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Author
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Topic: Cam and Torque Converter?
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69stanger
Journeyman Posts: 77
From: Northridge, CA
Registered: Aug 2002
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posted 10-19-2002 11:11 PM
  
I know this is a dumb question but Im very curious to know the answer:why is that some mild cams require you to upgrade your torque converter? couldnt you just gear it up to make you reach your desired rpm range quicker?
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 10-20-2002 12:01 AM
Higer duration that is built into them takes away bottom end torque. That requires a little more RPM to help get the engine in the power range.  ------------------
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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Rory McNeil
Gearhead Posts: 1687
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 10-20-2002 08:37 PM
On a mild engine, it doesn`t take much cam to really hurt bottom end torque. When I first starting to modify my 78 Fairmonts 302, the first step was replacing the 2.47  geared 7.5 rearend for a 8.8 with 3.55`s, & installing a pair of cheapo Hedman 1 1/2" full length headers, with OE dual exhaust (no cats) from a 88 5.0 Mustang. With the stock cam & 2 barrel setup, it knocked a full second of my 1/4 mile ET, shifting at 4500rpm. (from 16.2ET to 15.2) Next step was a 84-85 5.o Mustang OE lowrise alum. intake & a 450 cfm Holley 4V carb, which made a very minor improvement.Think the stock cam was holding it back, I bought a pretty mild "Blue Racer" cam&lifter kit(.448I, .472"E lift, 204I, 214E duration @ .050 lift.).By most standards, quite a small cam by most standards, but it really hurt the cars low end. In fact the car actually ran slower ET`s by a bit, even though it ran about 1/2 mph faster. I tried new valve springs, fuel pump etc, but it wouldn`t pick up, UNTIL I put in a 2500 stall B&M convertor. That made a big difference, knocking over 4/10`s of the ET.Like I said before, even a fairly small cam could benefit from a bit more convertor.------------------
78 Fairmont 428 4 speed 10.20@130mph
80 Fairmont 302 5 speed 12.8@105mph
85 Mustang NHRA Stocker under construction, 302 5 speed
59 Meteor (Canadian Ford) 2 dr sedan 332, auto
74 F350 ramp truck 390 4spd
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mustangboy
Gearhead Posts: 1147
From: Ont, Canada
Registered: Mar 2002
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posted 10-21-2002 09:32 AM
I have a neat article from a magazine comparing gear swaps and converter swaps.The cars is a fairly mild 68 Chevy Nova. Gear ratio 3.00 11 inch converter 60ft 2.10 [email protected]/ Change to 3.50 gears,60ft 1.99 ET 13.40@ 102.59/ Change to 4.11 gears 60ft 1.95 ET [email protected]/Change to 4.57 gears 60ft 1.90 ET [email protected] Now they changed the converter from a 11 inch to a 10 inch and went through all the same gear swaps GR-3.00 60ft 1.99 ET [email protected]/ GR-3.50 60ft 1.93 ET [email protected]/ GR-4.11 60ft 1.85 ET [email protected]/ GR-4.57 60ft 2.01 ET [email protected] said on the last run the car slowed because it was getting above the cams power range(5500) and they had a little wheelspin.Its interesting to compare the converter to the gear swaps and see which would be the better swap if you were doing just one. Sorry guys this looked much more impressive when the times were all in a row,from top to bottom but it went all to hell when I submitted it.  I guess I'll have to get the wife to show me how to do that.)  [This message has been edited by mustangboy (edited 10-21-2002).] [This message has been edited by mustangboy (edited 10-21-2002).]
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69stanger
Journeyman Posts: 77
From: Northridge, CA
Registered: Aug 2002
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posted 10-21-2002 12:43 PM
here let me see if I an help organize this infotest car: 68 Chevy Nova 60ft ET Gear-ratio converter finish 60mph
2.10 [email protected] 3.00 11 4200 2600
1.99 [email protected] 3.50 11 4600 2900
1.95 [email protected] 4.11 11 5500 3300
1.90 [email protected] 4.57 11 6000 3500 1.99 [email protected] 3.00 10 4600 2950
1.93 [email protected] 3.50 10 5000 3100
1.85 [email protected] 4.11 10 5500 3300
2.01 [email protected] 4.57 10 6000 3500 [This message has been edited by 69stanger (edited 10-22-2002).] [This message has been edited by 69stanger (edited 10-22-2002).]
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mustangboy
Gearhead Posts: 1147
From: Ont, Canada
Registered: Mar 2002
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posted 10-21-2002 02:06 PM
Thanks 69stanger thats what it was suppposed to look like.If I could have done that there was even more info like the rpms at 60 mph and through the traps.
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69stanger
Journeyman Posts: 77
From: Northridge, CA
Registered: Aug 2002
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posted 10-21-2002 08:42 PM
quote:
Originally posted by mustangboy:
Thanks 69stanger thats what it was suppposed to look like.If I could have done that there was even more info like the rpms at 60 mph and through the traps.
could you please post the the rest of the info
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mustangboy
Gearhead Posts: 1147
From: Ont, Canada
Registered: Mar 2002
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posted 10-21-2002 11:45 PM
Ok since I still can't get it to line up from top to bottom I'll just write the rpms at the finish line and at 60 mph in the same order you typed them out from top to bottom.Also car had 10.5x26 slicks.#1 rpm@finish 4200 @ 60mph 2600 #2 4600 and 2900 #3 5500 and 3300 #4 6000 and 3500 #5 4600 and 2950 #6 5000 and 3100 #7 5500 and 3300 #8 6000 and 3500.I hope you can make sense of this again.The whole point of the article is to show that a good converter swap can give you as big a gain as a gear swap in some situations.
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69stanger
Journeyman Posts: 77
From: Northridge, CA
Registered: Aug 2002
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posted 10-22-2002 12:18 AM
thanks mustangboy for that article it really helped.
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mustangboy
Gearhead Posts: 1147
From: Ont, Canada
Registered: Mar 2002
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posted 10-22-2002 12:13 PM
Glad I could help ------------------
1968 mustang j-code sprint.13.69@101 1963Falcon waiting for a rebirth.
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