[DeTomaso] Head Bolts or Studs?

[JDeRyke at aol.com]

In a message dated 12/21/07 4:41:57 PM, artstephens at charter.net writes:

>      I have to decide whether I want studs or head bolts to hold my new CHI 
> aluminum heads to my Cleveland block.  My concern with studs was that I 
> thought it made it impossible to get the head off in the car,  is that right?  
> 
Wrong. I've had studs on my Cleveland-in-a-Pantera for 18   yrs and aluminum 
heads are so light they come off fine by one person. Iron heads with bolts are 
so heavy its almost mandatory there be two or three people to pull them. You 
will need composite head gaskets- steel shim gaskets will permanently dent the 
soft aluminum. And teflon-coated compositie Fel-Pro gaskets allow the 
aluminum to shift slightly with temperature without damage, and no prying to break 
them loose when removing.

>  Someone told me that it would be better to use the studs since I have 
> aluminum heads on a cast iron block and because of the different expansion rates 
> of the two metals,  the stud would give more to allow the aluminum to 
> expand? 
> 
Studs hold better for a given torque value because 100% of the twisting force 
used to tighten goes to holding down the head rather than some torque being 
expended to twist the bolt during tightening. There is NO 'give' with either 
system; if there were, kiss your head gaskets good-bye! Aluminum heads on an 
iron block take a different torque spec than iron-on-iron. And aluminum heads on 
an aluminum block take a third torque spec. Finally, valve adjustments have 
different specs with solid cams & alloy heads. Check with your head mfgr- not 
all aluminum heads have the same deck thicknesses, the same torque specs or the 
same valve clearances.

>  I'm planning to use ARP fasteners.  One potential advantage to the bolts,  
> is that the small headed bolts should allow retorquing without removing the 
> valve train. 
> 
Maybe- 12-point nuts or jet-nuts on studs are smaller yet. And if you use 
some brands of stud girdles (highly recommended), it makes no difference at all- 
you will have to take stuff off for fastener access with either bolts or 
studs. In any case, re-torquing heads is a one-time thing, to be done after the 
initial firing-up and not touched again until the next tear-down so its a minor 
consideration. Constant head-re-torquing is a myth and can damage an engine. 
Mine have been re-torqued once in 18 yrs. ARP fasteners are good products; 
install studs in the block per their specs, not per internet info. 
Better luck in '08, Art- J DeRyke
> 


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