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700r4 conversion

Discussion in '1960-1966' started by raking, Jan 31, 2009.

  1. raking

    raking Member

    I have a 1965 C10 swb truck. I would like better fuel economy from the 1972 350 with 350 turbo from a 1972 Monte Carlo(3.43 rear end). I have been exploring 700r4 trannys,aftermarket overdrives and 3.08 rear gears. any suggestions as the best way to go. the truck is used for cruising and not a lot of towing. While driving down the highway it seems I need another gear. Thanks for your input. raking
  2. dvalentine

    dvalentine Charter Member

    The 700 R4 is the way to go ! I used 373 rear ratio and still averaged 19 mpg with a PANEL TRUCK !! Freeway milage was 21-22 mpg.

    The 373 ratio allows better "feel" on surface street driving, good launch and normal shift ranges. 308 ratio rear may make it feel sluggish for street surface driving causing you to step into the throttle more, which is what you don't want for milage purposes.

  3. raking

    raking Member

    Thanks a lot. I'm glad I found this forum. Is the TV difficult to adjust? How do you think the 3.43 will perform?
  4. dvalentine

    dvalentine Charter Member

    In a word ?? YES..
    but only if you want it done correctly so the trans does'nt melt down in the first few miles of operation !!!
    I had mine adjusted by a trans shop after I installed it, and took it there on a flatbed.

    Read TV101 on this site: http://www.700r4.com

    343 will be better than 308's in my opinion...

  5. Pontiac1976

    Pontiac1976 Member

    I heard some Pontiac guys useing 3.23 gear with the 700R4 but there lighter then a truck for the cars you would not want to go lower then that with a car.
    I beleave 3.43 or right around that is the lowest gear for the 700R4 to work best not hurt gas milage. In a truck
  6. drabo

    drabo Member

    You will see a huge diffrence with a 700R4 swap. A couple things to keep in mind the driveshaft needs to be shortened. You will need a TV corrector bracket if using an aftermarket carb. An additional tranny coler is a must even if you have a automatic radiator. Also need a new mount and tranny crossmember www.classicperform.com . www.bowtieoverdrives.com is a good source for ideas on what you need. Shop around for your parts BTO is pricey. BTO also has a good speedo calculator for getting the right speedo gears.
  7. raking

    raking Member

    i'm currently using the original quadrajet carb but thought in the future I might go with an edelbrock carb to se if performance and mileage improve. Anyone use this? if so does it really help to get the intake carb combo or does the stock intake work just as well?
  8. verdell

    verdell Member

    I'm running a stock 350 w/ 700r4 and 3:08 rear....changed over to a edelbrock carb and intake..there was a noticable difference in performance..btw switched over to an electric fan which helped also..
  9. Rich 5150 69

    Rich 5150 69 Member

    Note if using the rear motor mount holes, so that the distributor is close to the fire wall, you`ll have tranny / body interference at the seam that is on the lower portion of the firewall, some trimming may be necessary.
  10. drabo

    drabo Member

    I used a body pannel adjustment tool (hammer) to correct this problem.

    Aslo I am using the performer/performer combo. There was a big diffrence. I am getting a more complete burn and less black soot.

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