Ball Stud Hemi and the 400 B-Block

[Xcudame]

Hey, I was just thinking about the Hemi Ball-Stud engine that Chrysler was considering to replace all big blocks with. As we know there were only a handful of the 444 cubic inch version built and tested. With two surviving, one that Tom Hoover had and one the I think the Chrysler museum has.

Anyway, I remember reading they intended to make two version, a 400 low deck and a 444 high deck that would use a lot of the same components except for the crankshaft and connecting rods. Pistons and rings were to be the same to reduce production cost.

Long story short, my brain got to thinking about the 400 blocks that were casted in 1971 for the 72 model year. These early blocks and even the later blocks had really beefing main webs. You see that in all the engine build up sites and books. Since this has always been a weak stop of the Mopar Big block, even our beloved cross bolt 426, I'm wondering if the engineers preparing the 400 blocks beefed up this area for preparing for the ball-stud hemies? Then when the ball-stud hemi got abandoned they just kept that area of the block beefier on the 400. It kinda makes sense.

What say you my Mopar buddies. Am I off the wall? Or did we almost have 400 ball-stud hemies and the web area confirms this?

 

[Racer Dave]

It's hard to say what the Chrysler engineers had in mind, but from my perspective the ball-stud arrangement would have only been for cost-cutting, not performance. The best (only?) reason to use a ball-stud setup is so you can have canted valves like a BBC with wedge chambers. The Hemi doesn't really benefit from that since it is a cross flow engine, i.e. the intake port, cylinder center, and exhaust port are all inline. Wedge heads only wish they could have as good of valve angles as the Hemi!

Ball-stud is an inferior technology compared to rocker shafts. Just look at all the gyrations the Chevy guys have to go through with a big block: screw in studs, pushrod guide plates, and stud girdles in an effort to achieve rigidity already present in the Mopar shaft system. Max-effort BBCs almost universally end up with a shaft system, albeit with individual shafts and stands per valve.

It's an interesting thing to ponder though....had they built a low block ball stud Hemi that was lighter and less expensive it could have become the defacto big block - much like the 5.7 Hemi - and there might have been more of them sold. With the huge 4.34" bore of the 400 they probably would have flattened the chamber somewhat to more resemble the Gen 3 Hemi head so you could get some compression ratio without a huge dome on the piston. Or maybe the engineers had a crystal ball and knew we were going stroke those low blocks - first as 451s, and then WAY bigger

 

[Xcudame]

Thanks for replying Racer Dave and supplying your thoughts. And a 400/451 engine is a nice combination that Chrysler should have built!

I've always loved the Mopar rocker shafts myself. Always pretty stout even with just the stamped steel rockers.