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does this sound right? at 55mph tach reads 4000rpms #1041487 07/27/11 04:26 PM 07/27/11 04:26 PM
Joined: Jun 2011 Posts: 60 alaska K kmiller0024 OP member
kmiller0024 OP member K Joined: Jun 2011 Posts: 60 alaska	the car is a 72 charger with a 440/727 and the gear set is 3:55 with 15 inch tires. I've run 3:55 before and never had it this high. It acts like it has 4:10 or even lower. I didnt build the tranny but could a very high stall convertor do this? or maybe the tranny has been modified? It shifts very quickly to got to drive i cant drive this car unless i have a tanker follow me around :grin

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041488 07/27/11 04:36 PM 07/27/11 04:36 PM
Joined: Jan 2011 Posts: 492 Kansas BEINGmeISaCRIME mopar
BEINGmeISaCRIME mopar Joined: Jan 2011 Posts: 492 Kansas	Quote: the car is a 72 charger with a 440/727 and the gear set is 3:55 with 15 inch tires. I've run 3:55 before and never had it this high. It acts like it has 4:10 or even lower. I didnt build the tranny but could a very high stall convertor do this? or maybe the tranny has been modified? It shifts very quickly to got to drive i cant drive this car unless i have a tanker follow me around :grin Well a 15" tall tire will do that lol. Factory tachs could be way off but I'm sure if you think it's 4000 rpm then I'm sure you're prolly close. Seems like about 2500rpm would be realistic. I suppose a torque converter could cause some problem but I wouldn't think that much Last edited by 72charger; 07/27/11 04:43 PM.

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041489 07/27/11 04:46 PM 07/27/11 04:46 PM
Joined: Nov 2009 Posts: 2,177 ill D dennismopar73 top fuel
dennismopar73 top fuel D Joined: Nov 2009 Posts: 2,177 ill	NO NOT RIGHT ran 430 gear and a 28 tall tire was 3000 rpm at 58 mph 4000 something wrong!!

Re: does this sound right? at 55mph tach reads 4000rpms [Re: dennismopar73] #1041490 07/27/11 04:54 PM 07/27/11 04:54 PM
Joined: Apr 2010 Posts: 4,154 bethlehem pa M mikemee1331 master
mikemee1331 master M Joined: Apr 2010 Posts: 4,154 bethlehem pa	4:10 rear 55-60 is around 3000, 29 inch tire

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041491 07/27/11 04:56 PM 07/27/11 04:56 PM
Joined: Sep 2006 Posts: 1,139 West Tennessee R rbstroker super stock
rbstroker super stock R Joined: Sep 2006 Posts: 1,139 West Tennessee	This is going to sound like a smart *** answer, but is the tach switch set to 8 cylinder? Simple thing first.

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041492 07/27/11 05:32 PM 07/27/11 05:32 PM
Joined: Jan 2003 Posts: 26,032 Rio Linda, CA John_Kunkel Too Many Posts
John_Kunkel Too Many Posts Joined: Jan 2003 Posts: 26,032 Rio Linda, CA	What size 15" tires? Factory tach or aftermarket? Have you checked the speedo against a known distance/time? The INTERNET, the MISinformation superhighway

Re: does this sound right? at 55mph tach reads 4000rpms [Re: John_Kunkel] #1041493 07/27/11 05:51 PM 07/27/11 05:51 PM
Joined: Jan 2003 Posts: 33,005 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 33,005 Grand Prairie,Texas	Play with this to see what your rpms should be. http://vexer.com/automotive-tools/speed-rpm-calculator

Re: does this sound right? at 55mph tach reads 4000rpms [Re: stumpy] #1041494 07/27/11 05:55 PM 07/27/11 05:55 PM
Joined: Jan 2007 Posts: 780 Woodinville, WA Viol8r super stock
Viol8r super stock Joined: Jan 2007 Posts: 780 Woodinville, WA	Stuck in 2nd ? 1968 Pro-Touring Dodge Charger *2011 Optima Ultimate Street Car Challenge Invitee http://www.popularhotrodding.com/features/1203phr_1968_dodge_charger/index.html

Re: does this sound right? at 55mph tach reads 4000rpms [Re: rbstroker] #1041495 07/27/11 06:28 PM 07/27/11 06:28 PM
Joined: May 2005 Posts: 416 Franklin Co. Illinois runinonmt mopar
runinonmt mopar Joined: May 2005 Posts: 416 Franklin Co. Illinois	"This is going to sound like a smart *** answer, but is the tach switch set to 8 cylinder? Simple thing first." If the tach is set to 6 cyl. 3000 would read 3900 Ron A kid came in the shop with a '69 Roadrunner needing a new coil under warranty. He bragged about being able to shift at ten grand. I told him I could cure that. He said "no way" It was set on 4 cyl. In sixty-five I was seventeen and running up one-o-one I don't know where I'm running now, I'm just running on Jackson Browne-Running On Empty

Re: does this sound right? at 55mph tach reads 4000rpms [Re: runinonmt] #1041496 07/27/11 06:39 PM 07/27/11 06:39 PM
Joined: Sep 2003 Posts: 3,426 weymouth,mass. M meepmeep70 master
meepmeep70 master M Joined: Sep 2003 Posts: 3,426 weymouth,mass.	close to what i was seeing when i first bought my car,of course i was running ?"slicks and 4:86's,its what was in the car,but would check tach setting first,verfied there 3:55's?

Re: does this sound right? at 55mph tach reads 4000rpms [Re: meepmeep70] #1041497 07/27/11 07:13 PM 07/27/11 07:13 PM
Joined: Feb 2007 Posts: 370 NASHVILLE MAVERICKSHEMI enthusiast
MAVERICKSHEMI enthusiast Joined: Feb 2007 Posts: 370 NASHVILLE	Here ya go. This will Answer some questions for you. http://www.wallaceracing.com/Calculators.htm

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041498 07/27/11 08:54 PM 07/27/11 08:54 PM
Joined: Jun 2011 Posts: 60 alaska K kmiller0024 OP member
kmiller0024 OP member K Joined: Jun 2011 Posts: 60 alaska	this is a aftermarket tach, not a factory one and it is set on 8 i checked the speedo and its correct, i even pulled the gears to verify it was 3:55, it was stamped right on the side of the ring gear. and its not stuck in 2nd gear thanks for the replys going to go to some of the requested sites to help figure this out

Re: does this sound right? at 55mph tach reads 4000rpms [Re: kmiller0024] #1041499 07/27/11 08:58 PM 07/27/11 08:58 PM
Joined: Feb 2010 Posts: 2,806 Northern NJ StukaJU87 master
StukaJU87 master Joined: Feb 2010 Posts: 2,806 Northern NJ	Torque converter not working efficiently? I mean I have 3:55's and I am just about 3000rpm's at 60mph. Hughes street master converter-295/50-15's. Scott 1969 Super Bee, 383/4 speed

Re: does this sound right? at 55mph tach reads 4000rpms [Re: StukaJU87] #1041500 07/28/11 12:56 PM 07/28/11 12:56 PM
Joined: Jan 2003 Posts: 5,186 Wherever I am. J Junky master
Junky master J Joined: Jan 2003 Posts: 5,186 Wherever I am.	You mean the tire is 15" wide? I hope. I run 3.73's, 28" tire, foot break stall on TC is 2500 RPM. 2800 to 2900 RPM doing 60 mph. 2010 Black Challenger SE <> 3.5 V6 Custom Shift Knobs www.flameball.com Check It Out

Re: does this sound right? at 55mph tach reads 4000rpms [Re: Junky] #1041501 07/28/11 02:01 PM 07/28/11 02:01 PM
Joined: Apr 2010 Posts: 1,216 Under My Car Mopar_Country pro stock
Mopar_Country pro stock Joined: Apr 2010 Posts: 1,216 Under My Car	"does this sound right? at 55mph tach reads 4000rpms" No, I run 3.55's 26" tire and at 60 I'm right at 2900rpm.

Re: does this sound right? at 55mph tach reads 4000rpms [Re: Mopar_Country] #1041502 07/28/11 02:11 PM 07/28/11 02:11 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	4:10 gear, 24" tire 55mph = about 3200 rpm Go here... http://vexer.com/automotive-tools/speed-rpm-calculator "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: does this sound right? at 55mph tach reads 4000rpms [Re: Junky] #1041503 07/28/11 02:13 PM 07/28/11 02:13 PM
Joined: Jan 2003 Posts: 21,554 N.E. OHIO, USA A12 Too Many Posts
A12 Too Many Posts Joined: Jan 2003 Posts: 21,554 N.E. OHIO, USA	FWIW: '69 GTX 440 4-SPEED 3.54 Dana in 4th gear cruising on Ohio Turnpike (last week) at exactly 70 MPH with 255/60-15" BFG T/A tires....looks like 3500 RPM. Is 4th gear ratio close to 727 3rd gear/"D" ratio? MikeR 6751064-DSC05133rs160F.jpg (106 downloads)

Re: does this sound right? at 55mph tach reads 4000rpms [Re: A12] #1041504 07/28/11 02:21 PM 07/28/11 02:21 PM
Joined: Jan 2003 Posts: 21,554 N.E. OHIO, USA A12 Too Many Posts
A12 Too Many Posts Joined: Jan 2003 Posts: 21,554 N.E. OHIO, USA	I calculated a 255/60-15 tire should be 27.047244094488188976377952755906" tall for you perfectionists or rounded to 27.01" MikeR 6751085-DSC04678rsssss.jpg (113 downloads)

Re: does this sound right? at 55mph tach reads 4000rpms [Re: Mopar_Country] #1041505 07/28/11 02:34 PM 07/28/11 02:34 PM
Joined: Jan 2003 Posts: 16,123 Grand Haven, MI patrick I Live Here
patrick I Live Here Joined: Jan 2003 Posts: 16,123 Grand Haven, MI	Quote: "does this sound right? at 55mph tach reads 4000rpms" No, I run 3.55's 26" tire and at 60 I'm right at 2900rpm. I presume 15" rims...hard to say without tire size...235/60R15 are 26", 255/60 are 26", 275/60 are 28", 295/50 are 26", etc... IIRC, 3.55's and 27" tall tires, in 3rd (not OD) I'm at 3300 RPMS at 70... could be possible if you have a ton of converter slip, or you're stuck in 2nd.... 1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod SOLD!* 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)

Re: does this sound right? at 55mph tach reads 4000rpms [Re: patrick] #1041506 07/29/11 02:04 PM 07/29/11 02:04 PM
Joined: Jul 2007 Posts: 363 kentucky R roadrunner7020 enthusiast
roadrunner7020 enthusiast R Joined: Jul 2007 Posts: 363 kentucky	If you've checked the speedo is correct and the tach is set correctly you've either got a torque convector way out of it's efficiency range or are not getting into drive. I ran a 275/60/15 tire about 28 inches and a 727 with a 3000-3500 stall with 3.55s in the rear and 70 was about 3100-3250 and I was picking up convertor slippage at those speeds.

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