Not sure there is any one source of information on the GMC 302 on the web.
Here is a brief summary of what I know after building a couple of 302s and
buying and selling engines and parts over the years. The 302 was built from
1952 to 1959 as a military powerplant with 24V elecrical system and
accesories such as an air compressor, heavy duty hydramatic transmission and
large capacity sump. The civilian version was the same basic engine but
without some of the military accessories. All 302's are "square" engines of
4" bore x 4" stroke. Many of the parts used in the 228, 248 and 270 GMCs are
interchangeable, as these were all in the same family of engines. Factory
dyno tests under optimum conditions show about 170 BHP @3800 RPM with peak
torque of 265 lb/ft @2400 RPM. Advertised rating was 145 SAE hp with no
torque output specified.
These engines were only installed in GMC heavy trucks series 450 and up,
never in pickups or light commercial trucks. They were the standard
powerplant of the army "Deuce-and-a-half" 2-1/2 ton trucks and other
military vehicles.
When rebuilt with high-compression pistons, higher lift camshaft, multiple
carburetion and exhaust headers, a 302 GMC can produce 250-270 HP and 300+
lb/ft of torque pretty easily with no loss of reliablilty. Because of the
heavy crankshaft and long stroke, these are not high RPM engines and radical
camshafts are a waste of money. The 302 is a torque motor. 5000 RPM is
attainable but the engines are most comfortable at 4500 or less.
302 engines are not difficult to find, but most local boneyards never saw
any, because they were only found in heavy trucks. The engines sometimes
show up on Ebay, in the classifieds at www.stovebolt.com and
www.inliners.org , and there are persistent rumours of miltary surplus
caches with vast supplies of NOS 302 engines. If this turns out to be true,
they are probably being guarded by Elvis.
Jack / Winter Park FL
----- Original Message -----
From: "Scot Stockton" <auriclux@usa.net>
To: <oletrucks@autox.team.net>
Sent: Friday, June 28, 2002 6:28 PM
Subject: [oletrucks] 302 in-line 6?
> I was talking to an engine builder today and he mentioned the GMC 302
in-line
> 6.
>
> I don't know much about this motor - can anyone point me to a source of
info
> on it? Preferably on the net.
>
> If I end up looking for one, how hard are they to find?
> 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
|