<VV> 80 vs 84 vs 102hp head confusion

[Robert Jennings]

All parts that were machined from a casting or a forging had a unique number
for that casting or forging,  the 1st part made from that casting usually
had the next part number, 
GM part numbers were assigned without any meaning and were assigned in
sequence from a block of numbers assigned to the designing division.
Therefore if the casting or forging had more than one part machined from it
the casting number could not identify them.  And if the machined part has a
number only one digit away it probably is the 1st part machined from that
casting- but not necessarily.  If GM chose to identify the machined part
they would stamp a part number or code so that the assembly people would
know what part to use.
I worked for Saginaw Steering Gear from 1960 to 1978 in the Product
Engineering Dept.

Robert Jennings
317 Division St
Morenci, MI 49256
517-458-1586
jennirw at cass.net

-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Ramon Rodriguez III
Sent: Thursday, December 22, 2011 3:04 PM
To: virtualvairs at corvair.org
Subject: <VV> 80 vs 84 vs 102hp head confusion

Over on corvairforum.com someone asked about the difference between 80/84hp
heads and 102hp heads.  This wound up stirring up a lot of confusion.

I'll try to keep this simple and concise: (all this info pertains to the
1962/1963 engines)

84 HP engines were the "base" engine if the car was optioned with PG.  The
base engine with a manual trans was the 80hp.

GM advertised 80hp cars as 8.0:1 CR.  They advertised 9.0:1 CR on 84hp and
102hp

According to Clark's catalog 80hp and 84hp heads are the same heads which
does not fit with the above info

The info in the CORSA tech guide shows 80 hp heads and 84 hp heads as being
different designs.  It isn't entirely clear but the chart does not list
102hp heads and I think this is because they are the same heads as the 84hp
just with a different cam

The "Junkyard Primer" also seems to list 102hp head numbers that show up in
the tech guide as 84hp heads which fits with my guess, and lists 84 hp
heads that show as 80hp heads in the tech guide, furthering the confusion.




On a related note, the Tech Guide has two columns marked "casting number"
and "machining number".  The guide states that the casting number is the
one cast into the end of the head for reference and that the machining
number was used to order the item and would appear on the shipping box.
What is confusing here is that the numbers are very similar (example:
casting number 3817287 shows as machining number 3817286 off by just one
digit.  What really throws me here is that a lot of the head numbers listed
in the "junkyard primer" don't show up in the casting number column, but do
appear in the machining number column and seem to fit.  The "junkyard
primer" is meant for identifying parts, and it wouldn't make sense that the
numbers listed would not be cast onto the heads, but only on the box!

So first, can anyone confirm my belief that the 84hp heads are not the same
as 80hp heads but likely are the same as 102hp heads?  This means Clark's
catalog needs a correction if it is true.  Second, can anyone tell me what
is going on with the "machining numbers" in the tech guide chart matching
what should be casting numbers in the Clark's catalog and Junkyard Primer?


Thanks,

-- 
Ray "Grymm" Rodriguez III
Lake Ariel, PA
1966 Corsa 140 coupe (daily driver)
1965 Corsa 180 coupe (under construction)
1965 Corsa 140 coupe (for sale/under construction)
1963 Monza PG coupe (daily driver)
1962 Monza PG coupe (under construction)
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