V-6 ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**uncle** · 01-22-2006, 07:32 PM

How can you tell the difference from 305 and 351?

teeitup · 01-22-2006, 08:30 PM

I was told once, I think, there is numbers on front of block, one has 305 stamped the other has 351, I got a block over at work, I'll try to look at it tomorrow.

**uncle** · 01-22-2006, 09:08 PM

Thanks.

JAKES 68GMC · 01-22-2006, 10:18 PM

If its a 351 Magnum or any magnum, it will have a trapezoid base where the carb bolts to the intake. 305E and 351E will have a rectangular pattern, In front of the right head, the casting number is right there. First 3 numbers are the engine displacement.

TP from Cntl PA · 01-22-2006, 10:22 PM

Who cares

............IMO they were both great engines

The Mag's were supposed to be better, haven't got my hands on one yet. I know that little 305 in my one ton will run the balls off V-8's 50 cubes larger with a load. Nothing like pulling a hill and the engine just won't quit!!!!!!!!!!!!

Fred T · 01-22-2006, 10:31 PM

http://www.6066gmcguy.org/EngineData.htm

**Bob B.** · 01-23-2006, 12:09 AM

The numbers are stamped on the block deck surface just ahead of the right cylinder head. 351's were only used in pickups from 1966-68.

JAKES 68GMC · 01-23-2006, 07:15 PM

What are the average MPG and cruising speeds for the 305E? My truck ain't registered so we cant really tell what cruising speed is. The carb is all rusty and gummed up and dirty, so you can just about see the gas come outta the tailpipes. Runs like a top though.

**Bob B.** · 01-23-2006, 07:23 PM

They like fuel. A lot of fuel. But, they run good on the cheap stuff, so that helps a bit. My 351 would only get about 10 m.p.g., before I took it apart. These engines were designed to work hard at low r.p.m.'s, and 4000 is about the limit. How fast you truck will go depends on the rear axle gearing.

JAKES 68GMC · 01-23-2006, 07:39 PM

I think it has 4.10's.

chevy_fatman · 01-23-2006, 08:21 PM

I think my Longhorn also has 4.10 in the back and that motor is pretty wound up when going 60 mph, I'm afraid to go faster than that, so I think 60 is max and that may be pushing it, as said before these were working trucks, not highway cruisers, maybe a 5 speed tranny could help in the open highway a bit.

JAKES 68GMC · 01-23-2006, 08:27 PM

3.55 rears, or heck, even 3.73s wouldnt hurt the truck a bit. But to change the rear gears, that wouldn't be original, so I couldn't possibly do that. (dad's rule) The 305 seems to accelerate better lugging anyways. What size tires are you running? Mine are 32 inches in diameter. I've read in some places that 60-66 one-tons with 351E's would do 90 no problem. I may raise the B.S. flag for that though.

**uncle** · 01-23-2006, 08:46 PM

Thanks for all the response. I just bought a 68 GMC 1 ton with a v-6 ( My 1st one obviously) and was curious what size it is. I drove the truck a little, but seems to be geared pretty low. I think 60 would definitely max this one out. Mine has 17.5 inch wheels. Thanks again Tim.

TP from Cntl PA · 01-23-2006, 09:30 PM

Jake, they like a lug better being wound up

JAKES 68GMC · 01-23-2006, 10:02 PM

I figured that out. What really boggles me is that it accelerate faster lugging in 3rd gear than giving it to her in 2nd

I have an 84mph potential with 33's (or 285's). Thats fast enough for me.

I plan on a Holley 500 2bbl, 3 inch dual exhaust, and maybe a Pertronix Ignitor to replace the points. That would wake it up some.

chevy_fatman · 01-23-2006, 11:59 PM

My truck still has the original wheels, I'm thinking 31 or 32in diameter.

When you get that Holly on there let me know how it works out for you, I couldn't make it work on mine, I heard somewhere that I had to change the 305 intake to the 351 one to make it work, never did, but I do know where '71 GMC 1 ton with a 351 is at, so is all about whenever I get ready, darn! I just remembered that I need a shroud and I didn't even looked at that truck for it this past weekend doh!

JAKES 68GMC · 01-25-2006, 06:02 PM

Quote:

Originally Posted by chevy_fatman

When you get that Holly on there let me know how it works out for you, I couldn't make it work on mine, I heard somewhere that I had to change the 305 intake to the 351 one to make it work, never did.:

Hmmmm. Jolly's 60-66 GMC site can tell you about everything you need to know. All you need (to my knowledge) is a rochester 4 bolt 2 bbl. adapter to a large Holley 2 bbl. and adapter. 17 or 18 bucks from Jegs. Everyone on the 60-66 yahoo board swear by the 500 holley. I wonder what they would do with a 600 Edelbrock

BobS · 01-25-2006, 08:36 PM

The adapter for the Holley 2 bbl will only work on the 305 manifold. The 351E uses a carb with a trapezoid bolt arrangement. There used to be an adapter made for that application but it is no longer available. If you're looking for one, Pete Chronis on the 60-66 board is having some made, he may be able to increase the order.

Bob

chevy_fatman · 01-26-2006, 06:56 PM

Quote:

Originally Posted by JAKES 68GMC

Hmmmm. Jolly's 60-66 GMC site can tell you about everything you need to know. All you need (to my knowledge) is a rochester 4 bolt 2 bbl. adapter to a large Holley 2 bbl. and adapter. 17 or 18 bucks from Jegs. Everyone on the 60-66 yahoo board swear by the 500 holley. I wonder what they would do with a 600 Edelbrock

BobS just said what I was talking about, that's why mine didn't work out the way I wanted.

Quote:

Originally Posted by BobS

The adapter for the Holley 2 bbl will only work on the 305 manifold. The 351E uses a carb with a trapezoid bolt arrangement. There used to be an adapter made for that application but it is no longer available. If you're looking for one, Pete Chronis on the 60-66 board is having some made, he may be able to increase the order.

Bob

Fred T · 01-24-2006, 02:19 AM

If you want that V6 to last, keep the highway revs down. If you ever see how big the counterweights on the crank are, you will understand why.

**uncle** · 01-24-2006, 05:56 PM

I found it today. It's a 305. Thanks again.

**special-K** · 01-24-2006, 09:07 PM

The V6s don`t really need to be woken up.They`re just strokers, built for bottom end power and lowerrpm operation.O/d will get it cruising.

JAKES 68GMC · 01-24-2006, 09:46 PM

Well, I need something to brag up about the engine performance-wise. I need a carb regardless. Im going to try an make a homebuilt 4bbl intake this spring, just for fun

I know 3.55s would make this thing really scoot, but since it is an "odd" truck, I can't modify much of it. My dad told me so

I did the calculations online, and 54.98736567423748234698253478956mph or something is my cruising speed at 2300rpm in 4th with 33" tires.

So Sammy Hagar, I CAN DRIVE 55!!!!!!!! HAHA!!!

TP from Cntl PA · 01-24-2006, 09:53 PM

Quote:

Originally Posted by JAKES 68GMC

Well, I need something to brag up about the engine performance-wise.

Don't worry yourself.........They will make a SBC look like an A$$ on a hard pull(Been there, done that). They were built for truck use, and by darn they work good at it. If I had an NV4500 behind the one in my 1-ton it would be the "Perfect" truck. OD and a syncro on the "Basement" gear would be nice, because the clutch is stiffer than one in a 379 Pete

chevy_fatman · 01-24-2006, 09:53 PM

BTW, try getting parts for your motor at your local auto parts, they'll swear those motors don't exist

01-22-2006, 07:32 PM	#1
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,286	V-6 ? How can you tell the difference from 305 and 351?

01-22-2006, 08:30 PM	#2
teeitup Just like to part out trucks!! Join Date: Nov 2001 Location: Meriden, Ks-North of Topeka 10 miles Posts: 27,396	Re: V-6 ? I was told once, I think, there is numbers on front of block, one has 305 stamped the other has 351, I got a block over at work, I'll try to look at it tomorrow. __________________ 67 Chev swb stepside 4x4 283 4 speed SOLD 72 blazer 4x4 4 speed Cheyenne 72 GMC swb 4x4 fleet 4 speed, original paint 1958 Cameo (one of 1405 built, it was my dads) 2020 chevy Apex 4x4 crew cab 1969 Z28 with the 302 1980 chevy swb 4x4 1964 chevell Malibu SS 1976 K20, sold new originally out of my dads chevy dealership Members that I've met, over 200 probably closer to 300 in the 12 years I've been on this site, everyone I met "It was a pleasure"

01-22-2006, 09:08 PM	#3
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,286	Re: V-6 ? Thanks.

01-22-2006, 10:18 PM	#4
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? If its a 351 Magnum or any magnum, it will have a trapezoid base where the carb bolts to the intake. 305E and 351E will have a rectangular pattern, In front of the right head, the casting number is right there. First 3 numbers are the engine displacement.

01-22-2006, 10:22 PM	#5
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Re: V-6 ? Who cares ............IMO they were both great engines The Mag's were supposed to be better, haven't got my hands on one yet. I know that little 305 in my one ton will run the balls off V-8's 50 cubes larger with a load. Nothing like pulling a hill and the engine just won't quit!!!!!!!!!!!! __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

01-22-2006, 10:31 PM	#6
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: V-6 ? http://www.6066gmcguy.org/EngineData.htm __________________ Fred There is no such thing as too much cam...just not enough engine.

01-23-2006, 12:09 AM	#7
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,321	Re: V-6 ? The numbers are stamped on the block deck surface just ahead of the right cylinder head. 351's were only used in pickups from 1966-68. __________________ 1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90.

01-23-2006, 07:15 PM	#8
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? What are the average MPG and cruising speeds for the 305E? My truck ain't registered so we cant really tell what cruising speed is. The carb is all rusty and gummed up and dirty, so you can just about see the gas come outta the tailpipes. Runs like a top though.

01-23-2006, 07:23 PM	#9
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,321	Re: V-6 ? They like fuel. A lot of fuel. But, they run good on the cheap stuff, so that helps a bit. My 351 would only get about 10 m.p.g., before I took it apart. These engines were designed to work hard at low r.p.m.'s, and 4000 is about the limit. How fast you truck will go depends on the rear axle gearing. __________________ 1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90.

01-23-2006, 07:39 PM	#10
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? I think it has 4.10's.

01-23-2006, 08:21 PM	#11
chevy_fatman Where's my beer? Join Date: Aug 2002 Location: I live in the state of denial.... Posts: 5,621	Re: V-6 ? I think my Longhorn also has 4.10 in the back and that motor is pretty wound up when going 60 mph, I'm afraid to go faster than that, so I think 60 is max and that may be pushing it, as said before these were working trucks, not highway cruisers, maybe a 5 speed tranny could help in the open highway a bit. __________________ Paul How do you make the invisible, visible?.........You take it away. Last edited by chevy_fatman; 01-23-2006 at 08:23 PM.

01-23-2006, 08:27 PM	#12
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? 3.55 rears, or heck, even 3.73s wouldnt hurt the truck a bit. But to change the rear gears, that wouldn't be original, so I couldn't possibly do that. (dad's rule) The 305 seems to accelerate better lugging anyways. What size tires are you running? Mine are 32 inches in diameter. I've read in some places that 60-66 one-tons with 351E's would do 90 no problem. I may raise the B.S. flag for that though. Last edited by JAKES 68GMC; 01-23-2006 at 08:30 PM.

01-23-2006, 08:46 PM	#13
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,286	Re: V-6 ? Thanks for all the response. I just bought a 68 GMC 1 ton with a v-6 ( My 1st one obviously) and was curious what size it is. I drove the truck a little, but seems to be geared pretty low. I think 60 would definitely max this one out. Mine has 17.5 inch wheels. Thanks again Tim.

01-23-2006, 09:30 PM	#14
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Re: V-6 ? Jake, they like a lug better being wound up __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

01-23-2006, 10:02 PM	#15
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? I figured that out. What really boggles me is that it accelerate faster lugging in 3rd gear than giving it to her in 2nd I have an 84mph potential with 33's (or 285's). Thats fast enough for me. I plan on a Holley 500 2bbl, 3 inch dual exhaust, and maybe a Pertronix Ignitor to replace the points. That would wake it up some. Last edited by JAKES 68GMC; 01-23-2006 at 10:06 PM.



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01-23-2006, 11:59 PM	#16
chevy_fatman Where's my beer? Join Date: Aug 2002 Location: I live in the state of denial.... Posts: 5,621	Re: V-6 ? My truck still has the original wheels, I'm thinking 31 or 32in diameter. When you get that Holly on there let me know how it works out for you, I couldn't make it work on mine, I heard somewhere that I had to change the 305 intake to the 351 one to make it work, never did, but I do know where '71 GMC 1 ton with a 351 is at, so is all about whenever I get ready, darn! I just remembered that I need a shroud and I didn't even looked at that truck for it this past weekend doh! __________________ Paul How do you make the invisible, visible?.........You take it away.

01-25-2006, 08:36 PM	#18
BobS Senior Member Join Date: May 2001 Location: West Central Minnesota Posts: 568	Re: V-6 ? The adapter for the Holley 2 bbl will only work on the 305 manifold. The 351E uses a carb with a trapezoid bolt arrangement. There used to be an adapter made for that application but it is no longer available. If you're looking for one, Pete Chronis on the 60-66 board is having some made, he may be able to increase the order. Bob __________________ V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel

01-24-2006, 02:19 AM	#20
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: V-6 ? If you want that V6 to last, keep the highway revs down. If you ever see how big the counterweights on the crank are, you will understand why. __________________ Fred There is no such thing as too much cam...just not enough engine.

01-24-2006, 05:56 PM	#21
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,286	Re: V-6 ? I found it today. It's a 305. Thanks again.

01-24-2006, 09:07 PM	#22
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,861	Re: V-6 ? The V6s don`t really need to be woken up.They`re just strokers, built for bottom end power and lowerrpm operation.O/d will get it cruising. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

01-24-2006, 09:46 PM	#23
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,212	Re: V-6 ? Well, I need something to brag up about the engine performance-wise. I need a carb regardless. Im going to try an make a homebuilt 4bbl intake this spring, just for fun I know 3.55s would make this thing really scoot, but since it is an "odd" truck, I can't modify much of it. My dad told me so I did the calculations online, and 54.98736567423748234698253478956mph or something is my cruising speed at 2300rpm in 4th with 33" tires. So Sammy Hagar, I CAN DRIVE 55!!!!!!!! HAHA!!!

01-24-2006, 09:53 PM	#25
chevy_fatman Where's my beer? Join Date: Aug 2002 Location: I live in the state of denial.... Posts: 5,621	Re: V-6 ? BTW, try getting parts for your motor at your local auto parts, they'll swear those motors don't exist

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