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Going from a V8 back to a 6...whaattt?!!!

Discussion in 'Under Construction' started by Sixy GMC, Oct 17, 2020 at 1:19 AM.

  1. Sixy GMC

    Sixy GMC Junior Member

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    DSCF1989.jpg What kind of idiot would go from a healthy running 350 SBC with a TH-350 back to a 250 six and a 3-speed manual? Well...me for one. Over the past 46 years I have been driving I have owned at least 10 vehicles that were powered by Chevy 6-cylinders with 3-speed manual trannies, and I have always been impressed by their incredible durability, simplicity, excellent power, and great fuel economy.

    Two months ago I was passing through Joplin, MO when I found an '83 GMC stepside for sale at a classic car lot. After several hours of negotiating I was able to lower the price from $11k to $7,500 and I bought it immediately for cash (a big reason why the seller lowered the price so much). The truck was a base Sierra 1/2 ton with no visible rust or body repairs, and a known owner history. The original engine emissions sticker was still on the radiator support and showed the truck was originally powered by a 250 six. The narrow brake pedal was from a truck that had originally had a clutch pedal, and the clutch pedal had been cut off at the top of the pedal arm with a cutting wheel. The shift quadrant ("PRNDL-ator") was blank which further confirmed it was a 3-on-the-tree truck. It was only after purchasing the truck that I thought to look at the SPID sticker in the glovebox which reiterated its cheapo drivetrain roots.

    The truck ran great with its 350/TH-350 combo, but it got pretty lackluster gas mileage...I drove it from Joplin to Columbus and averaged 12.5 mpg going 75-80 mph on the interstate. I thought to myself that it would be nice to someday turn the truck back to original if I could find a suitable donor truck with all of the missing components, but trucks like that are pretty hard to come by. I searched on "car-part.com" to try and find a complete parts truck, but found incomplete messed-with trucks that were hundreds or thousands of miles from me. By chance, I located a complete '83 Chevy C10 long bad on Craigslist in SE IN...just 2 1/2 hours away. The seller was a tow truck driver who hauled the truck away from the family of the deceased original owner...you guessed it...they had zero interest in the oddly-shifted classic pickup.

    The truck was almost rust-free and had its complete original 250 six and 3-on-the-tree shifted manual tranny. The mileage showing on the odometer was 77k, and the owner's family told the tow truck driver that that was its correct mileage. I asked how much it would cost to buy the engine, tranny, radiator, tranny crossmember, engine mounts, clutch pedal, exhaust system, and the steering column including the shift rods. He said $750 and we settled on $650. I showed up 2 days later to pick up the pulled drivetrain and other associated parts. For good measure he threw in the nearly perfect instrument panel bezel and speedo/gas gauge.

    I have a good friend who lives near me on the north side of the Columbus metro area, Scott...he's an excellent mechanic and body man...a guy who has made his living that way for the past 35 years. He agreed to do the swap for $500.

    DSCF1636.jpg View attachment 164968 View attachment 164968 DSCF1982.jpg DSCF1987.jpg
     
  2. Sixy GMC

    Sixy GMC Junior Member

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    One of the most challenging parts of this swap was that Scott would have to fix the worn-out shift collar on the steering column (it had cracked inside the collar which allowed it to move around too much and caused a great deal of wear to the movable collar which the shift lever moved and actuated gear changes. I had 2 decent 3-on-the-tree columns in my parts stash in the basement...one from a '72 Nova and one from a '69 Firebird. Scott disassembled all 3 columns and determined that the '69 Firebird's shift collar was in excellent condition and would be perfect for replacing the collar. The '69 column was virtually identical to the '83 column!
     
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  3. 45tt

    45tt Member

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    Very cool story. There’s nothing wrong with putting it back to the way it left the factory. There are a lot of modified trucks out there, but when you see one that is original or looks original, it’s a real treat to see.

    post some more pics, I always liked the step sides.
     
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  4. Sixy GMC

    Sixy GMC Junior Member

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    45tt...thanks for the reply. Here are a few more of the swap which is nearing completion (it'll probably be running today or tomorrow).

    Before swapping anything, I spent about an hour with a power washer to get some of the oil and grease out of the engine compartment and off the 350. According to the guy I bought it from, the truck's swap occurred sometime around 2004 or 2005 when the original owner died at age 59. The truck spent most of its life in or near Okla City, and it still has its original metal dealership emblem on it, and its warranty booklet has the original owner's name, Clayton Dean (about as Okie a name as I have ever heard :).

    The engine was out in about 2 hrs, and separating the engine and tranny was the key to the job going so smoothly. I fired up the power washer again to get every last bit of crap out, and to thoroughly clean the tranny crossmember and frame rails. The only rust found anywhere on the truck was 2 small holes located at the bottom sides of the radiator's core support...Scott fixed both of the holes and I added that labor to the truck's bill (one of the photos shows his repair...not perfect, but pretty damned close...the repair was covered up with Rustoleum metal etch primer and a couple of coats of dark charcoal satin finish...nearly a perfect match to the truck's original engine compartment dark gray paint).

    The truck's level of originality (in spite of the SBC swap) is impressive, and the donor '83 C10 was also amazingly unmessed with. The donor truck provided everything needed to accomplish the swap with a minimum of drama, and even had its original metal radiator tag still in place.

    Among the new parts going on the GMC are a rebuilt radiator (new 2-row core), new clutch, pressure plate, throwout bearing and pilot bearing, new AC plugs, new AC cap and rotor, new AC plug wires (an NOS set dated 1978), and obviously fresh fluids. DSCF2485.jpg DSCF2483.jpg DSCF2811.jpg DSCF2323.jpg DSCF2813.jpg
     
  5. Sixy GMC

    Sixy GMC Junior Member

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    The engine swap is happening at Scott's place. Note the original and rusty '70 Z28...Scott bought it for $2,500 when he was a HS senior in 1982. It runs GREAT!
     
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  6. CorvairGeek

    CorvairGeek Full Access Member

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    I see add-on A/C on your truck too.
    Too bad about the manual brakes though. I knew someone that bought an '85 C10 long bed new in Daytona Beach with the base 4.3V6 with automatic (T400) PS, tinted glass, A/C and radio, but manual brakes as well.
     
  7. AuroraGirl

    AuroraGirl Supporting Member Supporting Member

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    It sucks the only inline 6 i have are a ford 300 in a f150, an oliver tractor, a stovebolt from a 50s gmc, a 40s dodge but no 250. closest i have is the radiator mount for a 76 nova with a 250
     
  8. Sixy GMC

    Sixy GMC Junior Member

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    Corvair...the add-on A/C is already out...it didn't work very well and took up a large amount of interior space...I'd rather use the vent windows and flow-thru vents.
     
  9. Sixy GMC

    Sixy GMC Junior Member

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    Aurora...my other classic Chevy is a '70 Camaro with a factory 250 6-cylinder engine with a 3-speed manual (floor shift). It has manual steering and manual brakes and it was a radio delete car. It stops fine with the manual brakes and has plenty of acceleration. I believe it may be the only '70 Camaro left with this drivetrain. It was sold new at a Los Angeles Chevy dealership and spent 31 years there, and as a result it has very little rust. My son Alex is in the 2nd photo...he absolutely loves classic Chevys (and classic rock :). The gas station is on state hiway 98 just north of the village of Waldo, OH. The station dates back to 1929 and it has been preserved by its original farm family who operated the station to augment their dairy farm income.

    I think it's great that at your young age you have so much appreciation for 6-cylinder powered vehicles. You have an impressive collection of trucks with sixes. I am always looking on Craigslist for interesting Chevys with 6 cylinders, and I have found quite a few in the past 35 years. They are superior vehicles in most respects and generally get much better fuel economy than V8s (many will probably interject their comments about this, but the 6 gives quite a bit better economy and has excellent longevity). I believe a lot of the fuel economy advantage is derived from driving at a more relaxed pace (V8s have much better acceleration, and most drivers use that advantage. DSCF9214.JPG

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    Last edited: Oct 17, 2020 at 10:11 PM
  10. AuroraGirl

    AuroraGirl Supporting Member Supporting Member

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    I mean, I Do have a lot of them but that caries a big *

    Such as the front end ofthe gmc is currently holding up part of a shelf.
    One is sitting in despair
    One is driving(f150), but its a ford...
    The tractor is a lawn ornament lol
     
  11. idahovette

    idahovette Full Access Member

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    Alex, your Camaro is the same color as my 70 LS6 Chevelle. Code 43 Citrus Green. RPO on Novas and Camaros, but it was special order on my car ($100.10 extra)
     
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  12. Sixy GMC

    Sixy GMC Junior Member

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    Perry...I have never seen a Citrus Green LS6 '70 Chevelle...an awesome car in an awesome color. I believe my car was a dealer "loss leader"...cheapest available Camaro that the dealer could advertise in the newspaper as "New 1970 Camaros as low as $2,395!". When the prospective buyer showed up, he or she would be shown the stripper and would be told that for an extra $116 they could have a V8, and for another $135 they could have an automatic. The original owner was a woman who drove it for 29 years in LA traffic with no automatic, no power steering or brakes, and no radio.

    As for the stepside project, we're having a couple of minor issues with the 3-on-the-tree column...it is not wanting to shift smoothly and is requiring a little bit of reworking to get it to shift properly. The column will be a combination of the original '83 truck column and a '69 Firebird column...there are a couple of minor differences that are causing the problems.
     
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  13. AuroraGirl

    AuroraGirl Supporting Member Supporting Member

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    i think a big problem is youre using a pre-collapse column maybe? well, together anyway. perhaps clearance with dash or cable lengths
     
  14. Sixy GMC

    Sixy GMC Junior Member

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    Thanks for the tip, Taylor. It actually is a collapsible column (first used on Pontiacs in 1967). The problem is the rod that goes from the key down to the ignition start switch is a different length due to the switch being positioned higher on the column than in '83. I am modifying the rod length to get it to reach the switch. I have already moved the turn signal switch and associated wiring harness to the Frankenstein column and all the electricals work. I think the truck will be operational today. I will still have to drive it to the nearby Midas store to have the exhaust system built from scratch. I have the very rare front pipe for it, but the rest was removed during the switch back to a six. All of the original exhaust mounts and the original cat converter mount and heat shield are still in place.
     
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  15. AuroraGirl

    AuroraGirl Supporting Member Supporting Member

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    i would personally think this would be a cool column. brights,turns are on the stalk as well as cruise button. but shifter is on the floor so it would be good for a manual and its tilt and its cool lol

    Snapchat-599433894.jpg
     

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