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Re: Cooling, Midget Kingpins, Stainless Studs

To: Bill Eastman <william.eastman@medtronic.com>
Subject: Re: Cooling, Midget Kingpins, Stainless Studs
From: EMILY COWEN <ecowen@cln.etc.bc.ca>
Date: Mon, 5 May 1997 10:51:42 -0700 (PDT)
Hi Bill Eastman!!

On Thu, 1 May 1997, Bill Eastman wrote:

> The reason that the intake hose is important for cooling an MG is that, if
> it is missing, cool air can bypass the radiator throught the hole.

What intake hose???  My '62 A mkII has one (sort of), but neither the
'71 GT, '73 B, nor the '74 B has one.  Are we missing some parts???

> I don't remember MGB's having a radiator fan shroud.  A shroud would help

The early ones didn't.  I can't speak for the post '74's.

> cooling at idle.  I know someone makes a shroud for an A, I would think

Yes, a shroud would definitely help the cooling at idle.  ANYTHING to
prevent the tip losses of the fan blades.  You want to prevent the air
from being recycled around the ends of the fan blades.

> bronze bushing can run fairly low clearance as long as they don't get too

When you size your bushings, the fit depends upon the method of
attaining the final dimension.  If you are honing to size, you want to
end up on the loose side of the tolerance, to allow for the passage of
grease for lubrication.  On the other hand, if you are reaming to final
size/fit, you must end up with a tight fit.  The reamer will chatter, no
matter what you do to prevent it, and the peaks of the chatter marks
wear off VERY quickly, leaving you with more clearance than you thought.

I know that there are specs to follow that give the two different
clearances, but I cannot lay my hand on them right now.

> I would not use anything but studs designed for heads or bearings in an
> engine.  The torque settings specified are unique for the material strength
> of the stud.  Changing to a different stud material would result in too
> much or too little stretch in the stud.  Too much stretch could fatique the
> stud leading to plastic deformation or failure.  Too little stretch could
> effect the ability of the stud to clamp over the wide range of temperatures
> an engine sees.  I would guess that stainless steel studs would be weaker
> than standard engine studs.  Using weaker studs would not be a good idea. 
> Notice that when you buy non-stock competition studs, they come with their
> own, higher torque recommendations.  This is to assure propper stud
> stretch.

If you new guys/gals can absorb what Bill has written, it will help you
to understand a lot of other concepts.
  
Stud/bolt stretch is what "locks" the fastener in position. Steel is
actually stretchy, and will try to return to it's normal length as long
as it is not stretched so far that it deforms.  That's why head bolts
don't need lockwashers... 

BTW, when torquing ANY bolts on your BMC engine, etc., ALL torque values
given are for LUBRICATED threads, NOT DRY.  105 ft/lbs on a dry thread
may only turn out to be 80 to 90 on a oiled thread, resulting in
insufficient fastener stretch to supply sufficient clamping force to the
joined parts; iow, your new head gasket still weeps...

TTUL8r, Kirk Cowen


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