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  1. #1
    Join Date
    Apr 2005
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    Default Best way to adjust TH350 shift points?

    I have a TH350 behind my mildly cammed 350 - has been rebuilt with shift kit but still shifts early thru all gears like a stocker. Installed a B&M adjustable modulator, which should be good for 2-3 mph upward adjustment but should I ultimately be considering a governor replacement or recalibration kit?

    Governor is likely original to the trans but not seemingly faulty.
    scott

    '72 Skylark Custom ragtop
    '72 Skylark (the band) greatest hits CD

  2. #2
    Join Date
    Jun 2007
    Location
    Connecticut
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    2,352

    Default Re: Best way to adjust TH350 shift points?

    TCI sells a nice governor recalibration kit with weights and springs.

    Lighten up the weights at 1st, then fine tune with the springs.
    Ken G
    www.everyday-performance.com
    on Facebook

    NE GS/GN
    83 Olds Cutlass (w/78 Buick 231 TURBO)
    72 Skylark 350 w/ Nitrous (12.87 @ 104.79 on 100 shot) SOLD
    "My mule dont like people laughin'..."


  3. #3
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    Apr 2005
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    Default Re: Best way to adjust TH350 shift points?

    Saw that on Summit's website.

    Looks interesting as I find out more about how it works.
    scott

    '72 Skylark Custom ragtop
    '72 Skylark (the band) greatest hits CD

  4. #4
    Join Date
    Jul 2006
    Location
    bowling green, ky
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    1,619

    Default Re: Best way to adjust TH350 shift points?

    B&M also sells a kit, part number 20248. I have used this kit twice and it did what I wanted. Both Jegg's and Summit sell them but you might not see them in their catalog, just ask the sales person on the phone.
    1984 Regal race car (ZZ430 clone motor) 11.671 @ 115.27 mph (sold)
    1985 Regal, 231 V6
    1975 TR 7, 238 V6 Buick, 14.10 @ 93.97 mph (sold)

  5. #5
    Join Date
    Apr 2005
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    Tampa, FL
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    486

    Default Re: Best way to adjust TH350 shift points?

    Yup - 20248's on Summit's website too - both kits look pretty well suited for what I'd want if they work on shift points below WOT.

    I'm running 3.23 gears now and I think the transmission was already set up for 3.08 - it's the original mate to my '70 SP motor.

    Right now it shifts at just about the same points as the stock '72 I pulled from the car (which had last been rebuilt in the 80's from what I can tell).
    scott

    '72 Skylark Custom ragtop
    '72 Skylark (the band) greatest hits CD

  6. #6
    Join Date
    Nov 2010
    Location
    Simi Valley, CA
    Posts
    2,628

    Default Re: Best way to adjust TH350 shift points?

    You can put the shift a little later by adjusting the detent cable at the carburetor; also by adjusting the modulator, if you have an adjustable one.
    '68 Buick Skylark California GS
    '00 Chevy Astro Van
    '70 Chevy 3/4 Ton Longhorn Custom Camper, numbers matching

  7. #7
    Join Date
    Mar 2010
    Location
    Arlington, TX
    Posts
    303

    Default Re: Best way to adjust TH350 shift points?

    Quote Originally Posted by SteeveeDee View Post
    You can put the shift a little later by adjusting the detent cable at the carburetor; also by adjusting the modulator, if you have an adjustable one.
    So....do you introduce more slack into the cable to make the car shift later? You can't make the cable pull any sooner (tighter), otherwise it will prevent the throttle plates from opening completely... can you expand on this a little? I have the same problem with my TH350.
    Thanks.
    David

    '64 Skylark Convertible 300/355 Wildcat TH350 Trans

  8. #8
    Join Date
    Feb 2002
    Location
    Oakland Gardens, N.Y.
    Posts
    21,451

    Default Re: Best way to adjust TH350 shift points?

    Wide Open Throttle upshift RPM is controlled by the governor. The vacuum modulator will only give 2-3 MPH on the minimum and part throttle shifts. Forget the detent cable, it is self adjusting at the gas pedal. Buy the B&M or TCI kit and start testing until you get what you want.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  9. #9
    Join Date
    Jun 2009
    Location
    Canandaigua NY
    Posts
    216

    Default Re: Best way to adjust TH350 shift points?

    I took a dremmel to the stock weights (ends and sides at the end), started conservative until I got the shift points to where I wanted them (4900-5000). It took a coulple of times to get it where i wanted. I was running a stock 100k mile 455 at the time.

    I took the governor apart so I would not get any filings in the sensitve parts. I did buy a kit but I only used the replacement pins that secure the weights. I cleaned everything and put it back together. I read that the governor is sensitive to dirt.

    Also I noticed that when I built the new motor (425-435 horse) and added the 3200 stall converter the shift points changed to 5200.. It ended up being perfect. Guess I'll soon see what the rebuilt tranny with the b&m shift kit does to the shift points...

 

 

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