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Re: head studs

To: Lizirbydavis@cs.com
Subject: Re: head studs
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 28 Feb 2005 11:26:48 -0500 (EST)
On Sun, 27 Feb 2005 Lizirbydavis@cs.com wrote:

> Is it prudent to replace the head studs when rebuilding?  

It's not usually needed unless the studs have been over torqued.

To test that the studs are okay, thread a nut all the way down the threads
on both ends. If you get _NO_ resistance, then the threaded portion is
okay. The next step is to check the length of the studs. If there are any
studs that are longer - they have stretched and are therefore headed to
the ash bin. Bolts will stetch before they break. If they've stretched,
the next step is that they will break.

> Is there a way to 
> tell if the present hardware is deficient?  

Se above.

> Is it worthwhile to buy the 
> "upgraded" studs?  APT sells the set for $129.00, Moss is $159.00. 

Read the fine print on those upgraded studs... they are for heads that
have been milled to be very thin (e.g. for really high compression).

If you're running under 10:1, you probably can't use those studs (note
that they are ARP studs) because they are too short.

> I did buy new 
> fasteners for the mains and con-rods.  The bolts from Moss have a flange 
>(like a 
> washer).  The old hardware does not. Why are there no lock washers on main 
>cap 
> and rod bolts?  Should I use locktite?  

The mains use bolts. No lockwashers!! The factory spec's lock washers on
the early motors, but dropped that spec eventually. This was accompanied
by a factory tech bulletin indicating that the later-style bolts should be
used in place of the early bolts. Note - the early bolts are longer by
about 1/8". So, use the late-style bolts with no lock washers for the main
caps. You do not need loctite. Yo DO need to toque everything properly.

The conrod bolts have a little pad on the shoulder to distribute the
clamping load over a bigger are on the rod cap. Again, no loctite and no
lock washers.

Obligatory warning - the early main cap studs will bottom out in the
casting if you install without the lockwashers. If you discover that you
have the early studs, try to find a set of late-style studs and use those
instead.

> Getting closer to rebuilding
> Joe Davis 

Regards,
rml
p.s. - oh wait! I was going to work on my cars this winter. :-0
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