Struggling a bit with tuning this fresh 289/302

Discussion in 'Ranchero Tech Help' started by Boiler92, Oct 15, 2021.

  1. Boiler92

    Boiler92 In Overdrive SILVER MEMBER

    Messages:
    608
    Location:
    Indiana
    Set timing at 6 deg BTDC with the vac advance disconnected and carb port plugged and it starts and runs but it sounds and runs better at 10 degrees BTDC. Pertronix II distributor. 2 bbl 2100 carb.

    Also, Assuming this el cheapo $28 gauge from Advance Auto is accurate, I'm only getting 15 inches of manifold vacuum at idle no matter how I fiddle with the mixture screws. Most of the vids I've watched on similar setups are getting 20+ inches.

    Are both OK or should I continue to mess with it?
     
  2. DJ Clinton

    DJ Clinton In Third Gear GOLD MEMBER

    Messages:
    201
    Location:
    Mesquite, NV
    On my 289-rebuilt the 2100 carb. I get 15-17 inches of vacuum, same as I did before the rebuild. I also tried the manual recommendation of 6 degrees BTDC (for a manual trans), ended up going back to 12 degrees and it runs much better. One thing, with the rebuilt carb, I can set the idle at about 800(1100 before rebuild).
     
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  3. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

    Messages:
    1,484
    Location:
    central CT
    Take it out for a test drive, and add timing until it pings, then check timing and back off a couple of degrees.. 6 is probably nowhere near enough. Idle vacuum will vary considerably depending on camshaft.
    Did you restrict the amount of mechanical advance? Best to have more initial and less mechanical.
     
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  4. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    1,600
    Location:
    Freehold NJ
    My 289 also pertronix ran best 10-12 advance. 17" steady at idle, 600rpm (stick).
     
  5. crab1

    crab1 In Second Gear

    Messages:
    40
    I'm at 15 degrees initial on my 351w and it runs great, the timing mark was slightly off on the damper and hadn't spun, corrected it with some timing tape.
     
  6. Boiler92

    Boiler92 In Overdrive SILVER MEMBER

    Messages:
    608
    Location:
    Indiana
    Thanks for the replies. Not so concerned now.
     
  7. lscmark

    lscmark In First Gear

    Messages:
    1
    Location:
    fox lake ill
    I've worked with many 302's over the years, most are happiest between 12-16 base, 35-40 all in
     
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