390 RPM's

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May 20, 2004 | 08:07 PM

#16

RapidRuss

FE "Freakin Expensive"

Joined: Dec 2003

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From: Smith Mountain Lake, VA

Ya Barry I dont care for those numbers...at all... I might be back out in Cal...the last of july or the begining of Aug?

I guess I better stop (Hi jacking A post) LOL!! -Russ

May 20, 2004 | 11:29 PM

#17

cleanLX

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Joined: Mar 2003

Posts: 541

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From: Phoenix Az, by way of Fre

Quote:

Originally Posted by fordman428

sorry about that russ i was running my combo, when i typed in 25" tires, 4.11 gears at 65 mph it said 3860rpms.

25" Tires on a 16+" rim!?
That means you are running... what? 225/40-16's?
Stock 8.75x16.5's are 29"

May 21, 2004 | 01:43 AM

#18

fordeverpower

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Joined: Jul 2003

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From: iowa

easy clean lx, we know the 250 has 16.5 inch rims. The 25 inch was a typo. I think 215 75r 15 are 25 inches which are on F150's.

May 21, 2004 | 07:16 AM

#19

fordman428

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Joined: Nov 2003

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From: Iowa

i guess ill say it again, i was running my OWN trucks combo, my truck is not a 250, it has 15 in wheels, 25 in tires.

May 21, 2004 | 08:23 AM

#20

cleanLX

Elder User

Joined: Mar 2003

Posts: 541

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From: Phoenix Az, by way of Fre

Quote:

Originally Posted by fordman428

i guess ill say it again, i was running my OWN trucks combo, my truck is not a 250, it has 15 in wheels, 25 in tires.

appologies.
just thought possibly the tire size math was fubar'd and maybe the rpm calc. was decieving as a result.
Was not meant to be antagonistic, but can see how is was.
Gotta stop type'n right before bed time.
appologies.

May 21, 2004 | 08:36 AM

#21

gtex

Lead Driver

Joined: Apr 2001

Posts: 6,175

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From: Texas

25" sounds short to me for any stock truck tire.

I calculate a 215-75r15 top be 27.7" tall using the claculator at 4l0.com

May 21, 2004 | 10:31 AM

#22

TNTsF-250

Senior User

Joined: Apr 2004

Posts: 172

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From: I live in Calif. near S.F

pace a car

Quote:

Originally Posted by jseim44

Does anyone know what kind of RPM's a 390 with a C6 and a D60 3.54 on 31x10.5 tires would be runnin at about 65? (It's in a '69 F-250 if that makes any difference) I know there is some long formula because i read it once but I was too young to care and forgot it

Thanks in advance!!!

I know ,get one of your buddys on the HY have him flag you at 65 and check what you readings are, or run your truck on a dyno.

May 21, 2004 | 11:29 AM

#23

jseim44

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Joined: Apr 2004

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From: St. Libory

hey guys thanks for all the info!!!!! that '69 is my dad's, but i think it would be a sweet rebuild project. it is currently used for hauling whatever crap we dont want to haul in our 97-98 F-150's