Ever hear this one

jwhoss76

jwhoss76

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Wonder if anyone else has heard this one. I have heard this many, many times from several different people "General motors built a 305 inline six that was used in medium and heavy trucks" Funny thing is it is not listed in the Fel-Pro Gasket catalog nor is it listed in any other parts catalog, at any parts store in my area. Kinda funny huh?
 
I know of two 305's that GM built. V6 GMC and V8 Chevy.

GMC has a 302 Inline but that's' about as much as I know.

Ctown
 
Never heard of a GMC 305 I6, though I suppose its possible there was one. Probably an industrial motor. There was a 302 I6, there's still guys who race with them & some have 12 port, cross-flow heads. The 228/248(?)/270/302 GMC I6's were made around the same time as the chev 216/235/261, though I don't think that anything interchanges.
There's a 305 v8 which I've heard a lot of chevy guys say they didn't like & a 305 v6. The v6 was actually an indutrial motor & a half v12. If you ever have the chance to look at one of these engines you can see that you'd bolt 2 blocks together, put a different crank & cam in & end up with a v12. Look carefully at some early '60s GMC 1/2 & 3/4 (?) ton trucks & you'll see a v6 symbol on the truck. The motor looks like a big block & the spark plugs go in on the intake side. Never really fooled with one, but a few friends have. No power, but the damn thing runs forever. Hope this helps. Take care,
Edwin
 
Hey, '76,

Give a call to Dick Larrowe & Sons down in Sandy, OR, 503-668-4096. They could answer any questions you might have about these motors.

Later, Kinky6.
 
If you look at the GMC 305-351 V6. You will see a 60 degree block with a huge bore and short stroke. The bottom end was strong as hell and they even lightened the valve train by raising the cam.

The engine was never developed for horse power and was a little ahead of its time. With some better heads and a diet, it could have been a contender. But with no after market support it had no chance.

The same can be said for the Mercruiser 195. It is half of a Ford 460 with an alloy block and all big block parts. I wieghs about the same as a Pinto motor and packs a punch. But it doesn't have any after market support. There have been a few put in dragsters with an SVO head and Hilborn injectors.
Love to see one in a Pinto!

John
 
:unsure: A 302 I6 never heard of that one! I've never seen the 305 V6 but I have heard of that one.Thanks for the feedback. I appretiate it.
 
the 305/355 Chev V6 appeared in pickups and medium sized trucks in the early '60s. It was a high-torque, low-speed engine designed primarily for trucks and had no high-performance potential. A diesel version, the 6V53 was also developed for mid-sized trucks at the same time.
 
Back in pre-history times when I was a school bus fleet mechanic and worked on buses and school cars and vans, I took care of a '65 GMC Suburban school van with 4 wheel drive and the infamous 305 V6. The engine did indeed look like a BBC but I don't recall doing anything but routine mainteenance on it. I don't think GM ever made an L6 305 for vehicle use. I have a '50 Chev with a 216 and they made a 262 truck version but I never heard of the inline 305.
A good place to get the answer would be at http://www.inliners.org/
Those guys is inliner crazy.



site1013_t.jpg

PB 8)
 
My Dad had a 1949 GMC truck that he hauled logs on when I was just a small boy. It had the 305 straight six with a five speed and two speed rear end. No muffler, just a straight pipe that came up behind the cab. You could hear him pulling Granite hill from our house about two miles away. He pretty much wore it out and parked it after buying a 1953 International that was in real nice shape but had a little 240 Silver Diamond six with a four speed with electric shift two speed axle. It drove really good but was way underpowered compared to the old Jimmy, he always talked about rebuilding the GMC but never did. It eventually got scrapped, I wish I still had it. I do have the International, though :D It needs a lot of TLC, but it is still on my list. Gotta finish restoring his old D2 Cat first.
Joe
 
That V6 was also offered as a V12. Just two of them put together. I've seen three of those engines. One had thrown a rod or something it had a broken block. I don't know what I'd do with one but it would be neet to have one. That V6 was also offered as a diesel just change the heads. My guess on the 305 I6 is some one was calling the 302 a 305. I had a neighbor that had one in a 701 New Idea powerunit they had lots of problems with it and the engine they replaced it with. We have the same engine in our 702 and 704 powerunits and haven't had any problems with them.
 
My Dad always said it was a 305. He said that this truck had been an old gas powered semi. And yes, it was a TRUCK, not a pickup. I do know that it was an I-6, and it was a large engine.
Joe
 
Joe, at one time GM had 3 different famlies of I6s. There was the "small" sixes - 228/270/302, a "medium" size family & a "big" family which included a 477(?) & a 500+ ci engine. Its possible that your dad's truck had one of these engines in it. Interesting to note, for a long time ford was the only manufacture to have a V8 in a truck, everyone else had I6s. Take care,
Edwin
 
Thank you Edwin,
I was too young when we had that truck to remember a lot of details. We played in it as children, I remember "shifting" all of the gears, also in his old Studebaker 6x6. They were both scrapped when I was a teenager, I hated to see them go but times were tough then and we needed the money. I'm sure that the engine was bigger than the small block series, it was probably of the medium size family. This truck had full size 10.00-20 tires on it and was licensed for about 32,000 GVW. I wish we still had some photos of it but they all burned in our house fire in 1970. Hence the need to sell off as much scrap as possible. I'm sure that it was perfectly rebuildable but the International had an exceptionally nice cable loader on it and got better gas mileage too. We hauled a lot of logs on that Cornbinder, I got to pull the cable out and set the tongs. I always enjoyed working with my Dad.
Joe
 
while Chev trucks ran the 216, then the 235.and rarer 261 (it had exhaust valve rotators!) GMC had its own line of premier I6's. As noted, the 228/248 (changes in bore/270 (248 plus stroker crank) , and the 302, which while outwardly was identicle, had a slightly longer block. These Jimmy truck 6's are not to be confused with Chevys, which were just car engines. The GMC's had forged Al, expansion slotted pistons, stellite seats, i believe the rods were forged also. I got a Floyd Clymer "How to Hotrod Your Chevy ^ book, CR about 53. It has a chapter or 2 on the GMC's & some eye popping pictures. These beasts were so king hell for stout they were the choice of early Salt Lake guys & "pole racers"- guys who dragged from street pole to street pole. Being so more robust than the Chevy 6, they were cranking out 300 HP on alchol/benzin in the early 50's with STOCK crank, rods, & pistons (Venolia!) Man-A-Fre or was it Hildebrand- made Al direct port injector heads for them. Imagine finding one of THOSE at a swap meet! The stock carbs were elegant, tall Zenith 1bbls, with changeable venturis. You just had to go over the details of one to see that it was a real, long lived, king hell truck engine...only 4 mains, as was the practice. ...I mourn thier passing. (Plus, they looked good: the head, rocker box, & side cover had very pleasing lines....Mutt
 
GMC "big" inline series were 361, 426, and 477 cubic inchers. I have a manifold on eBay for one right now. The 302 was the biggest of the "mid size" Jimmy's. I've got one of those ready for sale too... http://www.oldgmctrucks.com/Photos/GMC_Numbers.htm They were replaced by the V6 series in bigger trucks, the Chevy 230-250-292 in light and medium duty stuff. The 305 V6 was the smallest with 351, 379, 401, and 478 inchers following. The V12 was a 702 incher from a doubled up 351 internals ans heads- all 4 of them. It had it's own block casting, contrary to an earlier post. There were Magnum versions with better heads. This will give a good rundown on the monsters. With a front dress change the bigger ones will work in pickups! http://www.6066gmctrucks.org/EngineData.htm
 
Used to drive a 1960s GMC sries 4000 fire truck with a 305 V6. When it got tired I had a 401 Magnum built for it; what a difference in pulling hills with a full load. Same fuel mileage far as I could tell.

Breaking that combo in, I ran into a guy with a 1-ton 60s GMC pickup that had originally come with a 305 V6. He liked that V6 line, and had replaced the engine with 351 and 401, then finally a 478 Toro-Flow, the above-mentioned diesel. He then turbocharged the diesel, and it had some awesome power. Funny thing he mentioned that every one of those V6s he'd had in there got a best of 11mpg, up to & including that turbo-diesel! He used it to pull a fairly heavy 5th wheel trailer.

GMC also had a 637 cubic inch V8 configuration off that basic V6 design. Have only seen a couple of those here in SoCal.

Some GMC school buses were available with the very torquey 478 Toro-Flow diesel, and certain lazy bus drivers would just floor the accelerator pedal at a lugging speed, rather than downshift. The torque was so great that it could actually snap the crankshaft!

The web site previously referenced http://www.6066gmcguy.org/ has a ton of info on these neat old engines.

J.R.
 
The 302 l6 was produced from 52-58. It had a 4 in bore and 4 in stroke. It had 4 mains and shares the same bearing dimensions as the 235 6. If you want a good reference for engines produced over the years get a Sealed Power/Federal Mogul bearing catalog from your local parts supplier. Lots of good info.
 
The 305 v6 was produced from 60 to 74 and some of the variations were up 401 cu in.

The 305 cu in had a 4.250 bore and 3.580 stroke (huge) these were mostly gas engines and some diesel variations.

I have seen some of these engines in early GMC pickups and they fill the engine compartment pretty well. I don't know if they were factory installations but to a kid working in a service station they were pretty cool.
 
I know this is an old thread, but...
I had a 1967 GMC 1/2 ton with leaf rear susp. and a 305 V6. Trying to convince the zit-faced newbie behind the parts counter that GM made this engine and it wasn't a 305 V8 was pretty frustrating.
They actually made this engine all the way to 478 CID!! for the larger trucks and also a 702 CID V12 version!
 
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