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12-20-2011, 08:31 AM
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#1 |
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Registered User
Join Date: Jun 2010
Location: Parsons, KS
Posts: 36
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250 I-6 cruise RPM?
Restoring a 72 GMC 1500 2wd for my dad. 250 i-6 (planning on fuel injection and mild cam). I have an s10 t5 for it, i believe its .86 OD? Its goin to be DD so Id like to build it so it will cruise 65-70mph easily. Can anyone tell me what a safe cruise rpm for the little 6 banger is? Need to know so i can choose tire size and gear ratio!
Its pretty low geared as is, sm465 and 235/75R15s, 50 mph is about the top end of things! Thanks JR |
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12-20-2011, 10:18 AM
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#2 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: 250 I-6 cruise RPM?
if it'll only do 50, then there is something major wrong with that engine.
That truck should have a 3.73 gear, which'll move the truck to over 100 MPH. A t 5 with that ratio should work great. |
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12-20-2011, 06:33 PM
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#3 |
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Registered User
Join Date: Jun 2010
Location: Parsons, KS
Posts: 36
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Re: 250 I-6 cruise RPM?
itll go 85+ but at 50mph its wound way tight! Thanks for the response, much appreciated!
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12-20-2011, 06:41 PM
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#4 |
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Registered User
Join Date: May 2010
Location: Hillsboro, Oregon 97123
Posts: 1,300
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Re: 250 I-6 cruise RPM?
Im not going to be much help Im sure but my 250 is running 235 75 15 rear tires and 3.72 gears....and I run Very close to 2500-2600 RPM at 55-57 MPH
I could use a Over drive ...maybe a 700r4..............Someday
__________________
Measure with a yard stick Mark with Chalk Cut with a torch  Built it yourself, don't count on others to to do it for you or with you. It will never get done |
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12-21-2011, 08:25 AM
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#5 |
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Registered User
Join Date: Jun 2010
Location: Parsons, KS
Posts: 36
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Re: 250 I-6 cruise RPM?
Had a 74 gmc with a 250, put T5 in it and it was the best mod i ever did, other then the speedo didnt work. But i cant remember what gear ratio it had!
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