Bob,
Thanks for the nice pictorial guide to the HiPo. I will include this in
our TigersUnited.com links section.
However, it is possible that the reader can be somewhat confused by one
of the statements made about the crankshaft.
While it is a correct statement that "The HiPo crankshaft was an
ordinary cast iron 289 crank, no special machining was claimed.", it is
misleading.
Yes, the crankshaft was one of the regular production crank runs,
HOWEVER, after the crankshafts were heat treated, a number of them (if
not all) were tested for hardness with a brinell tester. This hardness
is a measure of the structural tensile strength of the part, as a result
of the heat treatment. Those that were found to be at the high end of
expected tolerances were set aside, marked with orange paint, and
destined for the Hi Po assembly line. This does NOT mean that cranks of
equal, or near the high range were not put into the normal engine when
the quantity needed for Hi Po's was achieved. They just weren't marked
orange, but some excess selection could have been re-allocated to
standard production. It was just a "selected" stock crank at the high
end of production variation.
I am unsure whether ALL crankshafts were routinely quality control
tested for heat treat hardness. It would have been had it been for
military use. A small flat ground spot on a counterweight would have a
few small dimples on it from the tests. Much like a fine point, spring
loaded center punch. Of course it was a much more sophisticated piece of
equipment, but the depth of penetration with a preset impact is what the
criteria is for hardness, which equates to the crank tensile strength
from heat treat.
Steve
Bob Palmer wrote:
>Paul,
>
>The simple answer is, there is no difference; at least the blocks all
>started out the same. The story is that the HiPo blocks were hand picked for
>cylinder wall thickness, etc. The difference is in the machining of the
>blocks; bigger main caps, screw-in oil galley plugs, etc. Here's a link to
>rundown of the HiPo block's unique features.
>
>http://members.tripod.com/lyc_42/fordv8/hipo/hipo.htm
>
>Bob Palmer
>rpalmer@ucsd.edu
>rpalmer@brobeck.com
>
>-----Original Message-----
>From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net]On
>Behalf Of ZUKPJ86@aol.com
>Sent: Friday, October 11, 2002 3:41 AM
>To: tigers@autox.team.net
>Subject: Surfire way to tell a 289 HP block
>
>Hi all,
>Can anybody recommend a surfire way to tell a bare 289 HP block
>from a standard 289?. What are the differences?
>It seems Tom Monroe's "How to rebuild a small block Ford" lists the same
>casting numbers for both.
>
>Thanks.....Paul (now at the restoration point of no return)
>
>
>
--
Steve Laifman
Editor
http://www.TigersUnited.com
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