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Supercharged 4×4! 1974 Chevrolet K-20

Even if big-tired four-wheel-drive trucks are not your bag, check out the listing for this 1974 Chevrolet K-20 Custom Deluxe here on eBay. Power through the stream-of-consciousness single giant paragraph, and you’ll learn more about this $6000 Buy It Now truck than many six-digit listings. The phrase “one owner” often means the seller recently low-balled the “one owner” and now plans to double their money by flipping it as rapidly as possible. In this case, you appear to be buying a vehicle from the person who spent untold hours and dollars making it a genuine super-truck. Catastrophic engine failure sidelined the lifted Chevy, but the right buyer with mechanical skills and time to sort out the broken bits should end up with a thoroughly upgraded Squarebody Chevy. Upgrades from stem to stern include a (now damaged) boost-friendly engine setup, supercharger, upgraded cooling, suspension, stereo, and more.

The 162 cid B&M supercharger wears the “fastest turning” i.e. smallest pulleys for maximum boost. Bust out your power-adder books or the right web page and you can “do the math” to build a motor that matches your desired boost. The blown motor clearly pushed the mathematics –and mechanical components– beyond the breaking point, although you couldn’t rule out a freak part failure or human error in the engine build. You might get by with reworking the bottom end to suit the power-adder as-is, or go with a larger (slower turning) blower pulley for extended longevity. Let’s face it… any power adder on a V8 represents serious bragging rights when you pop the hood.

The seller details a host of electronic upgrades including audio, alarm, high-powered (and possibly illegal) headlights, and more. Nothing in the description suggests the builder slapped and bolted cheap parts onto this truck with no plan. Clearly the modifications came as part of a long-term relationship and a desire to improve every aspect of the driving experience.

The no-doubt entertaining event that blew the motor also trashed the rear driveshaft which in turn damaged one gas tank. Simply launching hard with monster torque working to spin oversized tires would be enough to shred a driveshaft. Good news includes the generally solid-looking underbelly of this beast. We’ve only scratched the surface on the details about this interesting ’74 Chevy. The price certainly leaves room in the budget. How would you rebuild this long-parked and thoroughly upgraded Chevy?

Comments

  1. Avatar Randi Bagley-Goodwin

    This would be so much fun! Brings back some sweet “muddin” memories!

    Like 2
    • Avatar RC Graham

      I’m more the Jim Garner, walking the racecourse type. However, this does seem like a lot of value for the money. No A/C though. That’s tough in the Great Sonoran Desert. Still…

      Like 2
  2. Avatar Stan

    Looks like a fun garage. Sportbike, dirtbike, heavy chevy 4×4. Lots of boxes , must be a case of beer 🍺 or two around 👍

    Like 8
  3. Avatar Big Al

    This truck has been beat too hell !!! 225,000 hard miles.
    I love the picture of the case of oil on the front seat.
    You’ll need a case or two if you buy this. Not sure why sellers don’t take an hour and clean up around the vehicle their selling so we can see what we might want to buy. 😒😒

    Like 10
  4. Avatar CCFisher

    If it had a catastrophic failure, how “boost-friendly” could it be?

    Like 7
    • Avatar Todd Fitch Staff

      Hello CCFisher: Clearly not friendly enough! The listing mentions Competition Cams blower cam and TRW 7.5-1 forged blower pistons. Those components are part of a boost-ready build. Damage could have come from being too lean, incorrect timing, over-reving when the driveshaft let go, or the obvious… too much boost for too long. There’s a big difference in your engine build based on how much time will be spent at WOT. Will the motor be used for a few quarter-mile runs or an afternoon of road-racing? If you don’t do the calculations or base your build on one that did, you’re just bolting on hopes and prayers. Thanks for your comment!

      Like 8
      • Avatar CCFisher

        Hi, Todd. I read the seller’s word blob, and I didn’t see any mention of upgraded connecting rods, and that’s ultimately what failed. As you note, it could be for a variety of reasons, but the first thing everybody is going to blame is the supercharger setup. The ad suggests the supercharger has 50,000 miles on it, and that’s definitely impressive for a home-grown setup, but it’s even more reason to make sure that every necessary component has been upgraded, and that’s much more than just the engine. I have an acquaintance who spent many thousands on a fantastic engine build, then installed it using stock motor mounts. When the left mount broke, the throttle linkage jammed open. Lucky for him, a poorly routed fuel line kinked and shut off fuel flow. I have a degree in mechanical engineering, so I know a little about what’s needed to get torque to the ground, and some of the builds I see make me shudder. “Ok, bud. I just hope I’m not in the next lane when those weak springs let go and the axle twists out from under you.”

        Like 3
      • Avatar RC Graham

        CCFisher – Had the exact same problem with 1968 Impala wagon 327 we bought new. We went through 4 or 5 sets of the most poorly designed engine mounts in history – under warranty.

        “See the USA, from the side of the road…”

        When the engine runs away due to mounts, linkage, or whatever reason – you grab the keys. Solves the problem.

        Kinked fuel line, too..? There’s luck involved, but it ain’t the ‘good’ kind.

        When we were finally out of warranty, we had the mount chained and that was that. Standard racer’s fix for a stupid design.

        Like 0
    • Avatar GIRTH

      It won’t fight it, boost friendly.

      Like 0
  5. Avatar geichele

    Big-tired four-wheel-drive trucks are definitely “my bag”…I have three of them! (Four if you count my Jeep Wrangler.)

    Like 2
  6. Avatar Rw

    I like it doesn’t have body lift or 6in Blocks.

    Like 1
  7. Avatar Jose Rovirosa

    Parts for these things are relatively abundant and reasonable, not to mention that a non-rusty, 4wd squarebody is hard to come by these days. 6k doesn’t sound too out of line, but I’d probably budget at least that much to get it back to solid driver status.

    Like 4
  8. Avatar Troy

    Square body 4×4 I’m surprised the bidding is only around $6k

    Like 3
  9. Avatar B302

    What I find curious is in the ebay write up is that the truck has as least four alarm systems:
    Truck has a keypad monitored alarm that is fully backwired. Alarm stays functional even if wires are cut to battery or siren. In fact cuting any wires trips the alarm.

    Also has a full Alpine remote alarm with the optional electronic motion sensor that resets to compensate for parking tilted to the side or on any hill.

    Also has a Ungo remote full alarm set as a pre alarm (Ungo remote is missing but I should be able to set another remote if supplied with the brain.

    There is also a page Alert paging system but the pager is missing. I may have a complete spare new in box paging system available separately.

    The triple failure: engine, driveshaft and gas reminds me of an incident I witnessed. I use to help on a NHRA SS/E (Super Stock E) 427 1969 4speed Camaro. On one occasion the driver did his burnout, pulled to the line and revved the engine. The light turned green, the car did not move and the rev limiter save the engine. The transmission, driveshaft and ring and pinion were all destroyed. I have seen multiple failure several times and it still confuses me.

    Like 0
  10. Avatar Karl

    Just the looks of this thing makes me cringe. Trying to use stock drive shafts with the mods done to the motor especially in this application, it’s only a matter of when. If the engine tossed a rod the only way you can look at it is your going to build a new engine for it. Not nearly enough details on the engine damage. 50k on the blower? Questionable and if true it was running very little boost. Looks like a project I want nothing to do with.

    Like 0
  11. Avatar Mountainwoodie

    Honey……I dropped the driveshaft…..oh and blew a few rods………uhuh…….another 15 K and you’d be up and running. Maybe

    But………… qui es muy macho? Este camion o Uno Prius?

    Like 0
  12. Avatar R.Lee

    I would give 6K for this truck if I could retrieve it. Cali truck with minimum rust. Dual shock front, good transfer case. 44 front, but is trash anyway and can be upgraded but why? Need a 60 anyway if you are going to get power down.

    Worn out TSL’s full time 4, laying down the power, no wonder the front diff grenaded. Putting it all on the rear floater. I bet it was quite the show picking up all the parts.

    To bad about the front fenders being bobbed but who cares. Put in my 60 and a real 500 easy HP 454 BB some 4.56 gears with lockers. All of that is not free but not costing me anymore with them sitting idle on the pallet racks. Driveshafts and axles are cheaper than grenading HP.

    Having 70 years of Chevrolet truck parts comes in handy for trucks just like this. Too bad it is not 1,000 miles closer. Even in MO. 6,000 is a good deal. 6K in Cali is a steal.

    Like 2

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