Making the car more consistent

JWhis · 06-20-2011, 09:57 AM

Just looking for a few idea's to start somewhere as to why my car runs off so much out of no where. Saturday it was in the 13.69's 2 time trials and first round, 2nd round came along and it goes a 13.637. Also when the car picks up it seems to be all the way down the track not just at the 1/8 mile or 1000" .Tire pressure is the same front and back stage the same shift at 5k 2nd and 3rd. I'm stumped on what to look for at this point. It's a 73 challenger 340/727 650 holley carb, edelbrock performer rpm intake other than that it's a stock motor (#'s matching actually) Any idea's would be much appreciated.

Phillip marvetz · 06-20-2011, 12:14 PM

Does it usually pick up like that after 3 or 4 runs? or did the air change a bit? What does it have for stall? How old is the trans? 727 or 904? I assume this is a street car?

JWhis · 06-20-2011, 12:37 PM

Usually it will just throw an odd ball run in there sometimes it could do it on the 2nd time pass. The Air did get a little better. That 2nd round I ran an 18 second SUV and he went .02 under his dial. Converter is a turbo action 4200 Stall converter. The Trans is a 727 it's the original that came with the car. I have had it looked at and also adjusted by Danny Crawley local racer that does Transmissions. He also put reverse manual valve body in the transmission as well. Yes I do drive it to the track but that is about it.

1320racer · 06-20-2011, 02:53 PM

consistency starts and ends with the knucklehead wearing the brain bucket

That said, if the car goes from A to B pulling from the hit of the throttle to the stripe without a hint of an issue that's half the battle if not, you need to fix the mechanical issues first.

The other half is up to you. Start by leaving the hood closed between rounds, meaning don't change, adjust or screw with anything.

Make sure water temp is exactly the same every pass, burnout duration is exactly the same every pass, launch RPM is exactly the same every pass, shift points are exactly the same every pass and you are putting the car into the beams at exactly the same spot every time.

Are you observing and recording weather before every run and observing the flag?

JWhis · 06-20-2011, 03:08 PM

I don't adjust or change anything at the track. All the other stuff i do exactly that. I have been making note of the weather but not the flag, But that wouldn't cause it to pick up that much, at least i don't think?

1320racer · 06-20-2011, 03:56 PM

Post all 3 time slips, both time trials and first round

JWhis · 06-20-2011, 06:37 PM

Phillip marvetz · 06-21-2011, 01:01 AM

Looks like the second time slip should have been the fastest/quickest to me. Does the direction of the wind change much? Is the carb a vacuum secondary or a double pumper?

JWhis · 06-21-2011, 08:07 AM

it's a double pumper and no i don't notice it changing much. I'm starting to think it's just me in the car. Maybe i am letting it bother me too much.

Phillip marvetz · 06-21-2011, 09:41 AM

The carb is smaller than I would use, If the weather changes it will affect the small carb more. Does it have a hydraulic cam?

06-20-2011, 09:57 AM	#1
JWhis Junior Member Join Date: Mar 2011 Location: Indianapolis,IN Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Making the car more consistent Just looking for a few idea's to start somewhere as to why my car runs off so much out of no where. Saturday it was in the 13.69's 2 time trials and first round, 2nd round came along and it goes a 13.637. Also when the car picks up it seems to be all the way down the track not just at the 1/8 mile or 1000" .Tire pressure is the same front and back stage the same shift at 5k 2nd and 3rd. I'm stumped on what to look for at this point. It's a 73 challenger 340/727 650 holley carb, edelbrock performer rpm intake other than that it's a stock motor (#'s matching actually) Any idea's would be much appreciated. __________________ Jason Whisman

06-20-2011, 12:14 PM	#2
Phillip marvetz Senior Member Join Date: Oct 2008 Location: Lynden ,WA Posts: 820 Likes: 0 Liked 3 Times in 3 Posts	Re: Making the car more consistent Does it usually pick up like that after 3 or 4 runs? or did the air change a bit? What does it have for stall? How old is the trans? 727 or 904? I assume this is a street car? __________________ 2009 V/SA Record Holder

06-20-2011, 12:37 PM	#3
JWhis Junior Member Join Date: Mar 2011 Location: Indianapolis,IN Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Re: Making the car more consistent Usually it will just throw an odd ball run in there sometimes it could do it on the 2nd time pass. The Air did get a little better. That 2nd round I ran an 18 second SUV and he went .02 under his dial. Converter is a turbo action 4200 Stall converter. The Trans is a 727 it's the original that came with the car. I have had it looked at and also adjusted by Danny Crawley local racer that does Transmissions. He also put reverse manual valve body in the transmission as well. Yes I do drive it to the track but that is about it. __________________ Jason Whisman

06-20-2011, 02:53 PM	#4
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 1,776 Likes: 70 Liked 398 Times in 189 Posts	Re: Making the car more consistent consistency starts and ends with the knucklehead wearing the brain bucket That said, if the car goes from A to B pulling from the hit of the throttle to the stripe without a hint of an issue that's half the battle if not, you need to fix the mechanical issues first. The other half is up to you. Start by leaving the hood closed between rounds, meaning don't change, adjust or screw with anything. Make sure water temp is exactly the same every pass, burnout duration is exactly the same every pass, launch RPM is exactly the same every pass, shift points are exactly the same every pass and you are putting the car into the beams at exactly the same spot every time. Are you observing and recording weather before every run and observing the flag?

06-20-2011, 03:08 PM	#5
JWhis Junior Member Join Date: Mar 2011 Location: Indianapolis,IN Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Re: Making the car more consistent I don't adjust or change anything at the track. All the other stuff i do exactly that. I have been making note of the weather but not the flag, But that wouldn't cause it to pick up that much, at least i don't think? __________________ Jason Whisman

06-20-2011, 03:56 PM	#6
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 1,776 Likes: 70 Liked 398 Times in 189 Posts	Re: Making the car more consistent Post all 3 time slips, both time trials and first round

06-20-2011, 06:37 PM	#7
JWhis Junior Member Join Date: Mar 2011 Location: Indianapolis,IN Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Re: Making the car more consistent __________________ Jason Whisman

06-21-2011, 01:01 AM	#8
Phillip marvetz Senior Member Join Date: Oct 2008 Location: Lynden ,WA Posts: 820 Likes: 0 Liked 3 Times in 3 Posts	Re: Making the car more consistent Looks like the second time slip should have been the fastest/quickest to me. Does the direction of the wind change much? Is the carb a vacuum secondary or a double pumper? __________________ 2009 V/SA Record Holder

06-21-2011, 08:07 AM	#9
JWhis Junior Member Join Date: Mar 2011 Location: Indianapolis,IN Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Re: Making the car more consistent it's a double pumper and no i don't notice it changing much. I'm starting to think it's just me in the car. Maybe i am letting it bother me too much. __________________ Jason Whisman

06-21-2011, 09:41 AM	#10
Phillip marvetz Senior Member Join Date: Oct 2008 Location: Lynden ,WA Posts: 820 Likes: 0 Liked 3 Times in 3 Posts	Re: Making the car more consistent The carb is smaller than I would use, If the weather changes it will affect the small carb more. Does it have a hydraulic cam? __________________ 2009 V/SA Record Holder