Cooling System + Timing Questions

Discussion in 'Engine/Drivetrain' started by Olds77421, May 8, 2023.

  1. Olds77421

    Olds77421 Member

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    I have two separate issues I'm trying to get more info on and have come up dry looking elsewhere online:

    1. Does anyone have a total timing spec for a 20R? I know the factory spec is 8* BTDC at idle (850 RPM) but what is everyone running for total timing? I'd guess it's around 28-32* BTDC @ 3000 RPM but cant find any info anywhere else online.

    2. Can anyone confirm the cooling system diagram for a 1976 20R pickup? Im in the middle of a Vintage Air install and can't seem to get a handle on routing. The diagrams online aren't all that helpful and a lot of the pics from earlier forum posts are missing. Right now I have it as:

      --The line off the bottom driver side of the radiator >> heater core inlet
      --Heater core return hose (hose through firewall on passenger side) >> thermostatic valve on head
      --line from top of intake >> tube under manifold that connects to the water pump
    Just want to make sure I didn't get the routing all backward.
     
  2. fred heath

    fred heath Addict

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    The 8 degree before mark was intended for pollution control engines. Unless you’re running a completely original, stock engine with all smog devices attached that number is not accurate.

    I’m running 10 before with a Weber 32/36 and no smog. You need to experiment with different settings. If your distributor has an octane meter attached you can fine tune the advance there also.

    Forget the factory specs. Experiment until you got a good running engine.

    I have the FSM for the 20R engine. I’ll try to grab the coolant flow diagram tomorrow.
     
  3. Olds77421

    Olds77421 Member

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    Im currently running with smog delete, a Holley Sniper 2300 EFI, and an MSD box with a magnetic pickup distributor. Im assuming 10-12 base + 32 total around 3000 would be a good ballpark to start, but was curious to see if anyone had a similar setup and what they were running.

    Any info on the coolant hose routing would be greatly appreciated. Basically just need to know what side of the heater core on the factory setup was an intake and what was a return.
     
  4. jetas

    jetas Grand Toyotaholic

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    [​IMG][​IMG]
     
    Last edited: May 8, 2023
  5. Olds77421

    Olds77421 Member

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    Looks like the image is missing.
     
    jetas likes this.
  6. jetas

    jetas Grand Toyotaholic

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    Flow is the same on the 22R.
     
  7. Olds77421

    Olds77421 Member

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    Thanks. Looks like I done goofed and got it reversed. The hose off the thermostatic valve is the send on the heater core side and the hose that goes to the radiator is the return.

    This is super helpful.
     
  8. jetas

    jetas Grand Toyotaholic

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    The lower rad hose is the in to the engine. Top hose is the out of the engine
     

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