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4,000 or 5,000 rev tach?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer_Boy, Feb 27, 2001.

  1. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Thinking about getting an autometer tach and thought what in the heck do I need an 8,000 or 10,000 rpm tach. They make a 4,000 or 5,000 low rev tach and was wondering what i should get. '82 K5, stock crate 350, 700R4, NP208, 31" Michelin AT's, 3.08 diffs (uprgrading to 3.73s). I'm pretty much a city/highway boy with a litte off-roading every few months.

    Two lanes wide, twelve yards long, sixty-five tons of American pride....Canyanero!
     
  2. fastzilla

    fastzilla Registered Member

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    I think most gassers redline around 5400-5500 rpm.... Depends if you care about the last few 100 rpm. FYI gages are most accurate in the middle of their range. ie 8k tach is most accurate at 4k. If you run around between 2&4k most of the time the 5k tach will be most accurate. If you rev redline alot the 8 or 10k tach would be best because you need the most accuracy around 5k to keep from blowing your engine...
    Eddie
     
  3. Smitty

    Smitty 1/2 ton status

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    I've been looking for a good 5,000 RPM Tach. Do you happen to have the part number? It just hasn't made sense to me to get an 8,000 or 10,000 RPM tach and watch the needle move a whole inch. I'm only pushing around 3,000 at 60 mph. I didn't put this one together and don't know who did so it won't be seeing any real high numbers.

    Smitty
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    I'll do you one better and show the page from autometer. [​IMG] (there under the street perfomance series)
    Model Number 2890 / Model Number 2891
    [​IMG]

    Model Number 2697
    [​IMG]

    I guess Im still trying to decide between the 5,000 and 4,000 one now. The previous post stated that tachs are most accurate in the center and i'll be running a little over 2,000 probably for the shifts, it makes sense. I'll probably never crack 3 in my life so I'm shying away from the 6,000. I dunno, 4,000 just doesnt seem like enough range even though i wont go that high.


    Two lanes wide, twelve yards long, sixty-five tons of American pride....Canyanero!
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK I know this post is old, but I just read it now, I've been gone for 2 weeks. (I'm 23 pages back right now [​IMG])

    I have an 8000 RPM tach in my Jimmy. My 350 will pull 5400 RPM, I just don't like to do it often. If you think you'll never let it rev above 3000 RPM you are fooling yourself.......

    I think a good 6000 RPM tach is decent, but a 4000 RPM tach should be for deisel only.

    Just my opinion, but I want my tach accurate where I'm close to my red-line. My tach is 3 1/2" so the needle moves a lot.

    Rene

    [​IMG]
     
  6. POWERMAD

    POWERMAD 1/2 ton status

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    I have an old Sun tach that is 8,000, mounted on the column next to the speedo. It blocks it off up to 20mph.
    I normaly shift at 4,000 and take it to 5500 once in awhile.
    That old tach is still accurate, I've checked it against my Fluke.
    see ya

    my truck's not dirty, it's earth tone paint
     
  7. Thumper

    Thumper 1/2 ton status

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    Well, I said the same thing as you did. "I will never go above 4000". But I got the 8000 tach in and glad I did. With the 4:56s and the 327, in 4lo in the mud, I normally end up around 5000. Even with an auto, say you want to get thru an intersection in a hurry, it probably wont shift until 4000. I cant remember if you had a std or auto, but I suggest the 8000 one. Just my opinion.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Lets Go Wheelin! </font color=red>
     
  8. Wheels

    Wheels 1/2 ton status

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    Just a word of caution. Most stock harmonic balancers are rated to 4600 RPM's. After that, heat builds up quick and they will slip on the rubber ring in them. If your going to rev much above that for periods of time, get a performance after market dampner. (from a lesson learned he hard way)
     

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