1970's Block & Gen5 Heads???
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1970's Block & Gen5 Heads???

  1. #1
    Senior Member Constant840's Avatar
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    Default 1970's Block & Gen5 Heads???

    I maybe able to pick up some nice basically stock Gen 5 heads for a good price. I am told that these heads will not bolt up to my '70's era block due to gasket issues.

    Intesrested in everyone's take on this.
    Thanks.

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  3. #2
    Senior Member Constant840's Avatar
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    Whoa. Don't everyone answer all at once.
    So I guess I am the first person to ever encounter this?
    Call me a pioneer. ha.

  4. #3
    Senior Member Futs's Avatar
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    Won't work.

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    Senior Member Constant840's Avatar
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    ^^^ Thanks there chief. A real wealth of knowledge.

    I am getting conflicting opinions on this. I have some people telling me it can be done and others telling me it can't.
    Some say a Gen5 block will accept older heads and others say it is the other way around.
    Below is a response I got when I asked this question somewhere else...


    "i have done it the f1047 up to 4.540 bore or f1037 for smaller bore the mark 4 block was started in 1965 as the 396 and was end around the late 80s this block has a closed down deck less holes in the deck making for a stronger and better block i think. the 5/6 blocks have a open up deck bigger holes for coolant and re work flow on the deck 5/6 heads can fit on older blocks but not that great of a head less you have put the 7/16 studs on them so you can run the old type ajustable rocker arms you can not run the old mark 4 heads on the gm 5/6 mark blocks there not much around the deck on the older head to hold the head gasket seal were it gets thin is the lifter valley side of the deck"
    "they are felpro numbers the f1037 is a mark v454 gasket . the f1047 is big bore v 502 . alot of the felpro are print out for both water ports older mark 4 and 5/6 the 1037 is the one i have used on the older block with 5/6 heads if mark 5 /6 heads i drill and tap them out for the older 7/16 top and bottom rocker stud ARP makes a stud that works in the mark 5/6 head thats 7/16 and 3/8 bottom but alot of builds i do i used the 7/16 top and bottom stud keeps them from busting off"



    Is this guy nuts?

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    Village Idiot fc-Pilot's Avatar
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    I did not want to say anything since I have not had a bunch of experience between the two but here it goes. I have heard of a few (and only a few) that had success mating the two. The water ports are the problem being that everything else is the same (head bolt pattern, valve train layout, and bore spacing). I have heard guys "carefully" check to make sure the deck of the block and deck of the heads will match up well enough to seal the water passages. I don't know which part numbers they used and had success with but I have personally seen some that will NOT match up (being that I saw how much water leaked into the block.)

    Paul

  8. #6
    Senior Member Constant840's Avatar
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    Thanks Paul.
    These are the responses and experiences I am looking for. Quite a few views for only a couple responses. I know I am an a-hole but this is ridiculous!
    Last edited by Constant840; 07-24-2008 at 10:49 AM.

  9. #7
    Some guy obnoxious001's Avatar
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    Quote Originally Posted by Constant840 View Post
    ^^^ Thanks there chief. A real wealth of knowledge.

    I am getting conflicting opinions on this. I have some people telling me it can be done and others telling me it can't.
    Some say a Gen5 block will accept older heads and others say it is the other way around.
    Below is a response I got when I asked this question somewhere else...


    "i have done it the f1047 up to 4.540 bore or f1037 for smaller bore the mark 4 block was started in 1965 as the 396 and was end around the late 80s this block has a closed down deck less holes in the deck making for a stronger and better block i think. the 5/6 blocks have a open up deck bigger holes for coolant and re work flow on the deck 5/6 heads can fit on older blocks but not that great of a head less you have put the 7/16 studs on them so you can run the old type ajustable rocker arms you can not run the old mark 4 heads on the gm 5/6 mark blocks there not much around the deck on the older head to hold the head gasket seal were it gets thin is the lifter valley side of the deck"
    "they are felpro numbers the f1037 is a mark v454 gasket . the f1047 is big bore v 502 . alot of the felpro are print out for both water ports older mark 4 and 5/6 the 1037 is the one i have used on the older block with 5/6 heads if mark 5 /6 heads i drill and tap them out for the older 7/16 top and bottom rocker stud ARP makes a stud that works in the mark 5/6 head thats 7/16 and 3/8 bottom but alot of builds i do i used the 7/16 top and bottom stud keeps them from busting off"



    Is this guy nuts?
    I think he may have it backwards a bit. The older heads and aftermarket heads definately work on the newer blocks with the proper head gasket. As I told you, I was pretty sure it wasn't a workable situation for you, but figured you would get some interesting responses on here.

  10. #8
    Big Boys Toys Murray PE 857's Avatar
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    Years ago I needed to put Dart Mark IV heads on a Gen 5 block. I ordered the head gaskets and a small water block off plate from Scoggin-Dickey Chevrolet in Texas. They had just the right combo for that application.

  11. #9
    Senior Member MACHINEHEAD1's Avatar
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    I think the fel pro site has all the info you need. If you have a 1017 head gasket around it will tell you what to look for in the little instruction packet.

  12. #10
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    Years ago, Apple Chevrolet in York, Pa had a special gasket that would mate the gen5 to Mark4.

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