71 XLT 390

Post by **DuckRyder** » Thu Mar 29, 2007 5:51 pm

It is felt that it adds strength and rigidity to the bottom end.

XLT · Post by **XLT** » Thu Mar 29, 2007 6:36 pm

kid wrote:Borderline 500 plus cube stroker sitting there.

kid · Post by **kid** » Thu Mar 29, 2007 8:12 pm

It made the thin spots in the original casting stronger. There was a 427 race motor that turned 9000 rpm for over 8 hours without breaking the bottom end. Most FEs broke parts at sustained 8000 rpm. The Block girdle with its webbing ties the bottom of the bores, the cam journals and the main bearings together.

My 428 race motor came apart at 7000 right on the #3 main cap webbing. 10th race that night. Total destruction of everything below the deck surfaces. Crank 2 mangled rods and 6 bent rods, lifters (all of them) crushed when the block flexed in their bores, cam broke in three places, timing chain snapped and many bent push rods and every piston damaged or destroyed. All because of sustained block flex that that extra webbing would have controlled. The block cracked right where the middle line comes across.

rjewkes · Post by **rjewkes** » Thu Mar 29, 2007 11:07 pm

why does an fe only have 3 freeze plugs on each side of the block and 302/351's/400's have 4 on each side?

kid · Post by **kid** » Thu Mar 29, 2007 11:31 pm

One between each bore for casting clean out and one at front and back for the same reason.One at each cylinder center line. Block internals were tighter and casting became more precise making the sand harder to clean out.

kid · Post by **kid** » Thu Mar 29, 2007 11:32 pm

FEs were not my first engine they are my most loved engine. Heavy beasts but tough as hell.

XLT · Post by **XLT** » Sat Mar 31, 2007 1:39 pm

68F250 wrote:Yeah it's got the crossbolt nubs.

There are little nibs that point straight at the bolt head area of the main caps.

kid · Post by **kid** » Sat Mar 31, 2007 1:42 pm

That is the cross bolt main nibs, Yes.

XLT · Post by **XLT** » Sat Mar 31, 2007 1:48 pm

kid wrote:That is the cross bolt main nibs, Yes.

I don't follow...

kid · Post by **kid** » Sat Mar 31, 2007 1:52 pm

The nibs are the unfinished bosses for the cross bolt main caps, The block does not have the holes drill the bosses are not finished and the main caps are not set up for cross bolt mains.

XLT · Post by **XLT** » Sat Mar 31, 2007 1:55 pm

unfinished bosses? What do you mean?

kid · Post by **kid** » Sat Mar 31, 2007 2:30 pm

Okay in my early picture the upper two red circles show the nibs (nib is my grandfathers term for unfinished casting of mounting bosses.) They are the piece almost flush with the bottom of the block that point right at the main caps.

When that nib is machined into a boss then center drilled you have the start of cross bolt mains. The first 4 bolt main system in any car. Then you need cross bolt main caps that have a little boss with threaded hole that points at the hole in the block. A bolt and spacer makes up the rest of the setup.

XLT · Post by **XLT** » Sat Mar 31, 2007 4:17 pm

Bosses (extra pads) are cast (nibs?). These are drilled and tapped to accept a threaded stud.

Closest I could find for bosses. Is it correct?

kid · Post by **kid** » Sat Mar 31, 2007 6:29 pm

Yours are drilled and tapped? On Cross bolt mains the hole goes all the way outside and the main cap has 2 threaded holes. Plus the view I see in the pics they are not machined smooth so someone took a block and modified it by tapping into those nibs. Nibs is probably a way of not offending my Grand mother by saying nipples.

If you compare the fifth pic downs view with your first picture you will see quite a difference http://www.428cobrajet.com/id-block.html in the nibs

68F250 · Post by **68F250** » Sat Mar 31, 2007 6:45 pm

Nibs, nubs, whatever.

Here's what would have to be done.

http://www.customdesignperformance.com/ ... sbolt.html

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