Brazilian GM 250 Engine, 4.1L, 12 Port Head
1995 to 1998 Silverado, 138 Hp, V8 bell housing pattern
1995 to 1998 Omega, 168 Hp, Opel 3.0L bell housing pattern
12 port engine, 6" rods, lighter piston with shorter compression height
Multi-port fuel injection, one piece rear main seal, cast dual exhaust manifold
Cylinder Head GM Part Numbers
93216528 Cylinder Head
93.238.389 Cylinder Head Complete
93.205.909 Cylinder Head Bare
Pistons, GM Part Numbers ('95 - '98)
93225129 Piston, 0.030 overbore
93225130 Piston, 0.040 overbore
Connecting Rods, 6", GM Part Numbers ('95 - '98)
93205918 Connecting Rod, 6"
The above is information I have collected over a period, some from this forum. Please confirm before ordering. The Brazilian parts are expensive, for whatever reason. The general tariff is supposedly approximately 30%. The Brazilian engine parts are 3 to 5 times more expensive than similar US engine parts. A pipeline to get Brazilian parts at reasonable price is an idea.
I'm personally interested in a real flat top cast piston, preferably hypereutectic. I searched the web and called Federal Mogul and others with no luck yet. The 307 "flat top piston", Federal Mogul 295AP, has very large chamfer around the top edge. This negates some of the effects of a proper quench. I assume this large chamfer was one measure to help reduce unburned hydrocarbons before the use of catalytic converters.
The 1968 and 1969 Pontiac OHC 6 250 had a real flat top piston, GM P/N 9784340,(a standard bore set is currently on sale on e:bay). The piston had deep valve reliefs, for a non-interfernce engine, incase the OHC belt failed. This piston is no longer available.
A 3 7/8" version of the 4" Federal Mogul H660P piston, flat top hypereutectic, for the Chevrolet 327 would be great (5.7" rod).
Path to photos of Brazilian Chevrolet 250 Cylinder Head:
http://www.goravenswood.com/links.htm / Engine / Entre / Cabecotes
Pontiac OHC 6 250 Flat top piston
e:bay Item Number 120320658687
