GMC V6 305 question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DBear · 08-31-2011, 11:03 AM

Another question....can anyone give me some info on the GMC v6 motors in 60-66 trucks? Never had one, and wanted some info. Like mpg's, power, and performance and reliability? Thanks in advance.

athan66 · 08-31-2011, 11:19 AM

I've got one in my '66 GMC. It's big, heavy (~800lbs!), and has plenty of low end torque. Does not like to rev (I think it's limit is 3200-3400 rpm).

My truck has less than 30k miles on it and it runs very strong. Definitely has a unique sound to it and it does generate a fair amount of curiousity as many people have never heard of it, much less seen one.

As far as fuel economy, I average 10-12 MPG in my 2wd 3/4 ton with 4.10s and 2 speed automatic (power glide).

Nearly all the tune-up/consumable parts are available from NAPA. I have come across a few online sources that sell complete rebuild kits (pistons, rings, gaskets etc).

For more info on GMC V-6s in general, check out this website:

http://www.6066gmcguy.org/

DBear · 08-31-2011, 11:34 AM

thanks man....that is an awesome site for GMC's.

*HEI451* · 08-31-2011, 12:13 PM

I just put a 1965 305E V6 into my 1964 C30 flatbed dually, replacing the 292 inline 6 that the P/O blew the number 6 rod out of. Haven't got the exhaust system done yet, but have taken it around the block a couple of times, I LIKE IT.

Surfdaddy · 08-31-2011, 12:37 PM

Have a 305D in my 61 (2bbl carb, 152 hp when new) I put a petronics ignition and coil and it ran MUCH better. Mine has a Hyara-matic (4spd not overdrive) and the documented MPG since new has been about 10. I had a 63 and got the same MPG. Tons of torque not much hp. In town get a lot less MPG maybe 7. Mine is a 3/4 ton with a 410 posi and stock 28" tall tires. Great sound and very smooth running. Mine is all OEM with 77K miles on it. A few little oil leaks but what can I expect after 50 years without having the pan off.

64fleetside · 08-31-2011, 01:21 PM

They are big, heavy, slow, engines, nearly indestructible unless overspeeded. Designed to last a lifetime-the pistons are as big as coffee cans, crankshaft is too heavy to pick up. Built for longevity when gas was 19 cent/gal, so they like fuel. A true "truck" engine.

Surfdaddy · 08-31-2011, 07:37 PM

Engine size goes from 305 to something like a 472 I think all they change is the bore a little and the crank. Still, not too much in horsepower (I think max was something like 225 or so) but a ton of toruqe

DBear · 08-31-2011, 09:30 PM

Great info guys....I can't wait to pick my truck up on Saturday! I am gonna put new plugs and plug wires on it. It is missing 2 plug wires anyways. I have been looking at spark plugs at NAPA, and they have Autolites for it, with 3/4in and 3/8in reaches, does anyone know what reach to use.....I am figuring the 3/4in reach??????

KIC · 08-31-2011, 09:37 PM

Mine gets about 8mpg whether I'm going up hill, down hill, fast, slow, engine on, engine off. 8 MPG. it's a pig but reliable. It started after sitting 8 -10 years without any spark plugs in it.

KIC · 08-31-2011, 09:43 PM

Oh Yea...

GMC V-6 Engines
GMC Truck produced a unique 60° V6 engine from 1960 through 1978. The engine was available in 305, 351, 401 and 478-cubic-inch (5.0, 5.8, 6.6, and 7.8 L) versions. In late production there was also a 432-cubic-inch (7.1 L) version with enlarged crankshaft journals. GMC also made a 637-cubic-inch (10.4 L) 60° V8 with twin balance shafts using the same general layout as the 305. Finally, there was a 702-cubic-inch (11.5 L) "Twin Six" V12, which was basically two 351s placed end-to-end with a common block and crank. A Diesel version was called the ToroFlow.

305 -The 305-cubic-inch (5.0 L) 305 had a 4.25 in (108 mm) bore and 3.58 in stroke (90.9 mm). The 305 V6 was the standard pickup truck engine for GMC from 1960 to 1966, and was one of the first V6 engines produced by an American company.

DBear · 08-31-2011, 09:46 PM

Quote:

Originally Posted by KIC

Mine gets about 8mpg whether I'm going up hill, down hill, fast, slow, engine on, engine off. 8 MPG. it's a pig but reliable. It started after sitting 8 -10 years without any spark plugs in it.

that is funny stuff KIC......I was hoping for 20 miles per gallon. LOL. Maybe if I change gears and put 5 speed in it...Maybe!

neto · 08-31-2011, 11:27 PM

I just enjoy driving it and stop when I need gas. Drive behind truckers so at least 60 mph. So far my MPG has equaled a lot of fun.

KIC · 09-01-2011, 08:16 AM

Quote:

Originally Posted by DBear

that is funny stuff KIC......I was hoping for 20 miles per gallon. LOL. Maybe if I change gears and put 5 speed in it...Maybe!

The only 20 miles to the gallon you'd get with a V-6 would be with drinking beer.

jbgroby · 09-01-2011, 02:09 PM

Dbear,

Check my webshots link, I have just about everything you'd want to learn about from the ground up twice! Read hear for the reasons.

http://67-72chevytrucks.com/vboard/s...d.php?t=340519

Change the rearend from stock to 3.23 and use a 2 barrle carb setup I can get 17 MPG if I stay below 70. and 12-14 at 70+.

I don't believe there is anything you can do that I have not either done or considered.

Jake Groby

08-31-2011, 11:03 AM	#1
DBear Registered User Join Date: Nov 2008 Location: Rowlett, TX Posts: 867	GMC V6 305 question Another question....can anyone give me some info on the GMC v6 motors in 60-66 trucks? Never had one, and wanted some info. Like mpg's, power, and performance and reliability? Thanks in advance.

08-31-2011, 11:19 AM	#2
athan66 Registered User Join Date: Aug 2011 Location: Hudson, WI Posts: 27	Re: GMC V6 305 question I've got one in my '66 GMC. It's big, heavy (~800lbs!), and has plenty of low end torque. Does not like to rev (I think it's limit is 3200-3400 rpm). My truck has less than 30k miles on it and it runs very strong. Definitely has a unique sound to it and it does generate a fair amount of curiousity as many people have never heard of it, much less seen one. As far as fuel economy, I average 10-12 MPG in my 2wd 3/4 ton with 4.10s and 2 speed automatic (power glide). Nearly all the tune-up/consumable parts are available from NAPA. I have come across a few online sources that sell complete rebuild kits (pistons, rings, gaskets etc). For more info on GMC V-6s in general, check out this website: http://www.6066gmcguy.org/ Last edited by athan66; 08-31-2011 at 11:42 AM.

08-31-2011, 11:34 AM	#3
DBear Registered User Join Date: Nov 2008 Location: Rowlett, TX Posts: 867	Re: GMC V6 305 question thanks man....that is an awesome site for GMC's.

08-31-2011, 12:13 PM	#4
HEI451 Account Suspended Join Date: Mar 2011 Location: Yerington, Nevada Posts: 864	Re: GMC V6 305 question I just put a 1965 305E V6 into my 1964 C30 flatbed dually, replacing the 292 inline 6 that the P/O blew the number 6 rod out of. Haven't got the exhaust system done yet, but have taken it around the block a couple of times, I LIKE IT.

08-31-2011, 12:37 PM	#5
Surfdaddy Registered User Join Date: Jan 2011 Location: Newhall Ca. Posts: 463	Re: GMC V6 305 question Have a 305D in my 61 (2bbl carb, 152 hp when new) I put a petronics ignition and coil and it ran MUCH better. Mine has a Hyara-matic (4spd not overdrive) and the documented MPG since new has been about 10. I had a 63 and got the same MPG. Tons of torque not much hp. In town get a lot less MPG maybe 7. Mine is a 3/4 ton with a 410 posi and stock 28" tall tires. Great sound and very smooth running. Mine is all OEM with 77K miles on it. A few little oil leaks but what can I expect after 50 years without having the pan off. __________________ 1961 GMC. Start date 1/20/2011 Past projects: 1958 Fleetliner 14ft Runabout 1966 Caprice 2dr 1970 VW Squareback

08-31-2011, 01:21 PM	#6
64fleetside Registered User Join Date: Apr 2004 Location: arkieland Posts: 1,070	Re: GMC V6 305 question They are big, heavy, slow, engines, nearly indestructible unless overspeeded. Designed to last a lifetime-the pistons are as big as coffee cans, crankshaft is too heavy to pick up. Built for longevity when gas was 19 cent/gal, so they like fuel. A true "truck" engine.

08-31-2011, 07:37 PM	#7
Surfdaddy Registered User Join Date: Jan 2011 Location: Newhall Ca. Posts: 463	Re: GMC V6 305 question Engine size goes from 305 to something like a 472 I think all they change is the bore a little and the crank. Still, not too much in horsepower (I think max was something like 225 or so) but a ton of toruqe __________________ 1961 GMC. Start date 1/20/2011 Past projects: 1958 Fleetliner 14ft Runabout 1966 Caprice 2dr 1970 VW Squareback

08-31-2011, 09:30 PM	#8
DBear Registered User Join Date: Nov 2008 Location: Rowlett, TX Posts: 867	Re: GMC V6 305 question Great info guys....I can't wait to pick my truck up on Saturday! I am gonna put new plugs and plug wires on it. It is missing 2 plug wires anyways. I have been looking at spark plugs at NAPA, and they have Autolites for it, with 3/4in and 3/8in reaches, does anyone know what reach to use.....I am figuring the 3/4in reach??????

08-31-2011, 09:37 PM	#9
KIC 1960 GMC Burb Join Date: Jan 2008 Location: Arizona Posts: 385	Re: GMC V6 305 question Mine gets about 8mpg whether I'm going up hill, down hill, fast, slow, engine on, engine off. 8 MPG. it's a pig but reliable. It started after sitting 8 -10 years without any spark plugs in it. __________________ 1960 GMC Suburban 1/2 ton V-6 2nd generation original owner 60 Burb Build thread: http://67-72chevytrucks.com/vboard/s...=1960+Suburban 60 to 66 Burbs only Thread: http://67-72chevytrucks.com/vboard/s...ighlight=burbs 2003 Tahoe LT

08-31-2011, 09:43 PM	#10
KIC 1960 GMC Burb Join Date: Jan 2008 Location: Arizona Posts: 385	Re: GMC V6 305 question Oh Yea... GMC V-6 Engines GMC Truck produced a unique 60° V6 engine from 1960 through 1978. The engine was available in 305, 351, 401 and 478-cubic-inch (5.0, 5.8, 6.6, and 7.8 L) versions. In late production there was also a 432-cubic-inch (7.1 L) version with enlarged crankshaft journals. GMC also made a 637-cubic-inch (10.4 L) 60° V8 with twin balance shafts using the same general layout as the 305. Finally, there was a 702-cubic-inch (11.5 L) "Twin Six" V12, which was basically two 351s placed end-to-end with a common block and crank. A Diesel version was called the ToroFlow. 305 -The 305-cubic-inch (5.0 L) 305 had a 4.25 in (108 mm) bore and 3.58 in stroke (90.9 mm). The 305 V6 was the standard pickup truck engine for GMC from 1960 to 1966, and was one of the first V6 engines produced by an American company. __________________ 1960 GMC Suburban 1/2 ton V-6 2nd generation original owner 60 Burb Build thread: http://67-72chevytrucks.com/vboard/s...=1960+Suburban 60 to 66 Burbs only Thread: http://67-72chevytrucks.com/vboard/s...ighlight=burbs 2003 Tahoe LT

08-31-2011, 11:27 PM	#12
neto Registered User Join Date: Jan 2007 Location: Madera, California Posts: 291	Re: GMC V6 305 question I just enjoy driving it and stop when I need gas. Drive behind truckers so at least 60 mph. So far my MPG has equaled a lot of fun. Attached Images

09-01-2011, 02:09 PM	#14
jbgroby Registered User Join Date: Nov 2008 Location: Lacombe, LA Posts: 2,772	Re: GMC V6 305 question Dbear, Check my webshots link, I have just about everything you'd want to learn about from the ground up twice! Read hear for the reasons. http://67-72chevytrucks.com/vboard/s...d.php?t=340519 Change the rearend from stock to 3.23 and use a 2 barrle carb setup I can get 17 MPG if I stay below 70. and 12-14 at 70+. I don't believe there is anything you can do that I have not either done or considered. Jake Groby __________________ http://s1299.photobucket.com/user/jb...23904108567829



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