Looked through the 1955 2nd through 1960 GMC Master Parts Book last
night and found that the same head (part number 2334620) was used on 248
and 270 engines while the 302 used a head with part number 2334624.
Note that these are NOT casting numbers. The intake and exhaust valves
are the same for the 248 and 270, different for the 302. The two heads
do use the same cam, valve springs and rocker assemblies. The 270 and
302 use the same crankshaft.
The shop manual does not list the size of the valves, but does show that
the angle on the seating surface of the valves is 45 degrees on one (the
302 if I remember right) and 30 degrees on the other.
Sorry I couldn't find actual valve sizes.
-----Original Message-----
From: Williams Grant Civ AFRL/Det 2
[mailto:Grant.Williams@kirtland.af.mil]
Sent: Tuesday, November 27, 2001 8:18 AM
To: oletrucks@autox.team.net
Subject: [oletrucks] GMC - Large valve inliners
Does anyone out there know how to determine whether a GMC 270 or 302
head,
has the large valves without removing the head? Engine type is easy;
although if it has been swapped to another vehicle, I'm not sure how to
tell
what year it is. I believe all the 52-59 302s had the large valves, but
not
sure about the 270s.
Grant Albuquerque, NM
1950 GMC 100
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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