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81 C20 Build Log

Discussion in '2wd Pick-Ups C/R 20 2500 C/R 30 3500' started by Pancake_Turtle, Mar 24, 2020.

  1. Pancake_Turtle

    Pancake_Turtle Junior Member

    Posts:
    25
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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Not really sure where I am going with this Truck but I am going to document the journey of repair and modifications.

    20200124_150853.jpg

    I have a 1981 Chevrolet C20 Scotsdale

    View attachment 141757

    20200315_180536.jpg
     
    Craig Nedrow and FireTruck1984 like this.
  2. Pancake_Turtle

    Pancake_Turtle Junior Member

    Posts:
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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Not entirely sure what I am doing, First legit Forum activity and build log. Any pointers would be great

    I know the 305 is the less desirable engine, but I want to make it more reliable for the time being. I dream of putting something like an LS in this one day but the 305 will suffice for now.
    Most of my short term plans are meant for reliability and some cosmetic changes.

    Things Needing Replaced:
    Brake Booster(Leaks really bad)
    Driveshaft Carrier Bearing
    Exhaust System needs put on(currently running a strange mock-up to be not straight headers)
    Something in the HVAC System. Have not had time to investigate. (makes a horrible squeal when you turn the air on)

    Small Things I am Replacing:
    Spark Plugs
    Wires
    Lug nuts (I had really bad tires on my factory rims, I managed to get some take offs that are in the picture above, but to use the center caps I need to change the nuts so I can screw them on)
    I have an Engine Dress up kit to install for fun.

    Any questions or things I should do first? this is my first Square Body.
     
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  3. HotRodPC

    HotRodPC Administrator Staff Member

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    Joined:
    Aug 29, 2010
    Location:
    OKC, OK
    First Name:
    HotRod
    Truck Year:
    85 K20 LWB / 86 K5
    Truck Model:
    Silverado / Silverado
    Engine Size:
    454 - Turbo 400 - 3.73 350 - 700R4 - 4.10
    Not a bad optioned truck. 3/4 ton with OEM 305, Auto and 3.42 Locking Rear Diff. So it's a 14 bolt Semi Float rear axle. A great gear ratio to have for a non overdrive auto transmission.
     
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  4. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Oh thanks for the info, I hadn't figured that out yet.

    Just found out that the Transmission is a rebuild and I have another auto that is freshly rebuilt. I read your Trans rebuild Thread and wonder myself if I have the better internals, I will see what the tag says in a bit.
     
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  5. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Update 1

    The transmission I have sitting in my garage doesn't appear to have the tag identifying it. but I did notice it has the short tail shaft so I would need to change that or change my driveshaft to use it if I am not mistaken. I am probably blind and am just missing the tag. here are some pictures of it. I tried asking my friend Google about that casting number, C8U166004 but I didn't get any results.

    20200326_190021.jpg

    20200326_190030.jpg

    20200326_190048.jpg

    20200326_190056.jpg

    20200326_190105.jpg
     
  6. Pancake_Turtle

    Pancake_Turtle Junior Member

    Posts:
    25
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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Update 1.2

    My belts are all stretched and old. while looking to change my spark plugs and wires I noticed my belt adjustment was MAXED out for the AC belt. I had already purchased some belts from O'Reilly's and I think I have the wrong ones.
    I am having a difficult time finding what I need.

    Belt that was on the Alternator, Air pump, Fan, Crank? was a Napa Premium XL 25-7490 with a bar code of 83165D8L 20 the dimensions are OC 49.57" depth of 7.94
    20200326_185514.jpg
    Belt I was sold was a MasterPro 7405 15405 3/8" x 41" OC or 10mm x 1042mm OC
    20200326_185343.jpg

    I called Napa up to ask them if this was the correct belt and the Napa Guy said no it was too long. so I am confused on what I need as far as my belts.

    the belt on the A/C, Power Steering, Crank? is currently a BANDO RDP 6565 11x1435La from the picture I took 20200326_185808.jpg

    From Driver Side.
    20200326_185912.jpg

    20200326_185808.jpg

    20200326_185514.jpg

    20200326_185343.jpg

    20200326_185912.jpg
     
  7. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Joined:
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    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Update 1.3

    The other belts I have for this are all MasterPro, a 7480 15480 3/8" x 48-3/4" and a 7448 15448 3/8" x 45-3/8"
     
  8. RoryH19

    RoryH19 Full Access Member

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    Joined:
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    Location:
    Texas
    First Name:
    Rory
    Truck Year:
    1987, 1982, 1983
    Truck Model:
    R10 Silverado SWB, K5 Silverado Blazer, K5 Silverado Blazer
    Engine Size:
    350 TBI, LS Swap 6.0, 350 carb
    Welcome
    From your pics, it looks like you have the original brackets and accessories. Parts stores should be able find the right ones. You can also try a size smaller if too large.
    The trans on the ground appears to be a TH350 from what I can see. The pan is the easiest way to tell.

    As for the truck I think you have the right idea. Take care of all the maintenance items; plugs, wires, brakes, fluids, tires...

    While the LS swap is popular and provides a reliable drive train it's not as easy as people make it out to be.
    If you want to go that direction plan and research as much as possible first.

    Good luck.
     
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  9. Pancake_Turtle

    Pancake_Turtle Junior Member

    Posts:
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    Joined:
    Jan 24, 2020
    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    TH350 okay cool, I don't know anything about that one so Its time to research some more.

    I tried that and the belts I got don't seem right

    I believe at least 90% of it all is stock.

    That is a long time down the road, just thoughts and prayers at this point. It is much more likely that I will pick up a 350 and do something with it.
     
  10. RoryH19

    RoryH19 Full Access Member

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    Joined:
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    Location:
    Texas
    First Name:
    Rory
    Truck Year:
    1987, 1982, 1983
    Truck Model:
    R10 Silverado SWB, K5 Silverado Blazer, K5 Silverado Blazer
    Engine Size:
    350 TBI, LS Swap 6.0, 350 carb
    I like to use gates belts, may be worth a try.
    You can also measure with a string around the pulleys for each belt. If you're not able to use the recommended one.
    A 350 with TH350 is a very reliable combination and parts are cheap.
     
  11. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    I asked for the one I needed and I got 3 different ones ha this is why I am in a conundrum on what belts I need, I like Gates belts too will probably chase those down.
     
  12. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Joined:
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    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Update 2

    Figured out the belts I needed! I went with Gates all are 10mm size

    I needed a 7405, 7480, and a 7555

    the 7405 was for the Crank to Power steering pump on the space closest to the block

    the 7480 was for the Alternator, Air pump/Smog, Fan, Crank on the second space

    the 7555 was for the Radial A/C, Fan, Crank, Power steering pump on the third space

    So if anyone else has a 305 with those options, those belts worked for me. I have attached a belt diagram cause I could not find one so I made one just for reference since the most popular answer to "hey I have a 305" is to "swap it for a 350" ha

    I changed 2/3 belts to make sure they were indeed what I needed and would fit but I could not figure out how to get the power steering pump to crank belt off. that belt is actually not in bad shape like the other two were so I am not worried about it yet.

    Now on to the Spark plugs and wires and an oil change tomorrow.

    305 Belt Diagram.png
     
    Last edited: Mar 28, 2020
  13. Pancake_Turtle

    Pancake_Turtle Junior Member

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    Joined:
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    Location:
    Ohio
    First Name:
    Gideon
    Truck Year:
    1981
    Truck Model:
    C20
    Engine Size:
    5.0 305 4BBL
    Update 3

    Changed all the Spark plugs today. man cylinder 8 was a major pain in the rear. not sure what vacuum valve was in the way, attached to the header/collector.

    Found lots of caked on oil/grime under my truck. Anyone know of a good method of cleaning that? is it safe to use a low psi Pressure washer? what would I need to tape off besides the distributor? anything on the heads? Can't wait to get the Air Pump crap removed, it was in the way in a major way. I think when I get my wires tomorrow I will look into starting removal of that hopefully. Wish me luck ha
     
  14. Craig Nedrow

    Craig Nedrow Full Access Member

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    Joined:
    Sep 1, 2018
    Location:
    Washington State
    First Name:
    Craig
    Truck Year:
    1973 (have two)
    Truck Model:
    K10 and k20
    Engine Size:
    350
    Love the truck. In my area, (Central WA ST), Craigslist SB, and BB are abundant and cheap. I am just ready to swap my circle track motor out of my K20, to a 454 motorhome motor. 1500.00 on Craigslist. I put another 1000.00 in various parts, ( new intake, dipstick and tube, fittings, bolts, poly motor mounts, paint, trans seals etc.) Just a thought. IMG_2479~photo.JPG IMG_2479~photo.JPG
     
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  15. idahovette

    idahovette Full Access Member

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    71
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    Joined:
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    Location:
    Weiser Idaho
    First Name:
    Perry
    Truck Year:
    1975-1979
    Truck Model:
    K20-K10
    Engine Size:
    350
    Nice THICK header flanges!! Good for you
     

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