Gas question??

greg fulk · 11-01-2007, 02:49 AM

OK here's the thing....when i bought the car they ran C-12 in it.....I drained everything & put in Sunoco purple....car slowed a .10 what do i need to do to get the .10 back? NO I'm not going back to C-12!

LNorton · 11-01-2007, 05:53 AM

Greg, I dont know the exact difference from C-12 to Purple, but I would play with jetting and timing first. I know with our car going from 93 Pump to C-10(unleaded), I had to make a conisderable fuel and timing change to get it to run the same. 93 being the quicker of the two in the end. Stupid 93 will give us problems at nationals though.

Joe DeMarzo · 11-01-2007, 06:52 AM

Greg, it is in the jetting. I have used sunoco purple until this year and never saw any difference with the right jeting. In fact this year I used c-11, came in the car when I recieved it, changed to c-12 and it picked up .06. because it was to rich with the jetting. You will probably need to lean it out, C-12 burns hotter that the sunoco purple. Great article years ago about low compression motor and the rpm it takes to burn racing fuel, if I find it I will forward it.

Good Luck

Oldtimer · 11-01-2007, 10:15 AM

Its really caused by the viscosity, the rate of which the fuel goes thru the jet. Jetting is the correct answer.

greg fulk · 11-02-2007, 01:59 AM

Thanks guy! I was hoping it was timing....alot easier to change then jets (to me anyway i don't know a thing about a Q-jet) I can say one good thing the car runs pretty close...in bad air @ columbus 12.92 (week before sports nationals) to fall classic good air 12.77.....i can live with that. thing is car went 12.71 @ U.S. Nationals.

Joe DeMarzo · 11-02-2007, 07:03 AM

Greg, depending on the jets, you may only have to change the rods? What do you have in there currently for rods and jets?

Don Whitmore · 11-02-2007, 07:54 PM

Greg....if you can find any specs on Sunoco fuels, look for the RVP (Reid Vapor Pressure) and specific gravity to make adjustments. I've had no luck finding data on Sunoco fuels although it must be somewhere.

VP's C12 is more dense and higher RVP than C11 making jetting down necessary. Also,if you choose C11 and run it through the summer, try a cool can with it...,you'll be surprised.

junior barns · 11-02-2007, 10:23 PM

so low compression big block what fuel is best,c11,c12, or what? or is it all in jetting no diff in fuel.

Adger Smith · 11-02-2007, 10:25 PM

Go here: http://www.smithwholesalers.com/ & click on Race Fuels Some of the specs might be a little out of date, but it will give you the idea. Most fuel specs are listed in the chart.

Bob Bullock · 11-03-2007, 12:47 AM

Car went 12.75 first time out ever in extreme bracket mode. Then 12.71 at U.S. Nats. Since what ever you have done to the car has obviously slowed it down, the obvious course of action would be to go back to how it was when you took possession of it. Fuel or anything else. DUH!

11-01-2007, 02:49 AM	#1
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Gas question?? OK here's the thing....when i bought the car they ran C-12 in it.....I drained everything & put in Sunoco purple....car slowed a .10 what do i need to do to get the .10 back? NO I'm not going back to C-12! __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

11-01-2007, 05:53 AM	#2
LNorton Senior Member Join Date: Apr 2004 Location: RacerTees.com Posts: 505 Likes: 0 Liked 3 Times in 1 Post	Re: Gas question?? Greg, I dont know the exact difference from C-12 to Purple, but I would play with jetting and timing first. I know with our car going from 93 Pump to C-10(unleaded), I had to make a conisderable fuel and timing change to get it to run the same. 93 being the quicker of the two in the end. Stupid 93 will give us problems at nationals though. __________________ Lee Norton - N229 STK IHRA H/FIA - NHRA O/SA RacerTees.com

11-01-2007, 06:52 AM	#3
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 114 Times in 9 Posts	Re: Gas question?? Greg, it is in the jetting. I have used sunoco purple until this year and never saw any difference with the right jeting. In fact this year I used c-11, came in the car when I recieved it, changed to c-12 and it picked up .06. because it was to rich with the jetting. You will probably need to lean it out, C-12 burns hotter that the sunoco purple. Great article years ago about low compression motor and the rpm it takes to burn racing fuel, if I find it I will forward it. Good Luck __________________ Joe DeMarzo 1317 STK

11-01-2007, 10:15 AM	#4
Oldtimer Junior Member Join Date: Jul 2002 Location: Arkansas Posts: 87 Likes: 0 Liked 0 Times in 0 Posts	Re: Gas question?? Its really caused by the viscosity, the rate of which the fuel goes thru the jet. Jetting is the correct answer. __________________ Bob Pagano L88BOB@aol.com www.dyainc.org 4033 AA/SA

11-02-2007, 01:59 AM	#5
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: Gas question?? Thanks guy! I was hoping it was timing....alot easier to change then jets (to me anyway i don't know a thing about a Q-jet) I can say one good thing the car runs pretty close...in bad air @ columbus 12.92 (week before sports nationals) to fall classic good air 12.77.....i can live with that. thing is car went 12.71 @ U.S. Nationals. __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

11-02-2007, 07:03 AM	#6
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 114 Times in 9 Posts	Re: Gas question?? Greg, depending on the jets, you may only have to change the rods? What do you have in there currently for rods and jets? __________________ Joe DeMarzo 1317 STK

11-02-2007, 07:54 PM	#7
Don Whitmore Member Join Date: Aug 2004 Location: Central Illinois Posts: 140 Likes: 0 Liked 0 Times in 0 Posts	Re: Gas question?? Greg....if you can find any specs on Sunoco fuels, look for the RVP (Reid Vapor Pressure) and specific gravity to make adjustments. I've had no luck finding data on Sunoco fuels although it must be somewhere. VP's C12 is more dense and higher RVP than C11 making jetting down necessary. Also,if you choose C11 and run it through the summer, try a cool can with it...,you'll be surprised.

11-02-2007, 10:23 PM	#8
junior barns Senior Member Join Date: Jun 2006 Posts: 539 Likes: 11 Liked 20 Times in 14 Posts	Re: Gas question?? so low compression big block what fuel is best,c11,c12, or what? or is it all in jetting no diff in fuel.

11-02-2007, 10:25 PM	#9
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,348 Likes: 434 Liked 677 Times in 261 Posts	Re: Gas question?? Go here: http://www.smithwholesalers.com/ & click on Race Fuels Some of the specs might be a little out of date, but it will give you the idea. Most fuel specs are listed in the chart. __________________ Adger Smith (Former SS) Last edited by Adger Smith; 11-02-2007 at 10:28 PM. Reason: S/P

11-03-2007, 12:47 AM	#10
Bob Bullock Junior Member Join Date: Nov 2006 Location: Illinois Posts: 39 Likes: 0 Liked 0 Times in 0 Posts	Re: Gas question?? Car went 12.75 first time out ever in extreme bracket mode. Then 12.71 at U.S. Nats. Since what ever you have done to the car has obviously slowed it down, the obvious course of action would be to go back to how it was when you took possession of it. Fuel or anything else. DUH!