Originally Posted by Coleydog

Well you got me thinking, just checked on a 318 mopar in 70 & 69, 70 was 185, 69 - 172. Really, was there that much difference between the two? Hope someone who runs one can chime in.
Sorry if I jumped rails here.
Mike
The factor for the 70 is 15.32 and the 69 is 16.70. What class are these?
Mike

70 would be O/S and the 69 would run P/S

Coleydog · 12-15-2017, 10:50 PM

Quote:

Originally Posted by HR9121

70 would be O/S and the 69 would run P/S

Thanks, but finally figured out where to find that.

Mark Yacavone · 12-15-2017, 11:11 PM

Mr Money, It really doesn't matter what the exact number is. Both will run way under.
They run J and K/SA with a 4 bbl ,and R and T with a 2bbl, and you're better off being in R and T.

Dwight Southerland · 12-16-2017, 09:28 AM

Quote:

Originally Posted by Coleydog

Thanks, but finally figured out where to find that.

You're not using http://www.classracerinfo.com?? Shame on you!!

Chipper Chapman · 12-16-2017, 10:54 AM

If you were to get a proper 2bbl camshaft ground how much would it differ from a 4bbl grind? I’m under the assumption that you’d want less duration when you go from a 800cfm q jet to a 350cfm 2bbl. Thought hard about doing this with 350/255 before selling, I didn’t think there’d be much difference in the 69-71 350 going from 750 to 500 cfm but these later engines loose a lot more airflow capability

Coleydog · 12-16-2017, 11:38 AM

Quote:

Originally Posted by Dwight Southerland

You're not using http://www.classracerinfo.com?? Shame on you!!

I've used it many times, just didn't look in the right place, now I know. Great info and very helpful.

rboyle · 12-17-2017, 04:10 PM

So am I looking at about .5 slower for my 1973 Nova 350/175/287 horse set up? .390/.410 lift cam, good 882 heads, Boburka 207 quadrajet, dish pistons, metric 200 trans with 5.13 rear. Car weighs 3470 in H/SA but would weigh 3418 in L/SA with a 2 barrel setup. I figured it at .90 better minus the .5 tenths loss on a carb swap so overall about .4 tenths better class for my combo? Does this sound right?

rboyle · 12-17-2017, 04:13 PM

The index is .85 better and 50 lbs less so about .90 better but car slows up about .5 because of restrictive 2 bbl carb.

12-15-2017, 02:52 PM	#11
Coleydog Senior Member Join Date: Jul 2014 Posts: 569 Likes: 36 Liked 53 Times in 38 Posts	Re: Switch to 2bbl Well you got me thinking, just checked on a 318 mopar in 70 & 69, 70 was 185, 69 - 172. Really, was there that much difference between the two? Hope someone who runs one can chime in. Sorry if I jumped rails here. Mike The factor for the 70 is 15.32 and the 69 is 16.70. What class are these? Mike Last edited by Coleydog; 12-15-2017 at 05:44 PM.

12-15-2017, 11:11 PM	#15
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,814 Likes: 2,903 Liked 5,118 Times in 1,950 Posts	Re: Switch to 2bbl Mr Money, It really doesn't matter what the exact number is. Both will run way under. They run J and K/SA with a 4 bbl ,and R and T with a 2bbl, and you're better off being in R and T. __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

12-16-2017, 10:54 AM	#17
Chipper Chapman Member Join Date: Jan 2004 Location: Belmont N.S. Canada Posts: 473 Likes: 246 Liked 166 Times in 71 Posts	Re: Switch to 2bbl If you were to get a proper 2bbl camshaft ground how much would it differ from a 4bbl grind? I’m under the assumption that you’d want less duration when you go from a 800cfm q jet to a 350cfm 2bbl. Thought hard about doing this with 350/255 before selling, I didn’t think there’d be much difference in the 69-71 350 going from 750 to 500 cfm but these later engines loose a lot more airflow capability __________________ Chris Chapman 1969 Chevelle NHRA F-G/SA 1090

12-17-2017, 04:10 PM	#19
rboyle Senior Member Join Date: Jan 2015 Posts: 604 Likes: 1,454 Liked 586 Times in 162 Posts	Re: Switch to 2bbl So am I looking at about .5 slower for my 1973 Nova 350/175/287 horse set up? .390/.410 lift cam, good 882 heads, Boburka 207 quadrajet, dish pistons, metric 200 trans with 5.13 rear. Car weighs 3470 in H/SA but would weigh 3418 in L/SA with a 2 barrel setup. I figured it at .90 better minus the .5 tenths loss on a carb swap so overall about .4 tenths better class for my combo? Does this sound right?

12-17-2017, 04:13 PM	#20
rboyle Senior Member Join Date: Jan 2015 Posts: 604 Likes: 1,454 Liked 586 Times in 162 Posts	Re: Switch to 2bbl The index is .85 better and 50 lbs less so about .90 better but car slows up about .5 because of restrictive 2 bbl carb.