GMC engine - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bobs409 · 06-30-2002, 06:48 AM

Found a 67-72 GMC in the local junk yard and it has an engine I have never seen before. It has GMC on the valve covers and they are shaped like an "M". (not a 348 or 409) It is big.

What the heck is this thing? Anything worthy on it? It looks complete except carb.

68 Suburban · 06-30-2002, 07:16 AM

Sounds like a 305ci V-6. It also could have a 351ci V-6, but that was very rare in our trucks. These are high torque low rpm engines. They were only available in the GMC's

Here is a good link.
http://www.favorites.com/~jolly/305V6.htm

Patrick Sullivan · 06-30-2002, 08:51 AM

Wow, no kidding.. 280 pounds of torque at 1600 RPM for the 305. It's like a diesel without the diesel.. :p

Longhorn Man · 06-30-2002, 09:35 AM

It takes lots of abuse, or neglect...or jst a butt load of miles, to kill one of these motors.
Acording to the dope smokin old man, (the guy i bought my GMC off of) the original motor in my truck (305 V-6) died just shy of 400,000 miles, and he put another 100K on it after they put in the 400.
The V-6 was the base model motor on these trucks, I think 69 and older. You can tell if it is a V-6 truck by the vin...the second diget will be an M.

Rod · 07-01-2002, 12:00 AM

Found a 64 Buick special that had a V6 ... also had power steering... will it (PS) fit the gmc v6 ... Id grab it to sell it... I dont need it.
This is what the car looked like.

bobs409 · 07-01-2002, 06:24 AM

I'll have to check when I go back but it looked like an 8 cylinder to me. I've never seen a V-6 this big before! I'll have to count plugs next time.

68 Suburban · 07-01-2002, 06:35 AM

You are going to be in for a big suprise when you go to count the spark plugs

Longhorn Man · 07-01-2002, 07:29 AM

Yep, it is the big block of V-6's.

Looked something like this?

bobs409 · 07-02-2002, 06:35 AM

That's it! Monsterous.

I never thought to count plugs when I first saw it.

I get a kick out of the tiny carb and air cleaner.

I guess there's nothing of value to rescue then. Thought the valve covers looked cool though.

69gmcfleet · 07-02-2002, 07:04 PM

The 305 V-6 in my truck only lasted 100,000 miles.
Go figure!
It was a plow truck though.

Longhorn Man · 07-02-2002, 08:21 PM

Quote:

Originally posted by 69gmcfleet
The 305 V-6 in my truck only lasted 100,000 miles.

Wow, did they try to kill it? That's just wrong. Most were retired becouse the truck was falling apart around the engine.

69gmcfleet · 07-02-2002, 09:53 PM

The second owner of the truck, which is the guy who I bought it from, said the block cracked.
I am positive of the mileage because of the credibility of the first two owners and the great condition of the truck. It has minimal rocker and cab corner rust and everything else is still functional on the truck.

I like my 350 with mild cam though!

Super Chevy · 07-02-2002, 11:25 PM

it cracked because the previous owners neglected to add more antifreeze to the water/antifreeze combo and got below frezzing,thats what probably cracked your block

69gmcfleet · 07-04-2002, 10:53 AM

Yeah I am sure it was due to neglect by one of the previous owners.
I never even saw the motor. It was gone when i bought it.
But the front fender emblems still display V-6.
People always ask me why my V-6 sounds so mean!

06-30-2002, 06:48 AM	#1
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	GMC engine Found a 67-72 GMC in the local junk yard and it has an engine I have never seen before. It has GMC on the valve covers and they are shaped like an "M". (not a 348 or 409) It is big. What the heck is this thing? Anything worthy on it? It looks complete except carb. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

06-30-2002, 07:16 AM	#2
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	Sounds like a 305ci V-6. It also could have a 351ci V-6, but that was very rare in our trucks. These are high torque low rpm engines. They were only available in the GMC's Here is a good link. http://www.favorites.com/~jolly/305V6.htm __________________ Just sitting here contemplating contemplation. Last edited by 68 Suburban; 06-30-2002 at 07:18 AM.

06-30-2002, 08:51 AM	#3
Patrick Sullivan Transcendental Trucker Join Date: Dec 2001 Location: Rockaway Beach, OR Posts: 374	Wow, no kidding.. 280 pounds of torque at 1600 RPM for the 305. It's like a diesel without the diesel.. :p __________________ Patrick Sullivan \| sullivan@oregoncoast.com Rockaway Beach, Oregon 1972 Chevy Cheyenne C-20 1998 Dodge Dakota 4x4 So, fill to me the parting glass And drink a health whate'er befalls... Then gently rise and softly call Goodnight and joy be to you all!

07-01-2002, 12:00 AM	#5
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Found a 64 Buick special that had a V6 ... also had power steering... will it (PS) fit the gmc v6 ... Id grab it to sell it... I dont need it. This is what the car looked like. Attached Images __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

07-01-2002, 06:24 AM	#6
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	I'll have to check when I go back but it looked like an 8 cylinder to me. I've never seen a V-6 this big before! I'll have to count plugs next time. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

06-30-2002, 09:35 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	It takes lots of abuse, or neglect...or jst a butt load of miles, to kill one of these motors. Acording to the dope smokin old man, (the guy i bought my GMC off of) the original motor in my truck (305 V-6) died just shy of 400,000 miles, and he put another 100K on it after they put in the 400. The V-6 was the base model motor on these trucks, I think 69 and older. You can tell if it is a V-6 truck by the vin...the second diget will be an M.

07-01-2002, 06:35 AM	#7
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	You are going to be in for a big suprise when you go to count the spark plugs __________________ Just sitting here contemplating contemplation.

07-01-2002, 07:29 AM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Yep, it is the big block of V-6's. Looked something like this?

07-02-2002, 06:35 AM	#9
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	That's it! Monsterous. I never thought to count plugs when I first saw it. I get a kick out of the tiny carb and air cleaner. I guess there's nothing of value to rescue then. Thought the valve covers looked cool though. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

07-02-2002, 07:04 PM	#10
69gmcfleet Registered User Join Date: Apr 2000 Location: Oneonta, NY, US Posts: 103	The 305 V-6 in my truck only lasted 100,000 miles. Go figure! It was a plow truck though. __________________ Jeff '69 GMC K2500 LWB, '74 350/SM465/Rockwell T-221, cnD44/ffD60, 3.73 gears, 31" BFG's (originally had 305ci V-6) '05 VW golf '84 HD Sportster XLX '68 GMC K2500 parts beast

07-02-2002, 09:53 PM	#12
69gmcfleet Registered User Join Date: Apr 2000 Location: Oneonta, NY, US Posts: 103	The second owner of the truck, which is the guy who I bought it from, said the block cracked. I am positive of the mileage because of the credibility of the first two owners and the great condition of the truck. It has minimal rocker and cab corner rust and everything else is still functional on the truck. I like my 350 with mild cam though! __________________ Jeff '69 GMC K2500 LWB, '74 350/SM465/Rockwell T-221, cnD44/ffD60, 3.73 gears, 31" BFG's (originally had 305ci V-6) '05 VW golf '84 HD Sportster XLX '68 GMC K2500 parts beast

07-02-2002, 11:25 PM	#13
Super Chevy Registered User Join Date: Feb 2001 Location: Ohio Posts: 1,025	it cracked because the previous owners neglected to add more antifreeze to the water/antifreeze combo and got below frezzing,thats what probably cracked your block

07-04-2002, 10:53 AM	#14
69gmcfleet Registered User Join Date: Apr 2000 Location: Oneonta, NY, US Posts: 103	Yeah I am sure it was due to neglect by one of the previous owners. I never even saw the motor. It was gone when i bought it. But the front fender emblems still display V-6. People always ask me why my V-6 sounds so mean! __________________ Jeff '69 GMC K2500 LWB, '74 350/SM465/Rockwell T-221, cnD44/ffD60, 3.73 gears, 31" BFG's (originally had 305ci V-6) '05 VW golf '84 HD Sportster XLX '68 GMC K2500 parts beast



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