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#1 |
Registered User
Join Date: Jul 2013
Location: G.V. CA
Posts: 41
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straight six question
I have been considering putting a six and a 4 speed in my truck what I am wondering is what kind of mpg I could get out of it with that set up, its a 2wd shorty and I will be running 308 gears if that helps. Thanks in advance
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#2 |
Account Suspended
![]() Join Date: Oct 2012
Location: here
Posts: 2,408
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Re: straight six question
I'm runnin a 65 SBSS. 1971 Olds Rocket 250 I6. Currently running the peanut 3 speed and 3.73 rear. With the weber 2 barrel and the HEI ignition I pull an honest 18.4 mpg combined hwy/city every tank. Ocassionally 19.5 to almost 20 on the interstate staying at or below 65 mph.
Switching to a 5 speed this winter, expecting to see an additional 2 to 5 mpg. 308 might be a bit much for a six....pretty slow start but prolly great on highway...your final drive should still be 1 to 1 just like the peanut. (Mr. Langdon does not recommend less than about 3.50 rear gear with an overdrive manual gear box...so I'm stickin with my 3.73 out back.) |
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#3 | |
Registered User
Join Date: Jan 2013
Location: Columbia, SC
Posts: 1,927
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Re: straight six question
Quote:
If you use a Rochester B carb, an inline 230 or 250 and 3.08 gears I'd guess you'll get 15mpg or a tad better depending on how you drive and if any is highway or not. EDIT: Looks like he beat me to the punch!
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My 65 C10 build: www.lugnutz65chevystepside.weebly.com Want to know more about T5 transmissions? My website has a T5 Info Page and a Step by Step T5 rebuild. |
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#4 |
Account Suspended
![]() Join Date: Oct 2012
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Posts: 2,408
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Re: straight six question
If you can find a Rochester B that don't leak as much gas as flows thru it! HA!!!!!!
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#5 | |
Registered User
Join Date: Oct 2010
Location: Independence,KS
Posts: 1,477
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Re: straight six question
Quote:
But I am all about EFI now- so much easier and no adjustments required. ![]() |
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#6 |
Account Suspended
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Re: straight six question
Most recent trip to the Low Country netted an average mileage of 18.7ish at various speeds 60 to 70 mph....mostly around 60. Some city drivin in there. Trip back was durn close to 20 at about 19.6 mph, we had no city drivin on that pass.
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#7 |
Registered User
Join Date: Sep 2012
Location: Oregon
Posts: 3,303
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Re: straight six question
I have a worked over 250 in my daily. Lump ports, hei, z28, big cam , milled , balenced, cast headers, clifford and 390. I get 16 to 19.5 with a 700r4. And 3:73. It was worse with the 4spd and 3:08s. Tons of torque, good power great milage. Look up Tom at 12bolt.com and follow his direction. Problem is, you can build 3 or 4 small blocks for what you will have in the warmed up 6.
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#8 | |
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Posts: 2,408
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Re: straight six question
Quote:
![]() I could see mileage being worse with a 6 and the 308 rear. Trucks are heavy and bricklike and the motor is small. Pretty much seems you may have it lugging all the time with 308s. |
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#9 |
Post Whore
![]() Join Date: Mar 2013
Location: Southern Oregon
Posts: 10,384
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Re: straight six question
I have a 600 cfm edelbrock 4 barrel and headers and hei on my 292. Stock 4 speed and I believe 3.90 gear ratio with 30/9.50/15's for tires. At 2500 rpm I'm doing about 50-55(my speedo is junk) and I'm probably getting around 16. At that rpm I'm just touching the pedal and when I jam into it fuel milage goes to 4 mpg!!!
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1966 Chevy C10 "Project Two Tone" http://67-72chevytrucks.com/vboard/s...d.php?t=596643 1964 GMC "Crustine" semi-build:http://67-72chevytrucks.com/vboard/s...d.php?t=665056 My youtube channel. Username "Military Chevy": https://www.youtube.com/channel/UC_h...fzpcUXyK_5-uiw |
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