fifesjeep
Does anybody make 4 bolt main caps?
tufcj
Pro-Gram Engineering. [url]http://www.pro-gram.com/[/url]
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
fifesjeep
[quote=tufcj]Pro-Gram Engineering. [url]http://www.pro-gram.com/[/url]
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.[/quote]
Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?
[quote=tufcj]Remember that the block will also have to be line bored after installing the caps.
Bob
tufcj[/quote]
Yup, sure do... Standard practice. :t:
Blown7
[quote=fifesjeep]
Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?
[/quote]
Yep but those blocks are very hard to come by, I think they were cast for Trans Am racing.
fifesjeep
[quote=Blown7][quote=fifesjeep]
Hmmm, I thought that there were thicker casted 360 blocks that would support this mod?
[/quote]
Yep but those blocks are very hard to come by, I think they were cast for Trans Am racing.[/quote]
Cool, makes sense. I'd be nice to stumble upon one in good shape. :wink:
JERSEJO
[QUOTE=fifesjeep;127920]Cool, makes sense. I'd be nice to stumble upon one in good shape. :wink:[/QUOTE]
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
PagetHamington
The one at 74 Javelin was good enough. I still wonder why they did not make more in any of those ever.
ironman_gq
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
SuperStockAMX
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.
