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Stupid Newbie Question

Discussion in 'The Garage' started by johnnyclueless, Feb 17, 2005.

  1. johnnyclueless

    johnnyclueless Registered Member

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    I have a 78 and I just cannot tell if the previous owner had taken out the 350 and replaced it with 305. I've tried to get the number off the block behind the alternator - just can't read it. What would be the easiest way visually to tell whether it's a 305 or 350? Thanks guys
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    You can't , same extrenal dimensions , unfortunately you can't just look at a small block and tell , and many times the original engine has been replaced . You need to spray the block clean and try to read it . I would say check the heads , but sometimes people like to put 305 heads on 350's so that may not be accurate if they swapped :k5: :k5:
     
  3. JK5

    JK5 1/2 ton status GMOTM Winner

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    Sand the block with some sandpaper....
    Once you do that...they'll be readable.
     
  4. Z3PR

    Z3PR Banned

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    I've heard that there is a way too tell by the harmonic ballancer, but just can't remember. Something like the 305 has a wider or narrower ballancer then the 350's, or so I've heard anyways. I could be wrong, anybody know anything about that ???
     
  5. readymix

    readymix 3/4 ton status

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    the balancer on a 305 is wider than the 350.
     
  6. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    It still could be swapped out . Most replacement motors come witout anything except tin sometimes :k5: :k5:
     
  7. diesel4me

    diesel4me 1 ton status Premium Member

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    oh yes you can...

    There is a casting number on the drivers side rear of the block,right where the tranny bolts up--its got BIG numbers,about 6 of them,but its a bitch to read while its in the truck,but with a mirror and a light you should be able to read it(after scraping a ton of muck off of it!)--then go to www.mortec.com and look up the number--it wont tell you much more than the cubic inch size,if you need to know the year and model it came in,you'll have to clean the numbers off better under the altenator-rub some paint on them and wipe off with a rag,it will help them show up better --my 86 305 also had "5.0" casted into the block right next to the big numbers on the block next to the tranny bellhousing..:crazy:
     

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