10 Years with a Turbo 200-4R

Discussion in 'The "Juice Box"' started by knucklebusted, Jan 24, 2021.

  1. knucklebusted

    knucklebusted Well-Known Member

    It popped on FarceBook that I got my 200-4R in my 70 Stage 1 car in 2011. A few things I've noticed or learned.

    1) A vacuum operated lockup switch is too touchy with anything more than a tight converter, in-out-in-out
    2) Even with 3.73 rears, I like the lower 1st gear
    3) Gas mileage improved about 1 MPG BUT the RPM dropped significantly, by 1/3, 3,000@60 is 2,000@60
    4) Lockup is more like a 5th gear with my 2,200-ish converter below about 2,500 RPM, hence 1 above
    5) I gave up racing well before this change since I broke two well-built T400s with nitrous (no N2O now)
    6) It is still going strong
    7) I wish I'd done it sooner
     
    chrisg, bobc455, Mark Demko and 2 others like this.
  2. Mart

    Mart Gold level member

    ^^ O.D. Best upgrade for a 70's car, with cam & gears, imo.
     
    Dano and knucklebusted like this.
  3. Ken Warner

    Ken Warner Stand-up Philosopher

     
    knucklebusted likes this.
  4. techg8

    techg8 The BS GS

    Stockish upgraded with hard parts or pro built 2004r ?
     
    knucklebusted likes this.
  5. knucklebusted

    knucklebusted Well-Known Member

    A local KY racer that has a transmission shop built it to handle 500hp. I'm not 100% what went in it but has has decent internals. Shifts firm.
     
    techg8 likes this.
  6. philbquick

    philbquick Founders Club Member

    Glad that's working for you. If you change the metering rod spring in the carb your fuel mileage will get better. When you run lower RPMs in overdrive it bogs the engine more lowering vacuum. The carb thinks the engine is under more load then it really is and raises the metering rods for more fuel. Of course you don't need that extra fuel cruising in overdrive.
     
    knucklebusted likes this.
  7. knucklebusted

    knucklebusted Well-Known Member

    Good to know. You are speaking of the spring that sits under the this primary rod hanger, correct? Would it also be called the power piston spring?

    Next time I'm in the carb, I'll look to see if I can identify the one I have. I had mine built by Quadrajet Power and it doesn't list the metering spring. Primary rods are .043 with 75 jets. I'll ask Mark about shortly.
     
  8. philbquick

    philbquick Founders Club Member

    That's the one.
     
    knucklebusted likes this.
  9. LARRY70GS

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

    I would put a vacuum gauge on the motor and tape it to the windshield. Then drive the car in overdrive and see where the vacuum actually is. An air fuel gauge would be even better.
     
    chrisg and knucklebusted like this.
  10. philbquick

    philbquick Founders Club Member

    I like that idea, a bung with an O2 sensor and a rich/lean gauge would really help to tweak it in. They make those springs for different levels of vacuum so the vacuum gauge will let you know what you're shooting for. I'm sure you'll get it closer but to get it perfect you need an ECU but that's a whole different system.
     
    knucklebusted likes this.
  11. LARRY70GS

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

    knucklebusted likes this.
  12. Matt69olds

    Matt69olds Well-Known Member

    Give the engine what it wants, not what you think it needs!!

    You don’t need a fancy A/F gauge, people did just fine for 70 years without those tools. Sure, it’s nice to have, but not needed.

    Keeping leaning out the mixture until you get a lean miss at part throttle cruise. This is much easier if your using a Q-Jet with an APT screw, if not, then it’s metering rod and jet changes.

    Once you have found the lean miss mixture threshold, go just rich enough to eliminate the lean miss. Then you can play with the spring rate.

    I spent a few weeks fiddling with 850 edelbrock Q-Jet. I kept leaning out the mixture until I ran out of adjustment, then went a jet size or 2 leaner then ran the screw all the way up again, and starter leaning it out again. With the 455, 3.73 gears, and gear vendor the car ran 11.70s and would get almost 18mpg easily.

    I drove the car like that for years. I did get a Innovate A/R gauge a few years ago, part throttle cruise would be in the 15.5-15.7 range. People would see that and freak out, saying it was too lean and I was going to melt pistons . At cruise, the engine is under very light load. Things won’t get nearly hot enough to damage anything.
     
    knucklebusted likes this.

Share This Page