1979 Chevy Scottsdale K30 with 400 CID Engine

[Phishin]

I'm looking at a 1979 Chevy Scottsdale K30 (1 ton, 4x4) pickup truck. It's an extremely low mile truck (16k miles) as it's being retired from a Fire Station.

What do you guys knows about these 400 CID small blocks? From what I read, they were prone to over-heating due to no water jackets between all the cylinders. Is this right? What else can you tell me about this truck or this engine? It comes mated with a 3-speed TH400 transmission, a NP205 transfer case, and heavy duty 1-ton axles.

What are your opinions on this truck? Experiences?

 

[supton]

Probably well maintained, but even garaged you can have rust issues. Do the regular inspection. Low miles, but fire truck, so it may have idled a lot. Was this a forest fire response vehicle? May have gotten little use as a result.

 

[Killer223]

on of the best truck you can ever find. the frame under the steering box tend to brake with larger tires. the rear frames where the shocks bolt up tend to brake when air shocks are added.
else they are a KILLER combo.
the 400 small blocks are a great engine. the turbo 400 trans as long as the torque converter locks up and about as bullet proof as they get and the 205.. well it's a legend in it's own write.
great great trucks. take a lot of abuse and still get you home.

 

[supton]

I wonder if it has 4.56's already in the diffs. I'd go look up GM RPO codes and write them down; then you can look at the build (option?) sheet (on the glovebox door IIRC) and see what it has.

Want to say it should have HEI ignition, no electronics otherwise. No catalytic convertors either? The 400 isn't a lockup transmission (let alone overdrive). So don't expect mpg.

What's the plans for the truck? A beater, a daily driver, a brodozer?

 

[hatt]

That's a nice find.

 

[c502cid]

With the exception of 79 and 80, most of these came with the 454 which is a much better option if you are doing any kind of heavy hauling. I owned an 80 K30 with the 400 and it was a dog pulling in the mountains around here. The drive line parts alone are worth big bucks. I only have one of them now but I've owned probably 20 over the years.
91 was the only year for the 4L80E overdrive trans mated to a NP205 transfer case. I have one in my shop ready to go in my 84!

 

[440Magnum]

Originally Posted By: Phishin
I'm looking at a 1979 Chevy Scottsdale K30 (1 ton, 4x4) pickup truck. It's an extremely low mile truck (16k miles) as it's being retired from a Fire Station.

What do you guys knows about these 400 CID small blocks? From what I read, they were prone to over-heating due to no water jackets between all the cylinders. Is this right? What else can you tell me about this truck or this engine? It comes mated with a 3-speed TH400 transmission, a NP205 transfer case, and heavy duty 1-ton axles.

What are your opinions on this truck? Experiences?


The 400 SBC was far from GM's finest moment. Siamesed bores, uneven cooling, and tendency to blow gaskets cylinder-to-cylinder. There's nothing fundamentally wrong with siamesing the cylinder bores in an block designed for it from the start, but it was added to the SBC design for the 400 alone, so the water flow patterns aren't optimal for a siamese-bore engine. And the cylinder head clamping isn't adequate for the narrow sliver of gasket that is separating combustion chambers. Also, the long stroke and same rod length as a 350 gives it the worst rod angularity and the fastest cylinder wall wear of any factory SBC. If its a nice truck, I'd still buy it and just budget on scrapping the 400 when it becomes a blue-smoking problem, which might not be for a very long time, honestly. There are a zillion and one cheap replacement options out there, from junkyard 350s, to build-your-own or crate 383s (Blueprint Engines gets good reviews lately), or the all-popular LS swap (most work, biggest reward since you get rid of the SBC architecture entirely).

 

[Phishin]

Originally Posted By: supton

What's the plans for the truck? A beater, a daily driver, a brodozer?


I'd just drive it work (3-4 miles each way) and around town. I also need a truck because I have a couple of pet goats, so I need to pick up hay, haul dirty bedding to the compost/recycling center, etc. etc.

The only "thing" that bothers me is, it's full-time 4x4. There is a selector on transmission hump and it reads: 4 Hi, Hi Lock, and Low Lock.

Does anyone know the actual difference between 4 Hi and Hi Lock?

Originally Posted By: supton
Was this a forest fire response vehicle? May have gotten little use as a result.


Yep. It was used as a "Brush Fire" truck.

 

[Phishin]

Originally Posted By: Killer223
on of the best truck you can ever find. the frame under the steering box tend to brake with larger tires. the rear frames where the shocks bolt up tend to brake when air shocks are added.
else they are a KILLER combo.
the 400 small blocks are a great engine. the turbo 400 trans as long as the torque converter locks up and about as bullet proof as they get and the 205.. well it's a legend in it's own write.
great great trucks. take a lot of abuse and still get you home.


This truck is 100% stock. It has ONE slight surface rust "bubble" under the Scottsdale emblem on the driver's side.

 

[Astro14]

On the other hand, my parent's '76 Impala SW with a 400 SBC went over 200,000 miles, including three teenage drivers (one of whom was a future fighter pilot and used to explore the performance limits of the car) with absolutely ZERO engine or transmission issues.

All on Dino 10W40, naturally...that came from cans...

 

[IndyIan]

Originally Posted By: Phishin
Originally Posted By: supton

What's the plans for the truck? A beater, a daily driver, a brodozer?


I'd just drive it work (3-4 miles each way) and around town. I also need a truck because I have a couple of pet goats, so I need to pick up hay, haul dirty bedding to the compost/recycling center, etc. etc.

The only "thing" that bothers me is, it's full-time 4x4. There is a selector on transmission hump and it reads: 4 Hi, Hi Lock, and Low Lock.

Does anyone know the actual difference between 4 Hi and Hi Lock?

Originally Posted By: supton
Was this a forest fire response vehicle? May have gotten little use as a result.


Yep. It was used as a "Brush Fire" truck.

4 Hi will be AWD (centre diff opened) and Hi Lock will be high range but with the centre diff locked giving you 4WD. You'll want to keep it in 4 Hi almost all the time on a road. Lots of newer vehicles use the same setup.

 

[440Magnum]

Originally Posted By: Phishin

Does anyone know the actual difference between 4 Hi and Hi Lock?



IIRC, Hi-lock and Lo-lock both lock the center differential. That means that if both rear wheels lose traction, the fronts are still going to receive full torque and vice-versa, where as with regular Hi or Lo the torque is equalized between the front and rear axles. IOW if the rear axle loses all traction, almost no torque goes to the front axle either. Either "lock" mode is not to be used on pavement because the slightest attempt to go around a corner will cause driveline bind.

 

[Chris142]

The late 70's Chevrolet v8's were known to eat cams. Idling is the worst for them and I'm sure it has idled a bunch.

 

[440Magnum]

If you do wind up winter-driving the truck, watch out for the usual square-cab Chevy rust areas over the wheel openings... rear in particular. Probably worth some proactive treatment if it doesn't have any rust started in there already.

 

[SeaJay]

There is probably a lot of good about that low mileage truck, but there are still lots of parts & systems that are over 35 years old that will be breaking from time to time.

 

[Phishin]

Originally Posted By: 440Magnum
If you do wind up winter-driving the truck, watch out for the usual square-cab Chevy rust areas over the wheel openings... rear in particular. Probably worth some proactive treatment if it doesn't have any rust started in there already.


For sure....if I do get this truck, I'm immediately running it down to a Krown shop to get it treated right away.

Originally Posted By: SeaJay
There is probably a lot of good about that low mileage truck, but there are still lots of parts & systems that are over 35 years old that will be breaking from time to time.


No doubt....that's part of the "fun". With a truck this nice, it actually makes sense to replace the worn parts, and things that break/fail as time goes on, with high quality replacements.

I'm going to inspect and drive the truck this Saturday. Supposedly the Fire Station has all the service records since new, since they bought it new.

 

[mlatour]

If the transfer case has a differential and allows full-time FWD,
it likely isn't an NP205 but an NP203 which I don't think was offered in 1 ton trucks.

I had an NP203 in a 1976 K5 Blazer (350, TH350, NP203, Dana44 / GM12bolt)

The NP203 has a chain drive to run the front output, the NP205 has a more durable gear drive.
The are aftermarket kits to pick up the chain's slack without requiring complete disassembly.

Trucks with the NP203 have no selectable FREE/LOCK front hubs,
only a simple hubcap with a gear with inner&outer splines locking the hub to the axle.

An NP203 selector will have from back to front: HI-Lock, Hi, Neutral, Low, Low-Lock
there are aftermarket part-time kits that replaces the center diff. assy.
(and making 2WD-Low a posibility) placing the lever in either 'Lock' position engages the front output.

In 1/2ton applications, to counter the Full-Time FWD / NP203's horrible fuel mileage
it was replaced by the NP208 (aluminium cases versus cast iron of older cases)
and a vacuum axle disconnect to still allow convenient shifting 'on-the-go'.

 

[joegreen]

I daily drive a 78 k20 40 miles per day. It has a th400 transmission, 350ci sbc, and an np203 awd transfer case. Having a three speed transmission is not to bad depending on the gearing. I have 3:73 gears and i turn between 2500-3000 rpm at 55-60. On these trucks the frames can crack by the steering box with over sized tires. Its not really a big deal. There are weldable or bolts on plates that fix that issue. The th400 is a very strong, reliable, simple transmission. Alot of people complain about the np203 (which im guessing yours might have if it has hi-loc, hi, N, low, low-loc) because its a full time transfer case. Its a pretty stout cast iron unit and its convenient not to have to get out and lock the hubs in bad weather. The front axle is most likely a dana 60 and the rear might be a corporate 14 bolt or dana 60/70. I dont really know anything about the 400ci engine. Overall they are good trucks. The frames are not built as strong as modern truck frames but are still plenty strong as long as its not all rusted apart underneath.

 

[Oldmoparguy1]

Originally Posted By: Astro14
On the other hand, my parent's '76 Impala SW with a 400 SBC went over 200,000 miles, including three teenage drivers (one of whom was a future fighter pilot and used to explore the performance limits of the car) with absolutely ZERO engine or transmission issues.

All on Dino 10W40, naturally...that came from cans...


Now there is a testimonial !!

 

[hatt]

Quote:
In 1/2ton applications, to counter the Full-Time FWD / NP203's horrible fuel mileage
it was replaced by the NP208 (aluminium cases versus cast iron of older cases)
and a vacuum axle disconnect to still allow convenient shifting 'on-the-go'.


I have an 84 K10 with a 208 and auto hubs. It doesn't use vacuum for anything. The front drive shaft spinning will engage the hubs. To unlock, shift into 2wd and back up.

Pretty sure the 3/4 tons of that same vintage did the same.