1967 GMC V6 305 cu in...

[Loose Screw]

So I'm at the Cars and Coffee and I'm talking to 2 guys that have Super nice vehicles, I mean Beautiful. One has a Chevelle (yes, an SS 396) and the other guy has a '71 with a '67 front C10......I'm not in my truck.....

Yeah, so I'm talkin to the guy with the Chevelle tellin him that in 1967 C10 came with a small or big window and also the 1500s still could be had with that V6. Boy, Both Chevelle guy and '71 guy were all over me sayin I didn't know what I was talkin about...I did just leave it alone though...

and just a little side note I had a '66 with a V6 when I was a teenager and I had a 307 '68 after that...I Love old Chevy trucks, just don't tell a GMC guy that, he'll correct you right away...Heck, even a purest will correct you calling a non CST a CST (era) a "CST"...and don't even say that to a 1500 guy!

[54blackhornet]

Tell them to pound sand ! I am sure he doesn’t know about this either.

[Getter-Done]

Yeah,
Just smile and Nod your head sideways.

I am on one group on FB and there is some real Winners on there.

[Loose Screw]

Ha! I looked at my post above again at where I typed about "1500s and CSTs" and how to correctly refer to them, kind of reminds me of that pronoun bs going on in some people's heads right now.....

[truckster]

Most people don't even know the 305V6 ever existed. It was a fun motor. Not much speed, but gobs of torque, and a unique sound running through glasspacks.

['68OrangeSunshine]

In MY '67 you could order a C/10 with a 230, even. Or a 292. And I guess a C/1500 with a V6 at the GMC dealers.
A Marine buddy used to have a '68 GMC C/3500 [one ton] Flatbed with the big V6. 351?

I became a GMC owner in 1995 when I bought a '71 GMC Jimmy ''Custom'' K/1500. [Not a K/750] Both Blazers and Jimmys were all built on the St Louis line, 1970 and '71. Flint Mich joined in on the Blazers in MY 1972. [And Jimmys, too -- I guess.]

Funny how some people will defend their ignorance.

[kwmech]

My Dad had a 69 GMC 3/4 ton with the 351 V6. Torque monster is an understatement, it also loved drinking fuel. I think we got maybe 9 or 10 mpg

[Sheepdip]

Originally Posted by kwmech

My Dad had a 69 GMC 3/4 ton with the 351 V6. Torque monster is an understatement, it also loved drinking fuel. I think we got maybe 9 or 10 mpg

Outfit I worked for had big 66 GMC dump truck that pulled a trailer with a backhoe, it had a big 400 cu in V6 in it, slow as molasses in January but lots of torque. Always got there and back....slowly.

[Bob B.]

I have been told on several occasions my truck doesn't exist.

[Loose Screw]

Originally Posted by Bob B.

I have been told on several occasions my truck doesn't exist.

351? Cleveland or Windsor?

[54blackhornet]

My grandfather worked for GM in the NYC corporate headquarters for 37 years. He told me that the V6 engine design was the most over engineered engine GM ever built for a light duty vehicle…

[Bob B.]

One of the reasons it was so overbuilt was that they made a diesel version as well:

https://www.dieselworldmag.com/diese...nes/toro-flow/

[factorystock]

Question for Bob B. Is there a way to identify the heavy duty valve options on the 305 V6 externally? Assuming there is no build sheet. This chart is for the pickup, not the larger trucks with bigger 351 401 478 jobs.

['68OrangeSunshine]

Originally Posted by Loose Screw

351? Cleveland or Windsor?

The 351 Cleveland, and 351 Windsor were Ford V8s. The former a big block, built with small block parts. Not a Ford guy, so I don't know much about it.

But oddly, GMC did also produce a 351C, 351E and 351M in V6 form. Don't know where they made them. Flint or Pontiac MI would be my guess.

[Rods]

Here’s one i have for proof………beast engine but not so great on fuel milage.

[truckster]

It's always fun when someone who's never seen one before looks for the spark plugs.

[Bob B.]

Originally Posted by factorystock

Question for Bob B. Is there a way to identify the heavy duty valve options on the 305 V6 externally? Assuming there is no build sheet. This chart is for the pickup, not the larger trucks with bigger 351 401 478 jobs.

I have wondered that myself. I have a 1967 'Pleasure Trucks' brochure and it shows the 305E heavy duty valve and rotator option, but it is not listed in the regular 1967 light duty brochure. I can tell you for certain the 351E had the heavy duty valves, seats, and rotators standard as I saw my engine had those features when I rebuilt it, and it had never been apart. The 1967 Data Book shows heavy duty valves and rotators for the 305E engine as R.P.O. K71, a $24.00 option for all CM light trucks. And of course K71 would show on the SPID label and build sheet. But your question is what abouth the engine itself? I would assume there would be some code stamped into the block denoting K71 where the engine serial number is (like Chevy did for years with those 3 letter codes) but I don't know for sure. Engines had an information card attached to them from the engine plant for quick identification on the assembly line as you can see in some of the plant photos that have been posted here in the past. Those cards however were thrown away before the truck rolled off the line. That having been said, if the truck doesn't have a SPID or build sheet the surest way to find out if it has K71 is to pull off a valve cover. It's easy to see the valve rotators, they sit between the bottom of the valve spring and the head.

[Loose Screw]

Originally Posted by '68OrangeSunshine

The 351 Cleveland, and 351 Windsor were Ford V8s. The former a big block, built with small block parts. Not a Ford guy, so I don't know much about it.

But oddly, GMC did also produce a 351C, 351E and 351M in V6 form. Don't know where they made them. Flint or Pontiac MI would be my guess.

Yeah, I know, I just remember many years ago on another forum about the discussion with the young man counter clerk arguing with the old guy when the clerk asked "make, model, motor" and the clerk told the guy "you mean 350"....

[truckster]

Originally Posted by Loose Screw

Yeah, I know, I just remember many years ago on another forum about the discussion with the young man counter clerk arguing with the old guy when the clerk asked "make, model, motor" and the clerk told the guy "you mean 350"....

That's not surprising. I went into NAPA and asked for spark plugs for my 5.3. The guy behind the counter asked me if it was gas or diesel...

['68OrangeSunshine]

Originally Posted by Loose Screw

Yeah, I know, I just remember many years ago on another forum about the discussion with the young man counter clerk arguing with the old guy when the clerk asked "make, model, motor" and the clerk told the guy "you mean 350"....

For that numerological reason, the L6 Community calls a 292 [RPO L25] Block bored out to .060-over, a ''301,'' not a 300.
[A 292 at .030-over is 296 CuIn.]
The Ford L6 300 is a reverse-engineered 292 copy. [Or is it I-6 in Fordish? IDK. Don't speak it.]
They came out with it in 1965. The L25 292 came out in 1963. Enough time to buy one, take it apart, and copy it. The 300 Ford has its Carb, intake and exhaust on the Passenger side, and the distributor on the driver side. Pure ''reverse'' engineering.

[factorystock]

Originally Posted by Bob B.

the surest way to find out if it has K71 is to pull off a valve cover.

Thanks Bob. I was hoping there was a less evasive way. Was thinking maybe the engine had dual fanbelts or larger air cleaner to distinguish it from the standard duty V6.

[factorystock]

Originally Posted by '68OrangeSunshine

The Ford L6 300 is a reverse-engineered 292 copy. [Or is it I-6 in Fordish? IDK. Don't speak it.]
They came out with it in 1965. The L25 292 came out in 1963. Enough time to buy one, take it apart, and copy it. The 300 Ford has its Carb, intake and exhaust on the Passenger side, and the distributor on the driver side. Pure ''reverse'' engineering.

Correct. The thing about the 300, it was a much more popular engine than the 292. The smaller Ford 240 was discontinued in '74, making the 300 the only straight 6 in the line up. Chevy kept both the 250 and 292, not many 292 are out there, most 1/2 tons had the 250's and 3/4 tons usually came with V8's.

['68OrangeSunshine]

Originally Posted by factorystock

Correct. The thing about the 300, it was a much more popular engine than the 292. The smaller Ford 240 was discontinued in '74, making the 300 the only straight 6 in the line up. Chevy kept both the 250 and 292, not many 292 are out there, most 1/2 tons had the 250's and 3/4 tons usually came with V8's.

I have three 292s. One came with my '68 C/10 Stepside -- ordered by the original buyer. [Probably CalTrans or the SP -- Orange fleet truck]. I rebuilt another junkyard block at MCAS Yuma in 1977. [Building an engine was away of relieving boredom in a small hot town in the summer.] That L6 block ran til 2002. 250,000 miles. I rebuilt the OE block in 2005. That's on duty now.
Along the way I picked up another MY '63 292 core from Warrens69GMC who was working at a Checker Auto in Tucson.
When these trucks were the current product, GM dealers pushed V8s and Automatic transmissions hard. I have never seen a Blazer or Jimmy with a Factory L25 292.
I think the fact that the L25 requires a special diagonal crossmember in the 4X4s was one stumbling block. One parts counter guy at the Chevy dealer's said ''the 292 was Chevy's best kept secret.''
It's a very strong engine, with surplus torque that weighs 100 lbs less than an SBC. My 292 with modifications and aftermarket equipment outperforms the 350 crate motor in my '71 Jimmy.

[Bob B.]

The Ford 240 and 300 heads have alternating valve positions with individual ports, compared with the Chevy 6's siamesed intake ports. The center exhaust ports of the Chevy are also paired. The Chevy straight 6's use a number of 'Small Block' V-8 parts including pistons, valves, and rocker arms. The Ford 240 and 300 borrow some parts from the Windsor and FE V-8's. Cylinder head notwithstanding, I always thought the 292 was a better engine than the 300 because of its tall deck block and much better connecting rod ratio. The oiling system is better as well (Ford feeds the cam bearings before the mains). The 300 is something of a mythical engine among Ford fans (it is one of the better Ford engines no question) but I think the 292 was tougher and pulled harder at low r.p.m.'s.

The GMC V-6 was something else entirely, a purpose built heavy duty commercial engine that compares to the International Harvester V-8's and Ford Super Duty V-8's.

[factorystock]

Originally Posted by Rods

Here’s one i have for proof………beast engine but not so great on fuel milage.

GMC V6 1/2 tons came with a 3.07 rear standard, would think it would do ok in the gas mileage dept. '67 Chevy came with a 3.73 standard.