Does anybody make 4 bolt main caps?
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Does anybody make 4 bolt main caps?
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
Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?Quote:
Originally Posted by tufcj
Yup, sure do... Standard practice. :t:Quote:
Originally Posted by tufcj
Yep but those blocks are very hard to come by, I think they were cast for Trans Am racing.Quote:
Originally Posted by fifesjeep
Cool, makes sense. I'd be nice to stumble upon one in good shape. :wink:Quote:
Originally Posted by Blown7
The one at 74 Javelin was good enough. I still wonder why they did not make more in any of those ever.
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
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.