Question regarding running conditions after installing headers

Discussion in 'Street/strip 400/430/455' started by 70rivme, May 15, 2020.

  1. 70rivme

    70rivme Well-Known Member

    I am not quite there yet but I think I need some help. I have a mildly built 455 in my '70 Riviera that was running through manifolds and a stock style exhaust. The engine has very minimal run time as I had an oil pan leak that I wanted to take care of so one thing led to another and the engine has been out of the car for 1.5 years now. I will be getting this car reassembled hopefully in the near future except this time around instead of manifolds it will be running TA shorty headers into a 2.5" exhaust system. If the car ran good with manifolds for the short while before pulling the engine out, can anyone comment on what I can expect running it with headers and a 2.5" exhaust? Will there be noticeable power gains, will the timing and carb require tweaking? I'm running a 780CFM Quickfuel carb if this helps at all. The Turbo 400 will be rebuilt and more than likely include a JW 9.5 converter and be installed with the engine as well. Thanks for any input or suggestions, appreciate it!
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

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  3. TrunkMonkey

    TrunkMonkey Well-Known Member

    Cap'n Oblivious sez remember to prime that oil whirler a minute or three before you turn the big block music to 11.
     
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  4. johnriv67

    johnriv67 Well-Known Member

    With my 67 Riviera and it’s 430, it was stock running 14.69 @ 93.21.

    I put in a mild cam (219/238 .490/.453 lift), a 12” switch pitch converter, and the TA 2.5” exhaust with shorty headers. My time has since dropped to 14.02 @ 98.49 and there is certainly more left in it. Probably had 13.8s in it on good weather and traction days.
     
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  5. 70rivme

    70rivme Well-Known Member

    Good info, thank you! The man that built the engine supposedly rebuilt the distributor and worked all the magic that would make the distributor work with the engine/car. I guess we will see when I check it.
     
  6. 70rivme

    70rivme Well-Known Member

    This is now on the agenda before it gets put back into the engine compartment. Thanks for the reminder Cap'n Obvious!
    ;)
     
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  7. 70rivme

    70rivme Well-Known Member

    Nice!!! I take it you are pretty happy with your upgrades in the Riv?
     
  8. johnriv67

    johnriv67 Well-Known Member

    I was sort of happy, I then added another 100 horsepower in the form of ported Stage 1 heads, a much bigger cam, and an even larger quadrajet.
     
  9. RoseBud68

    RoseBud68 Well-Known Member

    Lol...Never happy.
     
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  10. johnriv67

    johnriv67 Well-Known Member

    If I can run high 12s, I will be happy. That means only two 2nd gen Rivieras are running 12s on the entire East Coast, to my knowledge.
     
  11. telriv

    telriv Founders Club Member

    I believe the other is Yardley.
     
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