<VV> re: yoke bolts

[Sethracer at aol.com]

In a message dated 1/24/2007 9:13:11 AM Pacific Standard Time,  
s10birdman1966 at yahoo.com writes:

Barry,the 'correct' bolts have a taller head to get a wrench on,no  
problem...the un-threaded portion is also necked down from .310" dia near the  head,to 
.285" for clearance in the yoke before the threads start : a 'common'  bolt 
may bind up,causing the strap to be loose or (you) to break the bolt off  in the 
yoke...bolts from any RWD GM are useable,if you don't have the Corvair  
ones,but are 5/64ths longer,not an issue if you chase out the threads in the  yoke 
first ; these don't use lock washers,btw...Tom  Z..//




Yes to what Tom said! - In addition the 5/16 thread bolts can have the  heads 
cross-drilled for Safety wire. It is a bit of work but will eliminate, or,  
at least, minimize the chance of them coming loose. Another thing to watch out  
for on the 65 is to make sure that nobody has somehow swapped a bolt or two 
from  the valve cover holddowns to the U-joint straps. The bolts are both 
1/4-20 and  almost the same size. The U-joint strap screw is a Grade 8, the valve 
cover  holddown a Grade nothing (Probably a grade 2, but unmarked). Neither one 
 can perform the others job. The Grade nothing may fail if used on the 
U-joint,  the Grade 8 may back out due to lack of "preload" on the threads if not  
torqued to grade 8 specs - which you better not do into the Corvair Aluminum  
threads on the cylinder head. I think that this "unwanted interchange" was the  
actual reason Chevy changed to the larger bolts for 1966 and up.  - Seth  
Emerson