1. HemiTM

    HemiTM Well-Known Member

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    Need a little help. I am getting ready to put together my 8.75. It will be connected to a mildly built 318 and reverse valve 904. It will be seeing the track more than it will be cruising the blvd. Should I go with the 3.55 or the 3.91?

    Thanks
     
  2. 340plot

    340plot the bushy bush

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    i would think with a 318, i would go with the 3:55, even if you drive it once in a while on the street. i have a 340 and have 3:55 cause it will be on the street everyday, but 3:91 may have that 318 screaming.
     
  3. 3forty

    3forty "Raw Power"

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    How tall are your rear tires?
     
  4. 67valiant 100

    67valiant 100 go fast or go home

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    I'd go with the 3.91s because the little 318 is an engine that can rev. Also because you plan on racing it more than cruising in it.
     
  5. HemiTM

    HemiTM Well-Known Member

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    I will be using 255/60/15 tires
     
  6. 3forty

    3forty "Raw Power"

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    If it was me I would go 3.91s with the tires you mentioned in your post.
     
  7. MtNemoMopar

    MtNemoMopar In the doghouse

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    I run 275-60's and a four speed with 3.91's. It's fun, but I would rather have 3.55's. The rpm's get annoying on longer trips.
    For the track, the 3.91's would be better.
     
  8. stroked 340

    stroked 340 Banned

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    3.91's...........
     
  9. 440-VS

    440-VS Well-Known Member

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    3.91's if primarily on the track. Like MtNemo said, 3000 rpm's at cruise speed gets old.
     
  10. CUDACOX

    CUDACOX Well-Known Member

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    That is the same size tires I have with 391's. I rev 3 grand at 60 mph. Hope this helps. Craig.
     
  11. 1970Duster

    1970Duster Well-Known Member

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    In a 8 3/4 get both. One for track (3.91) and one for street (3.55).
     
  12. '64 Cuda

    '64 Cuda Well-Known Member

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    The 3.91 gears are a bit hard to live with day to day but for mostly track use I'd run them.
     
  13. Kevin Jonker

    Kevin Jonker Well-Known Member

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    Yeah 3:91's. You can still drive them around town no problem. Thats a 27 inch tall tire also. Try 25.5 inch tall tire with 4:56 gears....
     
  14. RustyRatRod

    RustyRatRod Weenie idiot loser. FABO Gold Member

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    3.23
     
  15. daredevil

    daredevil Well-Known Member

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    3.91 and an extra set ot 235 75 15s for the rear if you gotta road trip it. easier to change tires than gears. 318 likes low gears as well as any other small block. SS, 3.23,be real. never been a race gear unless you got gobs of torque.
     
  16. cudaspaz

    cudaspaz Well-Known Member

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    3.55's or maybe 3.73's?

    I'm thinking 3.91's would be sweet but yeah the RPM's will annoy the hell out of your road trips specially when some idiot in a supra wants to race at highway speeds.LOL.
     
  17. 66dartman

    66dartman Well-Known Member

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    How about 4.30's? My bracket 318 which I drove to the strip struggled even with 4.30's. 60' times were in the 1.90's. Don't take me wrong, I love that 318, it just needs all the help you can give it on the low end. If you are going to race the car, consider 4.88's. Seriously.
     
  18. RustyRatRod

    RustyRatRod Weenie idiot loser. FABO Gold Member

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    I guess if all you've ever built are engines that can't pull a greasy string outta a cat's ass then that's true.
     
  19. furz4

    furz4 Well-Known Member

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    I would go with 3.91 for a mostly track car. Had them in a Dart with a mild 318 build before. Good for stoplight to stoplight or at the track, any thing more then a little street driving tends to get old in a hurry. Good gear for a shorter tire but I always felt for street use I should have an overdrive with them. Stroker isn't that far off. I changed to 3.23 and lost 4 tenths but MPG went from around 10 to almost 17 and I could drive my car anywhere then.
     
  20. daredevil

    daredevil Well-Known Member

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    yeah youre right
     
  21. Rice Nuker

    Rice Nuker Let the Coal Roll!

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    3.91s are great for occasional blvd pounding. I had a coronet with 3.91s and it was a great in town cruiser / weekend strip car. You will be spinning 3500 - 4k at 75mph right? Thats tolerable for occasional cruise and smoking some Mercedes from light to light. I only got tired of the rpms on the freeway.
     
  22. fishy68

    fishy68 Tyr Fryr's Inc. FABO Gold Member

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    The 318 is a high rpm screamer so I'd go with at least 3.91's if not lower since you said it's mostly for racing. If it were for the street I'd say 3.55's.
     
  23. cudaspaz

    cudaspaz Well-Known Member

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    Oooo, I just got that visual.:toothy10:
     
  24. HemiTM

    HemiTM Well-Known Member

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    Bump
     
  25. HemiTM

    HemiTM Well-Known Member

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    3.91`s are in. Should be hitting the strip next weekend.
     
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