Rpm - The 1947 - Present Chevrolet & GMC Truck Message Board Network

74 stepside · 07-29-2012, 01:55 PM

Im currently getting my 74 stepside ready for the road. Decided to install a sbc instead of my bbc because I want to drive it daily. With 26" tall 295/50r15 tires in the rear and 400 trans does anyone have an idea of what kind of rpm Id be running at 70 mph with a 3.40 rear end gear??

INSIDIOUS '86 · 07-29-2012, 02:36 PM

I was at 3000 with a th350 and some 308's with 26 in tall tires

Either way you will want an overdrive
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thesickc10 · 07-29-2012, 03:11 PM

3076 rpm at 70 mph with 26" tire in 3rd gear

http://www.csgnetwork.com/multirpmcalc.html

74 stepside · 07-29-2012, 07:26 PM

Thats a cool web site for rpm calculating. Thanks.

INSIDIOUS '86 · 07-29-2012, 07:56 PM

Just remember that those numbers are static meaning they will not account for the slip that a torque converter supplys
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Firebirdjones · 07-29-2012, 10:53 PM

Stick a 28" tire on there and it will knock about ~2-300 rpm off that cruising speed. (And it fills out the wheel wells better

)

If you are really worried about it there are some taller tire options out there too. Nice thing about the trucks is that you actually have the room to do that if you choose.

07-29-2012, 01:55 PM	#1
74 stepside Registered User Join Date: Oct 2009 Location: SoCal Posts: 815	Rpm Im currently getting my 74 stepside ready for the road. Decided to install a sbc instead of my bbc because I want to drive it daily. With 26" tall 295/50r15 tires in the rear and 400 trans does anyone have an idea of what kind of rpm Id be running at 70 mph with a 3.40 rear end gear??

07-29-2012, 02:36 PM	#2
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Rpm I was at 3000 with a th350 and some 308's with 26 in tall tires Either way you will want an overdrive Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

07-29-2012, 03:11 PM	#3
thesickc10 Registered User Join Date: Sep 2010 Location: New Hope, PA Posts: 279	Re: Rpm 3076 rpm at 70 mph with 26" tire in 3rd gear http://www.csgnetwork.com/multirpmcalc.html __________________ 1985 c10 355 th350 (working on 4 speed conversion to super t10) 1979 camaro 358 super t10 2003 f250 superchip slp exhaust

07-29-2012, 07:26 PM	#4
74 stepside Registered User Join Date: Oct 2009 Location: SoCal Posts: 815	Re: Rpm Thats a cool web site for rpm calculating. Thanks.

07-29-2012, 07:56 PM	#5
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Rpm Just remember that those numbers are static meaning they will not account for the slip that a torque converter supplys Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

07-29-2012, 10:53 PM	#6
Firebirdjones Registered User Join Date: Oct 2009 Location: Prescott, Arizona Posts: 2,396	Re: Rpm Stick a 28" tire on there and it will knock about ~2-300 rpm off that cruising speed. (And it fills out the wheel wells better ) If you are really worried about it there are some taller tire options out there too. Nice thing about the trucks is that you actually have the room to do that if you choose.



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