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350 HO from gmgoodwrench

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Dunc03, Jul 17, 2002.

  1. Dunc03

    Dunc03 1/2 ton status

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    I am replacing my 86 305 with a the 350 Ho from gmgoodwrench. I have heard a number of times that the flexplate has to be change in some applications. My motor came with a one piece rear main seal, and I know that flexplates differ between the one piece and two piece rear main seal. IF my flexplate is alreay matched up to the one piece, will I still have to buy a different flexplate for the new motor being that it is a one piece too. And while I'm asking will the harmonic balancer be the same. Once again thanks for the help and info.
     
  2. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    It will most likely work. but I have heard that 86 motors were way weird in that regard.
    IMO it would not hurt to get a new flexplate. It is a good time to change it and with a new motor, I say go ahead. It doesnt cost a whole lot. It is cheap insurance. That new motor will have a lot of new found power.

    My .02,
    John
     
  3. ramjet gmc

    ramjet gmc CK5 Staff Staff Member Moderator GMOTM Winner

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    My 86 305 had a 2 peace main seal I had to but a new flywheel for a 1 peace
     
  4. Dunc03

    Dunc03 1/2 ton status

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    The only conformation I have on an 86 having a one piece is this site, so it is very possible that I'm wrong. I think I will get the flexplate now, that way I won't have the headache later, thanks for the info.
     
  5. sosamantx

    sosamantx 1/2 ton status

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    i'd say that the flexplate will work (since it is a 1 piece rear main seal). but, the harmonic balancer will not work!! i thought it was because of a balancing issue, but from what i've read, it's a timing mark issue, i think it's like 45 degrees off (something like that).

    http://www.sallee-chevrolet.com/Discus/board.html <-- good message board!!

    http://www.sallee-chevrolet.com/Discus/messages/653/2392.html?ThursdayMay3020021139am <-- not sure if this will work, but it's the thread about the timing marks that i was refering to. /forums/images/icons/wink.gif
     
  6. EDdaTREE

    EDdaTREE 1/2 ton status

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    Go to www.paceparts.com and look around. You can call the 800 number for the info you need. Check their prices for motors, too.
     

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