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quick Compatability ? --- Heads and Block---need quick info

Discussion in 'The Garage' started by jakeslim, Jul 17, 2004.

  1. jakeslim

    jakeslim 1/2 ton status

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    Ok, will these heads off my old engine (3973487....71-72...350..........used on 71-72 350 LT1, 75cc chamber)

    work with this block off a newer truck (10054727...350...86-up...2 or 4...one piece rear seal)

    Also, how do I tell if its a 4 bolt main or 2 bolt main? I am diving head on into block and head swapping /forums/images/graemlins/histerical.gif /forums/images/graemlins/waytogo.gif
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Yes the heads will work, but I don't know why you'd waste the time swapping them. If you use centerbolt valve covers now, you'll need a new intake manifold or to drill yours to fit, and I doubt you will gain much of anything by swapping heads.

    You can find out if your engine is two or four bolt main by removing the oil pan but if it's in a truck I don't know why it would matter anyway.
     
  3. jakeslim

    jakeslim 1/2 ton status

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    thanks for the reply Tim. Well let me explain a bit more. The block that the heads are on is bad. One of the cylinders is scratched. So what I did was pick up the newer block from pick n pull. It is actually a newly rebuilt block whos car met its demise. The heads on the older block are good, the newer block is good. I have the intake from the newer block(stock aluminum) so I should be good.

    So its not a performance gain I'm looking for, just putting together an engine that runs good.

    Thats what I thought about the 2 or 4 bolt main. I dropped the pan and its a 2 bolt.

    Thanks for the info.

    /forums/images/graemlins/waytogo.gif
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    New style (centerbolt head) intake will not fit on old heads without drilling it.
     
  5. Big Red

    Big Red 1/2 ton status

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    <font color="red"> how badly scratched was the block? cus u could do a .030 overbore and probably get that scratch out...not sure if you'd want to buy a new set of pistons. if u do, u can go to northernautoparts.com and pick up a set of decent ones for fairly reasonable price. </font>
     
  6. ben427

    ben427 1/2 ton status

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    Yeah your 86 up intake will not work with the older heads. Different angle in the centre 4 holes.
     
  7. jakeslim

    jakeslim 1/2 ton status

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    i have the old intake also. I will pick up an edelbrock performer at local parts store.

    The block can most likely be bored out. It will become my "garage" project engine. I plan on having it bored, but that will be sometime since $$ is not growing on the tree even though i water it.
     
  8. Bruiser

    Bruiser 1/2 ton status

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    Guys are reading it wrong, he is wanting to put his old heads and intake on a newer style block. Yes it will fit and you will not have to buy any other intake. The main thing they changed on the 86 and newer blocks is it has one piece rear main seal (instead of older 2 piece) and it may have the bosses to machine for a roller came.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Any chance you can give me the suffix code off of that 2 bolt block? /forums/images/graemlins/smile.gif

    (typically 2 or 3 letters in amongst the digits stamped on the deck surface of the block, what would be behind the alternator in a truck.)
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Guys are reading it wrong, he is wanting to put his old heads and intake on a newer style block. Yes it will fit and you will not have to buy any other intake. The main thing they changed on the 86 and newer blocks is it has one piece rear main seal (instead of older 2 piece) and it may have the bosses to machine for a roller came.

    [/ QUOTE ]

    Actually no, you're reading it wrong. Initially he wanted to use his stock, newer aluminium intake on his old style cylinder heads which will not work.

    And actually don't generalize about 86-up motors. My engine is 1986, so it has the OLD heads and the NEW block from the factory. So, it uses the old valve covers, but has the new, 1 piece rear main seal.

    87 and up engines will use the centerbolt heads, and thus the new intake bolt pattern (actually the bolts are in the same place, just the center four are at a different angle).
     
  11. Bruiser

    Bruiser 1/2 ton status

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    "Ok, will these heads off my old engine (3973487....71-72...350..........used on 71-72 350 LT1, 75cc chamber)

    work with this block off a newer truck (10054727...350...86-up...2 or 4...one piece rear seal)
    "

    Origonal post not until someone mention using centerbolt valve covers did he bring up the intake this post here

    "Yes the heads will work, but I don't know why you'd waste the time swapping them. If you use centerbolt valve covers now, you'll need a new intake manifold or to drill yours to fit, and I doubt you will gain much of anything by swapping heads."

    Which was not a concern since he is not wanting to put center bolt valve cover heads on it

    Simple fact is for his question (which was confused with many things that didn't pertain to it)
    Is yes his old heads will fit, along with his old valve covers and intake

    Gen. I blocks (1955-1991) have many of there parts are interchangable. I made the assumption that he did not want all the particulars of what was different and what was not. What year heads got centerbolt valve covers have nothing to do with what he is asking "will these heads off my old engine,work with this block off a newer truck" . As to differnce of blocks, again this doesn't really matter to his question so was generlized. Dipstick locations varied, 86 and later had once piece seals which made them externally balanced (making crankshafts,oil pans,flywheels,flexplates and sealing surfaces not interchangble) again does not matter for his question. Also 87 and later had taller lifter bores ,and bolt bosses in the lifter valley to facilitate the use of a factory hydrolic roller cam. (again of no use to his question but added because he could have one of these and makes it slightly more valuable to someone who wants to build a roller motor.

    more information need? Some early one piece blocks had the mechanical fuel pump boss cast into the block but holes were not drilled (again irrelevant but was said can't generlize)

    Also some blocks (some may have casting "638" were drilled for both 2 or 4 bolt mains.

    Did I miss anything? I am sure someone will let me know if I did, I generalized since it wasn't what he asked. I do have the information available and will be happy to compare difference to Gen.I to Gen.II if you would like?
     
  12. 84gmcjimmy

    84gmcjimmy 1 ton status

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    how do you know all this /forums/images/graemlins/eek.gif /forums/images/graemlins/bow.gif
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    how do you know all this /forums/images/graemlins/eek.gif /forums/images/graemlins/bow.gif

    [/ QUOTE ]

    You pick up on stuff when you're scrounging around for parts and you can't find what you're looking for, it's just kinda the way it works.
     
  14. 84gmcjimmy

    84gmcjimmy 1 ton status

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    Okay, I'll learn some when I take everything off my frame then /forums/images/graemlins/cool.gif
     
  15. Bruiser

    Bruiser 1/2 ton status

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    I like to read any books pertaining to Chevy's

    "Chevrolet Small Block Parts Interchange Manual" SA Design ISBN 1-884089-25-9

    I have quite a few books, Big block interchange,Rochester book,Multiple TPI books,4wheelers Bible,Chevy &amp; GMC Light Truck Owners Handbook.

    Knowledge is Power /forums/images/graemlins/waytogo.gif
     
  16. 84gmcjimmy

    84gmcjimmy 1 ton status

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    Woah! I like to read, but I have books on rebuilding engines, and fabricating... still need more /forums/images/graemlins/woot.gif
     
  17. jakeslim

    jakeslim 1/2 ton status

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    hmmm...ok. Well I have both blocks on my garage floor. BUT something you said makes me wonder if the "newer"block can even be used? The truck its going into is manual. The newer block is from an automatic so the flywheel is different. Can I switch them, along with clutch etc?

    /forums/images/graemlins/thinking.gif /forums/images/graemlins/whistling.gif
     
  18. Bruiser

    Bruiser 1/2 ton status

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    You will need a 86 or newer flywheel. They can be either 12 3/4" or 14". You will need to find one that same size as your old one to be able to reuse your clutch and pressure plate. Don't forget you will need a new pilot bushing(it's cheap and should never reuse old ones assuming you are going to junkyard to get the correct flywheel) Some flywheels are drilled for both clutch sizes so if you come across one of these (especially if you have the smaller clutch size I would use this since later when you need to replace your clutch you can go bigger (isn't bigger always better on a K5 /forums/images/graemlins/rotfl.gif ) I have some part numbers if you need just pm me if you do. I will be gone for a bit since have to go do some work, chaning out a starter for a Frequ. Drive at the mill and can only do it on weekends so have to work /forums/images/graemlins/frown.gif
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    You'll need to buy a new flywheel for the 1 piece rear main seal. Your clutch will bolt up, but you'll need a new flywheel.
     

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