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1991 Vortec motor in a 1978 chevy pickup

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by RootBreaker, Aug 15, 2002.

  1. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    Ok well I got my motor pulled out last night..\
    I want to change over my fly wheel and it dont fit!!! WTF
    My truck has a SMC465 trans and the vortec block had a automatic 700R4.
    Anywho... My crank on my old motor looks like a mushroom where as my 1991 crank is completely round. they both have 6 bolt holes. I called our local parts store and tried getting a flywheel for a 1991 caprice manual but they say they cant get one and dont list one. Also if I choose to get one from a 1991 chevy pickup then it will be $150!!!!
    anyone know what I need??/?
    I got some researching to do!!!!
    http://68.45.68.102
     
  2. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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  3. HarryH3

    HarryH3 1 ton status Author

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    First, the Vortec headed engines weren't available until '95 or '96. 1991 just had a TBI engine, but it used a one-piece rear main seal. As you've found, the crank was changed to accomodate the new seal. You will need a flywheel that will go with the crank that you have in the new engine. I'd be surpised if a '91 Caprice was even available with a manual trans, but the flywheel from a truck, Camaro or Firebird of that year should work.
     
  4. HarryH3

    HarryH3 1 ton status Author

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    BTW, we can't see your pics. A prompt for a username and password pops up after the top picture on that page is displayed. /forums/images/icons/frown.gif
     
  5. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    hmmm.. I noticed that too... about the pics from remote locations...
    here...
    [​IMG]
    and this is the 1991
    [​IMG]
     
  6. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    What I was told is the motor is a 1991 Vortec Block 350 4 bolt hydrollic roller cam/lifter from a 1991 Caprice police car with package 9C1 ( Motor package )
    It has cast heads but vortec block rated at 260+hp. One option is to put vortec heads on and gain 40-50hp which I will be doing someday... I just gotta get he motor installed.
    Also here are the casting numbers....
    Block
    5.7 SGI G130 14093638

    Heads
    GM24 14102193
    Thanks for any help...
     
  7. JIM88K5

    JIM88K5 1/2 ton status

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    The Vortec heads are where the power comes from. The blocks are the same. As mentioned above, the Vortec set up started in 96. It looks like you have a TBI motor. I'll make a mental note and check it out at work in a.m.
    Jim
     
  8. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    yes it is a tbi motor. I am having my intake holes drilled off of my 78 intake so the 4 inner bolts will line up. I plan on doing this until later (when the truck goes on the road), when I get vortec heads and then buy a new intake. Since I am low on $$$$ now. Seems that I am going to need a new flywheel....

    thanks for the info on the 96.
    p.s. can people still view my pics by going to... http://68.45.68.102/PROJECT_NJLEGAL/htm/2002_b.htm
     
  9. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    oh yeah if it asks for a name/password just put in...
    administrator with no password.. dunno why it is doing this but works... /forums/images/icons/confused.gif
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah any one piece rear main flywheel (for a truck) should fit, which I believe will be any '86-up.
     
  11. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    I just did alot of research on it and that is what I have come up with..
    a 1986 and up truck/blazer flywheel will do.. It is just the $150 new price that is getting me.. I just dropped $300 in seals/cap/rotor/plugs/wires/rear main/etc... so the extra $150 is where it hurts.. dont have it but need to put the motor in this weekend... GRRRRR
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, I've got a couple of suggestions.

    First off, call some local machine shops. People drop stuff off and never pick it up, so they might have turned flywheels sitting on the shelf.

    If you have a little bit of time, hit automotive swap meets. I picked up a flywheel for $10. Then had it turned for $35. Heck of a lot cheaper than new : )
     
  13. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    true.. but the time part is where it is at... I need to get the motor in on sunday so I can get the yard cleaned up. Going to put the house up for sale and dont want it to look like Sanford & Son...
    hmmmm... what to do.. I have 2 guys that are supposed to call me back today if not i will just by the new one and be done with it...
    thanks for the info
     
  14. alec78

    alec78 1/2 ton status

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    A little know fact is that GM Vortec truck heads are the same as LT-1 heads. Combustion chamber CC may be the only difference. I know that the LT-1 came out in the 93 F-body and it was also in the 94ish B-body (Caprice, Impala, etc). I couldn't say for sure as Police models are a bit different, but I don't think they had them in 91.

    The easy way to id vortec/LT-1 heads is they have no center bolt holes for the intake. Also, if it is an LT-1 block there is an extra hole above the cam gear in the timing chain cover. This hole is for the water pump drive, since it had no belt drive.
     
  15. Blazer1970

    Blazer1970 1/2 ton status

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    LT1 heads are aluminum. Vortecs are iron. The combustion chamber design is similar but that is all. I don't think LT1 heads use the Vortec intake bolt pattern either. They use the typical TBI / TPI pattern.
     
  16. Emmettology 101

    Emmettology 101 3/4 ton status

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    Another thing to add to Blazer1970's post is that the LT-1 Aluminum heads from the 93+ will bolt just bolt up to the regular 305 blocks without a lot of work! Holes need to be fill and machined and other holes need to be drilled. THe is supposedly a guy in York, PA that can modify the Lt1 aluminum heads to work on regular 350 blocks.
     
  17. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    Well I dont know how we got on the subject of vortec/lt1 heads but while we are there... what is the difference between lt1 is aluminum and vortec are iron.

    I just ordered my new flywheel which is where this topic started from. Anyhow I just ordered a 1991 chevy pickup flywheel for a 350 manual. It will be in tomorrow and was $117. I could have paid $75/100 used and had it cut for $45 but hell that is almost a new ones price.

    ok... now as for the bolt holes in the center of the intake being different I was told that is just because of a TBI intake and has nothing to do with vortec heads.
    I have pics of a 1987 camaro intake for a carb and the holes line up. My head id numbers tell me that they are just cast heads with 1.94 Intake and 1.50 Exhaust. My motor being a 1991 I was told was a vortec block with cast heads.

    to that note I have a few pics for yall... 2 show the intake holes and 1 shows the hydrollic roller hold down plate ( or whatever you call it /forums/images/icons/smile.gif )

    you can see the pics here...
    if it asks you for name and password it is Administrator with no password... still dunno why it is doing that.. /forums/images/icons/grin.gif
    http://68.45.68.102/PROJECT_NJLEGAL/htm/2002_b.htm
     
  18. Yuba K5

    Yuba K5 Registered Member

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    i did the same thing that you are trying to do,except the exact oppisate.i put an sm465 in a 90 blazer and i did have to pay $120 for a new flywheel.and the bolt holes for a carberated chevy intake line up to a 90 91 motor.but the center two bolts are at a different angle. i have seen guys notch these an grind a spot for the bolt to sit flat and never have any problems.gm performance catalog sells an intake made for this
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    The difference is that Vortec and LT1 heads have no crossover, and thus, have no center bolts for the intake at all. (8 vs 12 intake bolts)

    Up to '86 (think thats right) the intake bolts were ALL angled. Then '86 to whenever they got rid of crossovers ('96 was when vortecs came out) they used 12 bolts still, but with the center 4 now being vertical. From then on out, there are 8 intake bolts, and all are vertical, and none in the center.


    "Center" intake bolt holes (whether they are canted, straight, or non existent) have nothing to do with whether it was TBI, carb, or TPI, they were simply eliminated because they were no longer needed without the exhaust crossover.

    Vortec block is a complete misnomer, its simply a standard 350 block. It was/is ALL in the heads/intake. Unlike LT1's, 5.3's, etc., of course, where bore, stroke, and design all changed, thus making the block different, and therefore unique.

    Your pictures clearly illustrate that the motor isn't a Vortec or LT1 motor : )
     
  20. wrathORC

    wrathORC 1/2 ton status

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    It's just a regular motor. The police required more horses so GM threw in an agressive hydraulic roller cam.
     

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