Results 1 to 9 of 9

Thread: 4 Bolt Caps

  1. #1
    Thank you from BT Master (OIIIO)
    Join Date
    Oct 2006
    Location
    Virginia
    Posts
    771

    4 Bolt Caps

    Does anybody make 4 bolt main caps?

  2. #2
    Thank you from BT ULTIMUS MAXIMUS STATUS tufcj's Avatar
    Join Date
    Apr 2004
    Location
    Watkins, CO
    Posts
    2,864
    Pro-Gram Engineering. http://www.pro-gram.com/

    I believe it's a 401 mod, as the main webs are thinner on the 304/360 blocks and don't have enough meat to drill bolt holes.

    Remember that the block will also have to be line bored after installing the caps.

    Bob
    tufcj
    1969 AMX
    1967 Rambler Rogue

    If you need a tool and don't buy it...
    you'll eventually pay for it...
    and not have it.
    Henry Ford

  3. #3
    Thank you from BT Master (OIIIO)
    Join Date
    Oct 2006
    Location
    Virginia
    Posts
    771
    Quote Originally Posted by tufcj
    Pro-Gram Engineering. http://www.pro-gram.com/

    I believe it's a 401 mod, as the main webs are thinner on the 304/360 blocks and don't have enough meat to drill bolt holes.
    Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?

    Quote Originally Posted by tufcj
    Remember that the block will also have to be line bored after installing the caps.

    Bob
    tufcj
    Yup, sure do... Standard practice.

  4. #4
    Thank you from BT Jedi gear head
    Join Date
    Jun 2005
    Location
    CT
    Posts
    608
    Quote Originally Posted by fifesjeep

    Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?
    Yep but those blocks are very hard to come by, I think they were cast for Trans Am racing.
    1979 Jeep CJ-7 401 AMC, GMC 6-71 Blower 10% overdrive, Bugcatcher with electronic fuel injection and a little N2O for fun, all self built. (this supercharger stuff is easy)

  5. #5
    Thank you from BT Master (OIIIO)
    Join Date
    Oct 2006
    Location
    Virginia
    Posts
    771
    Quote Originally Posted by Blown7
    Quote Originally Posted by fifesjeep

    Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?
    Yep but those blocks are very hard to come by, I think they were cast for Trans Am racing.
    Cool, makes sense. I'd be nice to stumble upon one in good shape.

  6. #6
    Helpfull BT forum member Swabie
    Join Date
    Sep 2006
    Posts
    35

    360 block

    Quote Originally Posted by fifesjeep View Post
    Cool, makes sense. I'd be nice to stumble upon one in good shape.
    Yes they were used in Trans Am but some of the later service replacement 360's came with the thicker webbing. I remember seeing one in a 74 Javelin that had a factory motor repalced in the mid 80's and it had the thick webs. Only one I ever saw

  7. #7
    Bulltear forum member New to the forum
    Join Date
    Jan 2013
    Location
    Argentina
    Posts
    1
    The one at 74 Javelin was good enough. I still wonder why they did not make more in any of those ever.
    Everyone, take one... repo trucks for sale

  8. #8
    Thank you from BT Tech Master Bulltear Forum
    Join Date
    Nov 2005
    Location
    Middle of the Iron Range MN
    Posts
    1,229
    The factory service blocks were basically a blank with slightly heavier castings, it was up to the final user what they were at the machine shop (304/360) IIRC

  9. #9
    Bulltear forum member New to the forum
    Join Date
    Sep 2014
    Location
    Ecuador
    Posts
    4
    My first post here. AMC 1970 390 and all 401's will accommodate 4-bolt mains. The "service block" is as described above. It has the same bottom end as the late 390 and all year 401 and was a 4.08" bore 360 cylinders with enough material in the cylinder bores for the service department to bore to 4.165" 390 / 401 specs if required. There were some smaller 290 engine blocks made with 4-bolt provisions but that was a Trans-Am race block and very rare indeed.
    Milidon and Pro-Gram Engineering make excellent 4-bolt main caps. Milidon availability can be iffy, Pro-Gram will get them to you in a reasonable amount of time. You can buy the three middle caps with 4-bolt. Pro-Gram also offers billet #1 & #5 caps but those are 2-bolt. Just keeps the billet theme going. I have all 5 on my '70 390 race engine. You will need to line bore / hone ANY block if you change the caps (even if factory standard caps). Caps are married to the bore.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Bulltear Ad