Big 10

[buckshot]

what can y'all tell me about the big 10 series trucks?i've been looking for a good 3/4 ton work truck and came across a big 10.i thought i've heard the big 10 is a beefed up 1/2 ton thats almost like a 3/4 ton.right?,wrong?
any help would be appreciated.
buckshot.

[bigblock73]

This should help.

http://www.73-87.com/Special_Editions/Big%2010.htm

[bigblock73]

Originally Posted by moonlight

Hey Jeff,
I like those last 3 images ....they look familiar
Mark

Yes they do, I believe you posted them on this very board.

[79BIG10]

I love having a Big 10 truck

[80BIG10]

My Big 10 has been a great truck. I would recomend one to anyone that needs to haul stuff. Out in this area most of them were used for ranch trucks. They are a great truck and will definatily handle more than a standard 1/2 ton.

[EricS76]

Big 10's are good for a half ton truck, but if you're thinking you're going to need a 3/4 ton to tow/haul fairly heavy, you should get the 3/4. I believe the Big 10's are rated around 6,500lbs GVWR. Some 3/4 tons are rated at 8,500lb, so you're looking at a ton more weight rateing.

[buckshot]

thanks for all the help i appreciate it.
bigblock73 thats a great site-lots of information.
i do have a few more questions though,what GVWR is a standard 3/4 ton?
also,i havn't looked at the truck yet but i had the guy that told me about it get the weight rating (6050 lbs.) and some option codes from the glove box 1F44-heavy duty chasis?
1MX1-auto transmission (is that a turbo 350 or 400?)
i've got another truck (3/4 ton) to go look at but,if it doesn't look as good as the big 10 (no rust ,very few dents and dings) i may end up with the big 10.
i do plan on using it to haul loads of 8" concrete blocks about 50 miles so do y'all think a big 10 is up to that or would i be better off with a 3/4 ton?
thanks again,buckshot.

[KIILew]

Buckshot:

Concerns like yours about selecting the right vehicle for cargo carrying requirements, and more specific interest in the Big 10 occasionally appear in these forums, so I thought I would throw in my two cents worth. I see you posted your question a long time ago, so you may have already decided, but perhaps some of the following info might be useful to others.

As others on this board may note, brevity is not my forte. Most of this stuff is probably not worth wading through for your purposes, but maybe somebody can find something of interest (or contention) in it.

Some Big 10 history:

The Big 10 was promoted as a heavy duty two wheel drive half ton for the 1975 through 1980 model years. Although it offered truck buyers somewhat more load carrying ability than the standard C10 half tons, its real advantage- -and the motive behind its conception- -was that it provided buyers with the opportunity to purchase a half ton truck that was unencumbered by the dreaded catalytic converter, which was first introduced to a skeptical American car buying public just in time for the 1975 model year.

For several years prior to that time, all trucks with gross vehicle weight ratings of 6,000 lbs and below were forced to comply with the strict “light duty� emission standards that also affected passenger cars. The EPA’s selection of the 6,000 lb. threshold likely reflected its awareness that that number had become the traditional de facto dividing line between half ton and three quarter ton trucks. And since the vast majority of trucks purchased by consumers were half tons, limiting the emission constraints to them probably seemed to be a reasonable compromise to the government, while avoiding potential protests about cost and implementation by the truck manufacturers- -and their commercial customers- -that might have occurred had the laws been expanded to the heavier vehicles.

Before the advent of the catalytic converter, the distinction between “light� and “heavy� duty emission controlled trucks was largely ignored by consumers. But the converter’s introduction and it’s nearly universal application in 1975 “light duty� emission vehicles changed things dramatically. Unlike the EGR and evaporative canister devices that preceded it, the converter had an exclusive appetite for expensive unleaded fuel which outraged truck buyers- -and especially fleet purchasers- -in a nation that still had access to relatively cheaper leaded fuel.

Recognizing a new marketing opportunity, or necessity, light truck makers made relatively minor spring, tire, and brake modifications to their existing half ton models to push GVWR’s just over the 6,000 lb. threshold. Ford lead the way by introducing the heavy half ton F150 as an alternative to their traditional half ton F100, while Chevrolet introduced the “F44 Heavy Duty Chassis� package as an option for their C10 pickup.

These new-for-1975 models moved into the “heavy duty� emission classification enjoyed by three quarter ton and heavier rated models. This allowed the F44 equipped C10, later dubbed the “Big 10� for market visibility, to comply with government emissions regulations using only a PCV valve, heat stove, and relatively loose “controlled combustion system� (CCS) tuning. In contrast, the 1975 “light duty� emission certified standard capacity C10 required a PCV valve, heat stove, stricter “controlled combustion system� (CCS) tuning, EGR, evaporative canisters, a vacuum activated early fuel evaporation (EFE heat riser) valve, special outside air ducting to the air cleaner, and a catalytic converter. But by 1979 the EPA- -following legislation enacted in California a year earlier- -raised the light duty/heavy duty emission dividing line from 6,000 to 8,500 lbs. GVWR which brought all heavy duty half ton and almost all three quarter ton pickups into the light duty emission fold. Following this legislation, consumer appreciation for the heavy duty half ton concept- -so gelded- -largely faded away.

A look at the chassis component differences that distinguish C10’s, Big 10’s, and C20’s:

What does this have to do with hauling around cement blocks? Well, let’s redirect the discussion to some component specifications for standard half ton C10’s, heavy duty half ton Big 10’s and three quarter ton C20’s. Note that the following pertains only to two wheel drive vehicles.

A careful study of the 1975 Chevrolet Light Truck Data Book provides some insight here. Leading into 1975 the regular (i.e. not heavy duty) C10 pickup offered several different GVWR packages. Those ratings were 4,900, 5,300, 5,400, 5,600, and 6,000 lbs. Beyond this, the new F44 Heavy Duty Chassis package provided a 6,200 lb. GVWR. Mid way through the model year, Chevy broadened the F44’s choices by adding a 6,050 rating option to the existing 6,200 lb package. This late-availability 6,050 pound option replaced the C10’s 6,000 lb. package, which was cancelled.

All seven of these C10/ Big 10 GVWR packages used the same basic frame with a side rail width, depth, and thickness of 2.30�, 5.92�, and .156� respectively. The frame section modulus was 3.14. Also, all of these packages utilized the GM 12 bolt semi floating axle with a capacity of 3,750 lbs., and used a standard 15�x6� five lug wheel rim. Differences in GVWR were attributable to choices in spring and tire capacities, and brake system components. Some engine and transmission option recommendations/restrictions also accompanied different GVWR offerings.

The base 4,900 lb. rated C10 used the following components at minimum:
• 1,550 lb. capacity front springs.
• 1,550 lb. capacity rear springs (consisting of 4 leaves, and having a length of 52� and a width of 2.5�).
• Front and rear tires with a load capacity of 1,470 lbs.
• Manual brake system (the 4,900 lb. rated C10 was the only pickup in the entire C/K10/20/30 lineup to use manual brakes. The front disk brakes had a diameter of 11.86� and a thickness of 1.28�. Rear brake drums measured 11�x2�).
• Standard LD4 250 1 bbl. I6 engine w/M15 Saginaw 3 speed manual transmission.

The 5,300 lb. GVWR required the following minimum additions and/or substitutions:
• Option code J50 light duty power brake system (front disk and rear drum specifications remained the same as shown above).
• Option code M20 Chevrolet CH465 4 speed manual transmission (recommended at 5,300 to 6,050 lb. GVW levels when LD4 250 1 bbl. I6 engine was selected; M15 3 speed manual transmissions remained available w/larger engines).

The 5,400 lb. GVWR required all items necessary for the 5,300 lb. rating plus the following minimum additions and/or substitutions:
• Front and rear tires with a load capacity of 1,610 lbs.

The 5,600 lb. GVWR required all items necessary for the 5,400 lb. rating plus the following minimum additions and/or substitutions:
• Option code G50 heavy duty rear springs (2,000 lb. capacity for this application. These springs consisted of 8 leaves, and were 56� long x 2.5� wide).
• Front and rear tires with a load capacity of 1,790 lbs.

The 6,000 lb. GVWR required all items necessary for the 5,600 lb. rating plus the following minimum additions and/or substitutions:
• Option code F60 heavy duty front springs (1,625 lb. capacity for this application).
• Option code J55 heavy duty power brakes (this system replaced the lighter capacity J50’s single diaphragm brake booster with a dual diaphragm unit and included larger 11.15�x2.75� rear drum brakes for C10 applications).

The 6,050 lb. GVWR package, which represents the lower of two F44 Big 10 capacities, was specifically identical, in terms of chassis and suspension components, to the 6,000 GVWR package which it superseded mid-year. Gross axle weight ratings at this GVWR were 3,100 lbs in front and 3,580 lbs. in the rear, and are the same as those cataloged for the 6,000 lb. model. The 50 lb. increase in GVWR appears to be a result of “on paper only� engineering. Emission control equipment was the only significant difference between the 1975 6,000 lb. and 6,050 lb. packages.

The 6,200 lb. GVWR was the maximum F44 option, and required all items necessary for the 6,050 lb. rating plus the following minimum additions and/or substitutions:
• Front and rear tires with a load capacity of 1,900 lbs.
• Option code LS9 350 4 bbl V8 engine w/M15 Muncie 3 speed manual transmission.

A similar breakdown can be made for the C20 regular cab pickup, which was available for ’75 with GVWR’s of 6,400, 7,100, 7,500, and 8,200 lbs. All four of these GVWR packages shared a frame with a side rail width, depth, and thickness of 2.30�, 5.92�, and .194� respectively. While the side rail width and depth were the same as the C10/Big 10 frame, the thickness was greater, and in fact was the same as the thickness of the frame used in the one ton C30. Not surprisingly, the frame section modulus, at 3.92, was also more robust. Finally, all of these packages utilized the GM 14 bolt full floating axle with a capacity of 5,700 lbs., and used a standard 16.5� eight lug wheel rim.

The base 6,400 lb. rated C20 used the following components at minimum:
• 1,750 lb. capacity front springs.
• 2,000 lb. capacity rear springs (consisting of 8 leaves, and having a length of 56� and a width of 2.5�).
• Front and rear tires with a load capacity of 1,990 lbs. (These used a 16.5x6� rim.)
• Power brake system with a dual diaphragm booster. (The front disk brakes had a diameter of 12.5� and a thickness of 1.28�. Rear brake drums measured 11.15�x2.75�.)
• Standard L25 292 1 bbl. I6 engine w/M15 Saginaw 3 speed manual transmission.

The 7,100 lb. GVWR required the following minimum additions and/or substitutions:
• Option code G50 heavy duty rear springs (2,600 lbs. for this application. These springs consisted of 9 leaves and were 56� long x 2.5� wide).
• Rear tires with a load capacity of 2,350 lbs.
• Option code M20 Chevrolet CH465 4 speed manual transmission (recommended at 7,100 to 8,200 lb. GVW levels when L25 292 1 bbl. I6 engine was selected; M15 3 speed manual transmissions remained available w/larger engines).

The 7,500 lb. GVWR required all items necessary for the 7,100 lb. rating plus the following minimum additions and/or substitutions:
• Front and rear tires with a load capacity of 2,780 lbs. (These used a 16.5x6.75� rim.)
• Option code J55 heavy duty power brakes (this system included larger 13�x2.5� rear drum brakes for C20 applications).

The 8,200 lb. GVWR was the maximum rating available for the C20 and required all items necessary for the 7,500 lb. rating plus the following minimum additions and/or substitutions:
• Option code F60 heavy duty front springs (1,900 lb. capacity for this application).
• Option code G51 extra capacity rear springs (2,850 lbs.).

What they will carry:

To assess the load carrying ability and overall stamina of each of these C10/Big 10/C20 GVWR levels, let’s calculate the payload that each GVWR can handle. This requires subtracting the curb weight of the empty vehicle from the gross vehicle weight rating. To eliminate some of the variables bearing on curb weight calculations and thus facilitate comparisons between the different GVWR/payload packages and series, let’s assume that all vehicles referenced below are optionally equipped with the LS9 350 4 bbl. V8, M40 Turbo Hydra-matic 350 transmission, N41 power steering and an appropriately sized spare tire. (The Turbo 400 transmission was available only with the 454 engine option on these vehicles.)

The payload of a C10 Regular Cab Fleetside with 8’ box, 4,900 lb. GVWR, and the above options would be calculated as follows with vehicle and optional equipment weights taken from the 1975 Chevrolet Light Truck Data Book:

Gross vehicle weight rating (lbs.) 4,900
Curb weight (lbs.) 4,014
Payload (lbs.) 886
…or 3 150 lb. people (using GM's favored methodology) and about 11 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 5,300 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 5,300
Curb weight (lbs.) 4,034
Payload (lbs.) 1,266
…or 3 150 lb. people and about 20 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 5,400 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 5,400
Curb weight (lbs.) 4,047
Payload (lbs.) 1,353
…or 3 150 lb. people and about 23 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 5,600 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 5,600
Curb weight (lbs.) 4,120
Payload (lbs.) 1,480
…or 3 150 lb. people and about 26 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 6,000 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 6,000
Curb weight (lbs.) 4,148
Payload (lbs.) 1,852
…or 3 150 lb. people and about 35 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with the F44 package and 6,050 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 6,050
Curb weight (lbs.) 4,124
Payload (lbs.) 1,926
…or 3 150 lb. people and about 37 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with the F44 package and 6,200 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 6,200
Curb weight (lbs.) 4,142
Payload (lbs.) 2,058
…or 3 150 lb. people and about 40 cement blocks at 40 lbs. apiece.

The payload of a C20 Regular Cab Fleetside with 8’ box, 6,400 lb. GVWR, and the options noted above would be calculated as follows

Gross vehicle weight rating (lbs.) 6,400
Curb weight (lbs.) 4,425
Payload (lbs.) 1,975
…or 3 150 lb. people and about 38 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 7,100 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 7,100
Curb weight (lbs.) 4,463
Payload (lbs.) 2,637
…or 3 150 lb. people and about 55 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with a 7,500 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 7,500
Curb weight (lbs.) 4,580
Payload (lbs.) 2,920
…or 3 150 lb. people and about 62 cement blocks at 40 lbs. apiece.

The payload of the same vehicle with an 8,200 lb. GVWR would be:

Gross vehicle weight rating (lbs.) 8,200
Curb weight (lbs.) 4,594
Payload (lbs.) 3,606
…or 3 150 lb. people about 79 cement blocks at 40 lbs. apiece.

Perhaps the most interesting comparison occurs between the C10 w/F44 6,200 lb. package, and the C20 w/6,400 lb. package. Despite the fact that the C20 has a 200 lb. heavier GVWR, its payload is actually 83 lbs. less than the Big 10’s! Of course, this is because the C20’s chassis is heavier by 283 lbs. But the parts that account for that extra weight offer significant benefits- -despite the Big 10’s slight advantage in ultimate payload capability, the C20’s stronger frame, full floating axle, and other more robust components suggest superior long term durability, particularly under near-maximum load conditions.

Moving beyond the 1975 numbers:

It is important to realize that the numbers I have selected above apply directly to 1975 model year vehicles. That said, most of this information is applicable with only minor adjustment to C10’s, Big 10’s and C20’s produced through the end of the 1980 model year. In fact, the most significant deviation occurred in the C20 line for the 1980 model year, when the 8,200 lb. GVWR was replaced by an 8,600 lb. option under the C6P option code. Since the “light duty/heavy duty� emission division point had been repositioned from 6,000 lbs. GVW to 8,500 lbs. GVW by start of the 1979 model year (1978 in California), the new for ’80 C6P option again allowed buyers to use leaded gasoline in a three quarter ton truck. Of course, the 1979 and 1980 Big 10’s were equipped with the full complement of light duty emission controls.

This above discussion should also be helpful in contemplating the relative abilities of half tons and three quarter tons offered during the 1981 to 1987 model years although there was some minor reshuffling of GVW packaging. Having lost its “non-smog control� appeal, the Big 10 package was no longer separately marketed from the lighter C10 models after 1980, although a maximum GVWR option of 6,100 lbs. was offered for C10’s from 1981 to 1987. Beyond this, some significant component changes occurred in the C20 lineup, such as the adoption of a semi floating axle for the first time in all three quarter tons (except those equipped with the 454 engine). Those changes might merit consideration in selecting one of the later models for your needs. But it is getting late, and that is beyond the scope of what I hoped to accomplish here.

Good luck as you consider your needs and choices!

Ken Lewis
Owner of a 1979 Chevy Big 10

[Slonaker]

Originally Posted by moonlight

Hey Jeff,
I like those last 3 images ....they look familiar
Mark

Originally Posted by bigblock73

Yes they do, I believe you posted them on this very board.

Perhaps he would like to have been credited with providing them?

Slonaker

[bigblock73]

Originally Posted by Slonaker

Perhaps he would like to have been credited with providing them?

Slonaker

It's been resolved.

[bigblock73]

Great info Ken!!

BTW - how have you been doing since we last spoke? Better I hope.

[KIILew]

Originally Posted by bigblock73

Great info Ken!!

BTW - how have you been doing since we last spoke? Better I hope.

Jeff, the break in my leg seems to be healing fine. Just went to the doctor yesterday (for my 6 week checkup) and he said that I should start putting full weight on it. He thinks I can toss the crutches in about three to five days. We will see!

[buckshot]

thanks for info Ken.it resolved alot of the questions i had.between your info and what i learned from the site bigblock73 pointed me to i believe i would be better off with a 3/4 ton.
and,i may have found one an 85 3/4 ton silverado with an 8600 GVWR-which brings up a few questions about it.it has a blown up/knocking 350 in it how hard would it be to switch to a 454?also,can someone tell me what optionYH6-bonus value option and ZQ2-operating convenience consists of?
again any help will be appreciated.
buckshot.

[KIILew]

Buckshot:

Your C20 C6P possibility sounds like a good one! These models were quite robust and offered the 400 transmission almost exclusively for those optioned with automatics (although in some years the 700 automatic overdrive was offered with the C6P chassis). The ’81 to ’87 models did come with a 6,000 lb. GM semi floating rear axle, except those that were factory optioned with the 454 engine. When the big block was optioned in, the familiar and desirable 14 bolt full floating axle was included.

With respect to the engine swap you are contemplating, I will keep mum on that as others know much more about the details of that exchange than I.

The YH6 package you are referring to varies in content from year to year, but it is nothing more than a pricing discount that was originally offered for bundles of popular options. Here is a link to an old thread from a similar question which I tried to answer with a little more detail…

http://67-72chevytrucks.com/vboard/s...d.php3?t=32808

The operating convenience package you asked about included power windows and door locks, which were also available as individual options.

Hope this provides some answers!

Ken Lewis

[80BIG10]

That is the most comprhensive write up on the Big10's that I have found. Thank you for all the great information. I looked in my door jam and found that my Big10 is the 6200GVWR.

On the downside my Big10 is a 1980 (manufacuted Dec 79) and has the extra full complement of light duty emission controls.

At least I have the larger GVWR.

Ken...how did you come across all the info?

Thanks,
Ken

[bigblock73]

Originally Posted by 80BIG10

Ken...how did you come across all the info?

Thanks,
Ken

Ken was conceived, born, and raised in a 73-87.

Just kidding, Ken just likes these trucks and apparantly has a large collection of information in his possesion (physically and mentally). He is a valuable resource to this board, I only wish he hung out more here. (hint hint)

Glad the leg is healing Ken, good luck with the walking.

[KIILew]

[QUOTE=bigblock73]Ken was conceived, born, and raised in a 73-87.

80BIG10:

I am glad you found some of that stuff useful, or at least entertaining.

As far as Jeff's comment above, I am afraid that I was neither conceived or born in a '73-'87. Having arrived in on the scene in 1965, that would not have been possible.

I did grow up with a '74 GMC C1500 and a '75 Chevy K20 on our family farm however. In the case of the '75, which was a Camper Special, I remember noticing GM had neglected to provide the appropriate camper package emblems on our brand new truck's side pillars. So upon our arrival home from the dealer, I fashioned substitute emblems by sticking adhesive gold letters on the truck. I was nine years old at the time.

I think that was the moment my father realized he had a very disturbed kid. And, yes, thirty years later, you and our fellow posters undoubtedly recognize that disturbance in my post above!

Anyway, part of my hobby is collecting factory literature, such as brochures, data books, new product guides, etc for these trucks and other vehicles. And that is most of the info above comes from.

Don't hesitate to ask if you think I might have some literature that might answer a question!

Ken Lewis

[Mike76251]

Ken.........you give Moses Ludel a run for his money.

[KIILew]

Originally Posted by Mike76251

Ken.........you give Moses Ludel a run for his money.

Thanks for the thought, Mike! I have Moses Ludel's various Chevy and...yes...Ford truck "bibles" and I do enjoy them. His practical knowledge and experience with cars and trucks is fantastic, and light years beyond mine. But I appreciate the comparison!

Ken Lewis