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Author
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Topic: consistency problem and ???
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-19-2002 09:38 PM
   
OK, Last Wednesday night we ran the car still jetted lean, 83/85 from the finals at 4,000 feet and all corked up. Usual jetting is 85/88. Anyway, the last three runs were 10.92, 10.97(lifting), so for the next round we dial a 10.95 and run a 10.85.  I'll throw out the lifting run and show the other two slips. 60' 1.472
330' 4.398
1/8mi 6.878 mph 98.24
1000' 9.058
1/4mi 10.924 mph 120.14 60' 1.474
330' 4.373
1/8mi 6.837 mph 98.90
1000' 8.998
1/4mi 10.850 mph 120.76 The 60'er was about the same, but it ran a tenth quicker! Any ideas? We just can't dial this car..... SteveW
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 10-19-2002 11:17 PM
How much time passed between these two runs?
Do you have weather conditions for both of them? Was the car at the same temp for the run?
Sorry to throw all these questions but as you know they make a big difference.
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 10-19-2002 11:59 PM
How about possibly the shift points are varying a bit?????  ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-20-2002 12:10 AM
quote:
Originally posted by 70coupe:
How much time passed between these two runs?
Do you have weather conditions for both of them? Was the car at the same temp for the run?
Sorry to throw all these questions but as you know they make a big difference.
Yeah weather kept getting colder throughout the night and the d/a lowered about 400'. The temp of the engine stayed the same for each run. Maybe not the tranny thou... Good points! SteveW
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-20-2002 12:13 AM
quote:
Originally posted by Moneymaker:
How about possibly the shift points are varying a bit?????
Alex, That's always a posibility. I'll have to get a play back tach for Christmas.  From the 60's and the mph the two runs should have been closer than they were. She's shifting off the light set at 6200 but who knows? SteveW
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 10-20-2002 12:28 AM
Steve, I'll bet on the shift points as the key to the inconsistancy. 60 foots are too close to be anything else. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
IP: Logged |
steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-20-2002 12:56 AM
I hear ya Alex!
Thanks again,SteveW
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Fastymz
Moderator Posts: 21275
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 10-20-2002 02:21 AM
Steve I know I'm no help but those 60 foot times are sweet. SCOOP ------------------
2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8"3.40 TracLoc,Cragar SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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Rory McNeil
Gearhead Posts: 1687
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 10-20-2002 02:42 AM
Steve, both your 1/8th & 1/4 mile MPH were at least 1/2 MPH better, weather conditions could very well made the diffence.
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 10-20-2002 06:29 AM
I know everyones car is different but for 400' difference my car runs .015 for every 100' better. So, I would have gained about .06 in ET. Which would have been a 10.86 corrected for you. (close!)
Brian
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-20-2002 11:41 PM
Thanks Guys!I've got it jetted up to 85/89 so we'll see how it does in the Fall air. I think I'll chip the shift light to 6000 too, shifting early probably runs quicker than late. Let the convertor "eat". SteveW
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 10-21-2002 12:22 AM
quote:
Originally posted by steve'66:
I think I'll chip the shift light to 6000 too, shifting early probably runs quicker than late. Let the convertor "eat". SteveW
Steve,
It's funny you should mention that. I have a 4900 rpm converter and I normaly shift at 6500. The other day I accidentally short shifted at about 5800 and the car went a couple hundredths quicker. I reasoned that the RPMs dropped down below the converter flash point and multiplied my torque a little bit. Is there anything to this or what do you make of it? Should I be shifting this low all of the time? ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 10-21-2002 10:13 AM
Well, that does come into play in certain applications. Probably 90% of the NHRA/IHRA stock eliminator cars have very loose converters intentionaly just to create that scenario. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
IP: Logged |
kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 10-21-2002 12:07 PM
And here I am contemplating getting my convertor tightened up a bit. The originall stall was around 5600, its nowing going 6000 all the time, and seeing over 6200 in good air, and more in "great" air.
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 10-21-2002 01:05 PM
quote:
Originally posted by Moneymaker:
Well, that does come into play in certain applications. Probably 90% of the NHRA/IHRA stock eliminator cars have very loose converters intentionaly just to create that scenario.
That's very,very interesting! ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V [This message has been edited by clevelandstyle (edited 10-21-2002).]
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 10-21-2002 01:27 PM
Another interesting thing is that I've been playing with my gear ratio. My quickest times came with 4.11 gear and 27.5" BFG drag radials. I figured I could 60 ft. better with a 28" slick and 4.56 gear, but it slowed down. I then put the 4.11s back in still using the slicks and the car picked back up, but still hasn't matched the BFG drag radials. BTW, traction has never been a problem. It hooks every time. My point is, the car likes the 4.11 gear, as opposed to the 4.56. I think it is using the converter better. ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-21-2002 02:03 PM
Ben,We're running a 3.89 gear and 26" tall M/T slicks. But our power curve is lower than you guys' clevelands. Goes thru the traps at 6400 rpm, shifting at 6200+. Another question,
How much higher does the rpm reach after you see the shift light and before the tranny actually changes gears. It could be 200 rpm on the 1-2 shift pretty easily right? SteveW
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 10-21-2002 02:16 PM
At least.On my motor, using my printer interface that plugs into my playback tach, with a 7k chip in the lite, on each pass by time I see the light, pull the gear, and the trans actually shifts, its at 7500 rpm, everytime. I thought I was late, till all the printouts were in the same area. On the 2-3 shift, it only gains about 200 rpm.
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-21-2002 03:23 PM
Rob,We may be onto something.... The shift light is 6200 and the rev limiter is 6500. 
It may be touching the limiter during some runs. Even though we haven't noticed it. SteveW
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 10-21-2002 06:36 PM
I have a memory tach that just picks up the peak rpm. When the shift light is set at 6500, the memory tach has been peaking at 6800-6900 on the shifts. I don't know if it is on the first shift or the second one.------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
IP: Logged |
clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 10-21-2002 06:46 PM
quote:
Originally posted by steve'66:
Rob,We may be onto something.... The shift light is 6200 and the rev limiter is 6500.
It may be touching the limiter during some runs. Even though we haven't noticed it. SteveW
Steve,
You are getting really close to the limiter on the top end, too. Going through the traps at 6400 and the limit is set at 6500.
------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 10-21-2002 07:30 PM
Shifting on time is shifting on time Steve, whether it's done by a sissy shifter and a chip, or manualy the Real mans(or woman's) way.
I have always liked to set the shift light a little on low side to allow for some "oops" factor. One way to test your (Mel's) consistancy in shifting is to lower the shift point to say 6000 and leave all else alone. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
IP: Logged |
steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 10-21-2002 09:45 PM
6,000 shiftpoint it is. Thanks, SteveW
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