1966 GMC 3/4 gas mileage question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chimney chop · 04-24-2011, 10:00 PM

newb question here.

i'm looking into a 66 GMC 3/4 ton with a 350 engine, 700 automatic transmission.

about how many mp/gallon should i expect in the city?

oldblue1968chevy · 04-24-2011, 10:54 PM

depends on rear gears, in the city you may not be hitting the OD either//

jimmydean · 04-24-2011, 11:33 PM

How is the motor built? My C20 has a 327 and gets about 7mpg. I have an Edelbrock intake and carb with HEI I hope to install next week in hopes to improve mileage.

**Captainfab** · 04-25-2011, 12:03 AM

My '66 C20 used to get about 10 mpg. That was with a 327, 600 Holley, HEI, headers, etc. SM420 and 4.57 rear gears and 9.50x 16.5 tires. So depending on how that 350 is built and tuned, I would think that 14-16 should be doable. Of course there are other factors involved such as rear gears and tire size.

04-24-2011, 10:00 PM	#1
chimney chop Registered User Join Date: Apr 2011 Location: El Paso TX Posts: 58	1966 GMC 3/4 gas mileage question newb question here. i'm looking into a 66 GMC 3/4 ton with a 350 engine, 700 automatic transmission. about how many mp/gallon should i expect in the city? Last edited by chimney chop; 04-24-2011 at 10:00 PM.

04-24-2011, 10:54 PM	#2
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: 1966 GMC 3/4 gas mileage question depends on rear gears, in the city you may not be hitting the OD either// __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

04-24-2011, 11:33 PM	#3
jimmydean Registered User Join Date: May 2005 Location: Beaverton, OR Posts: 3,728	Re: 1966 GMC 3/4 gas mileage question How is the motor built? My C20 has a 327 and gets about 7mpg. I have an Edelbrock intake and carb with HEI I hope to install next week in hopes to improve mileage. __________________ New Project: 1966 LWB C20 Plans: 1/2 ton conversion Dropmember front Dropmember rear Corvette discs Restored raised bed http://67-72chevytrucks.com/vboard/s....php?p=4295210

04-25-2011, 12:03 AM	#4
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,250	Re: 1966 GMC 3/4 gas mileage question My '66 C20 used to get about 10 mpg. That was with a 327, 600 Holley, HEI, headers, etc. SM420 and 4.57 rear gears and 9.50x 16.5 tires. So depending on how that 350 is built and tuned, I would think that 14-16 should be doable. Of course there are other factors involved such as rear gears and tire size. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE



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