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78 C20 Silverado Camper Special build thread

Discussion in '2wd Pick-Ups C/R 20 2500 C/R 30 3500' started by thecantaloupeman, Jun 24, 2019.

  1. thecantaloupeman

    thecantaloupeman Full Access Member

    Age:
    20
    Posts:
    443
    Likes Received:
    139
    Joined:
    May 14, 2019
    Location:
    US
    First Name:
    Dawson
    Truck Year:
    1978
    Truck Model:
    C20 Silverado Camper Special
    Engine Size:
    350
    April 2020: Okay so we are finally caught up. I figured doing month by month would make things a bit easier to read and more organized. It also gives me a bit better sense of when I did things and shows the progression a little more. From now on I plan to be a bit more active on this thread so I don't have to keep doing that every 6 months. I might also update it later to include any pictures I have.

    -So my current project is the exhaust system. I got a nice new reciprocating saw and used it to slice off my stock rusted out muffler and I removed the old tailpipe. I ordered a new tailpipe for 26$ from walker and It works out perfectly. I decided to go with a Thrush Welded muffler to replace it. I already held it up to the pipe to see what it would sound like and I love it! Just the right volume and it sounds really nice yet tame at the same time so I won't wake the neighbors. And it was only 44$! Can't beat that! I was just going to use exhaust clamps but its been hard trying to find the right adapters and I recently sliced open my thumb on the old rusty exhaust clamp so I decided to just have the muffler shop weld it in. That way I don't need to worry about it falling off because I got the wrong size adapter and I can let someone else do it for me. I will post some pictures and video once they weld it in.
     
    bucket, Catbox and Craig 85 like this.
  2. 75gmck25

    75gmck25 Full Access Member

    Posts:
    1,158
    Likes Received:
    759
    Joined:
    Oct 13, 2016
    Location:
    Northern Virginia
    First Name:
    Bruce
    Truck Year:
    1975
    Truck Model:
    K25 Camper Special TH350 NP203
    Engine Size:
    5.7
    I have similar off-idle hesitation on my '75 K25, especially when its cold, and have been working a while to figure out what is not working right. I think its the Quadrajet idle system that doesn't transition right from near-idle to cruise mode.

    I have a digital AFR gauge and the Quadrajet runs quite lean at idle, (usually about 17, and then the AFR really goes lean at the time the hesitation occurs (about 20-21). I just moved my idle mixture screws out a 1/2 turn to see if that will help. Its one of those problems that's been hard to troubleshoot during colder weather. I've purchased two different accelerator pump assemblies, and it worked about the same with both.

    I have also found that with a warm engine the hesitation almost goes away if I bump up the timing. I'm running aluminum 64cc heads and a little more cam, and the engine runs well with about 15 degrees BTDC base timing and 20 more from mechanical advance. With a stock 350 you could run about 12 degrees BTDC, and might even be able to use more before it pings.

    Bruce
     

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