What is the best way to kill 4-5 tenths for index racing?
#2037857
03/24/16 04:21 PM
03/24/16 04:21 PM
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Joined: Dec 2013
Posts: 4,704 Wichita
GY3
OP
master
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OP
master
Joined: Dec 2013
Posts: 4,704
Wichita
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: GY3]
#2037862
03/24/16 04:25 PM
03/24/16 04:25 PM
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Joined: Jan 2003
Posts: 13,400 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,400
Marion, South Carolina [><]
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With the Camaro, we used to kill a few tenths by changing the launch rpm and adding tire pressure so the slicks slipped a little. It worked great for the 6.0 index class (1/8 mile) we used to run. The car would go 5.70s in good air.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: Dragula]
#2037893
03/24/16 05:02 PM
03/24/16 05:02 PM
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Joined: Jan 2003
Posts: 580 Livermore, CA
Dduster
mopar
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mopar
Joined: Jan 2003
Posts: 580
Livermore, CA
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We use a little trick and move the linkage up one hole on the carburetor. Went from 9.83 to 10.11 and didn't skip a beat. How much rpm did You lose on the top end to lose 0.4 sec?
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: GY3]
#2037901
03/24/16 05:15 PM
03/24/16 05:15 PM
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Joined: Dec 2005
Posts: 11,704 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,704
Fulton County, PA
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Weight. Timing. Shift points. I wouldn't get excessive with retarding the timing. 3 speed footbrake? Try leaving in second gear and see what it does. Maybe a mechanical stop like a Moroso 65042 or 65040 if you can find one. You may be surprised how much you have to do to kill that much. Try unhooking the secondaries once to see what that does.
If the results don't match the theory, change the theory.
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: GY3]
#2037938
03/24/16 06:07 PM
03/24/16 06:07 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I use a mech throttle stop plus I lower the launch rpm and the shift rpm to drop 1 full second.. the mech throttle stop is set at about 1/3 throttle then the lower rpms.. slows me from 8.96 to 10.00.... in your case I would believe the lower launch rpm and shift rpm would be good enough
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: nss guy]
#2037986
03/24/16 07:37 PM
03/24/16 07:37 PM
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Joined: Dec 2005
Posts: 11,704 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,704
Fulton County, PA
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What type of index racing? What are the rules? Throttle stops on a timer are the best bet if allowed MSD Grid with programmable timing retards if allowed If no electronic aids allowed, retard the cam and use weight 4-5 tenth's is a lot to kill and be consistent
95% of what I race is on an index Actually slowing 4 or 5 tenths with a typical .90 type timed stop where you leave at WOT, is a lot harder to do and be consistent than it is to kill a second and a half with that set up. Has to do with stop ratios and keeping it predictable. Basically you would just be blipping the throttle. Much harder to do and be consistent than if it's on the stop for maybe 2 seconds.
If the results don't match the theory, change the theory.
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: GY3]
#2038000
03/24/16 08:00 PM
03/24/16 08:00 PM
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Joined: Oct 2009
Posts: 1,267 North, Alabama
D-50
pro stock
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pro stock
Joined: Oct 2009
Posts: 1,267
North, Alabama
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I went to T&T last year to see if I could slow my D50 down for the 7.0 index. I was running in the low 6.30's that night. I usually shift at 6800. I tried shifting at 5600 and it would only slow down to a 6.50. I need full throttle to leave on a Pro Tree (4 tenths).
1.33 60 ft,6.21 at 110.59 in the 1/8, pump gas small block,2950lbs,drag radials,mufflers and driven to track ...
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: GY3]
#2038003
03/24/16 08:07 PM
03/24/16 08:07 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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If you can you can, slide the throttle cable housing forward to give you less throttle... it takes a lt more than you think
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Re: What is the best way to kill 4-5 tenths for index racing?
[Re: MR_P_BODY]
#2038011
03/24/16 08:33 PM
03/24/16 08:33 PM
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Joined: Aug 2003
Posts: 4,991 new jersey usa
11secdart
master
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master
Joined: Aug 2003
Posts: 4,991
new jersey usa
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I have been using the Moroso mechanical stop p/n 65042 ( modified with a longer threaded rod) for over 8 years now and have been very successful with it. I am slowing about 8-9 tenths on average. I use it to slow down to 11.50 for Street Eliminator and for 11.50 index racing. Electronic and air operated stops aren`t allowed in the classes I run. I considered a plate system, did some research and talked to racers using them and came to the conclusion that my system is best for my combo. I have seen some of my fellow competitors using weight and shift points to slow but again i feel my setup works better. A word of advice: if you use the Moroso setup be sure and use a throttle linkage bracket like one from Jegs etc. so a second bolt can be used to attach the stop as it will tend to move if used only using the carb bolt. As a matter of fact I am going this Saturday to a Test and Tune to get the stop dialed in for my new motor combination.
Last edited by 11secdart; 03/25/16 12:19 PM.
68 Dart 410 / 904 92 D150 original owner 21 Ram 1500 Quad Cab, Big Horn , Hemi ,4x4 23 Audi Q5 16 Honda HRV
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