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SBC year differences

Discussion in 'The Garage' started by GMCJason, Jul 13, 2005.

  1. GMCJason

    GMCJason 1/2 ton status

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    I have access to a 350 block that I'm considering building for use in my '90 Jimmy. The casting number on the "new" block is 3970014 which seems to indicate it's from the early 70's.

    Are there any reasons why this block wouldn't work in a 1990 TBI truck? I'm concerned about the sensors and such. I'd like to build the engine and just swap 'em when I'm done so I don't have too much down time on my truck.

    If this won't work what years should I be looking for? Anything too old? Too new?

    Thanks.

    Jason
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Everything should bolt right in less the TBI intake, you'll need to do some grinder work on the 4 center mounting bolts. You will need to remove a plug from an oil passage above the oil filter, and you'll need to remove a coolant plug to install the knock sensor as well :)
     
  3. sled_dog

    sled_dog 1 ton status

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    IF he reuses the 90 heads there will be no intake modification needed(yes I know he said less to swap the better). If you use the older heads, they have angled center holes and need to be ground out like noted.
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Most of the bigger machine shops would already have a set of those heads , would cost more upfront , but the engine could be built , and then after removal of the old one he could get his core charge back by dropping off his heads .
     
  5. GMCJason

    GMCJason 1/2 ton status

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    Thanks guys. I'm still planning but the thought is to build a 383 with Vortec heads. I know I'll need the GMPP intake but that should fix any fitment problems, right? I wasn't thinking about the heads but more the bottom end.
     
  6. Blazer1970

    Blazer1970 1/2 ton status

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    3970014 will be a two piece rear main seal block which means that your flywheel / flexplate from the '90 motor will not bolt to the old motor's crankshaft. If you have or find the correct flexplate, it will work.
     
  7. ProJunkRacing

    ProJunkRacing 1/2 ton status

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    anybody got a pic of modifing the heads i need to do that or a write up about doing it
     

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