Re: Adding extra 3/8 head bolts/studs on a 401 block INFO needed

["Bob" <masheen@xxxxxxx>]

Joe this is a very good question!  Who's got some answers?  I'd be 
interested in knowing how the torque sequence is changed when these four 
3/8" bolts are utilized and how many lbs-ft of torque is used on them for 
the final pass.  And yet another thought:  Should you go with a 16 or 24 
thread?  Not sure which is stronger, but since the other head bolts are a 
course thread, maybe 3/8-16 is the better way to go.  I'd also like to know 
what the bolt spacing is and if the specs we are talking about are 
applicable to all the V8's.
Page 33 of the AMC Power Book states - "machine the block and heads to 
accept eight special bushings and studs (four per side) to compensate for 
the spacing problem.  The procedure involves the drilling of the block for 
the new studs which are 3/8-inch in diameter.  The second step is to machine 
the heads to accept the special bushings that the studs go though to hold 
the head down securely."
This is all the info given about this modification.  The photo at the bottom 
of the page clearly shows bolts, not studs being used.  The reference to the 
"special bushings" has also left me pondering why they are even needed.

My personal preference is to go with studs if clearances allow.  You can 
find grade 5 studs, nuts, and/or bolts at any bolt distributor or most 
likely ARP.  If using bolts/nuts, use washers under them along with assembly 
lube in that area and the bolt thread to prevent chewing up your precious 
heads.  Be sure that the geometry under the bolt head is suited to that of 
your washer.  If the bolts' washer face is larger than the ID of the washer, 
you will not get the full area of the bolt head to spread its clamping force 
across the washer.  Baaaaad jue jue!!  You may already know this, but I'm 
just making sure you've got the bases covered.  Please post or email me 
anything you happen to find out.  Thanks much!!

Bob Rapp
NN, VA
70 Machine