For the uninitiated, peanut port refers to the small, oval-port heads used on the Gen-V 454 truck motors run prior to the introduction of the Gen VI in 1996. In addition to the less-than-ideal, peanut-port heads, the Gen-V motors were also saddled with hydraulic flat-tappet cams.
What are 781 heads?
The 781 heads are the best cast iron large oval port heads GM ever produced for the big block Chevy engine. They are worth rebuilding and respond well to pocket porting, bowl blending and larger valves. They will easily support over 500 horsepower. They are a very desirable street head.
Are big block Chevy heads interchangeable?
Mark IV, Gen V and Gen VI heads all have the same head bolt pattern, but they are not interchangeable due to different water jacket cooling passages.
How much horsepower can a 454 make?
Surprisingly, the 454 laid down an impressive 330 horsepower and 475 pound-feet of torque. Naturally, the truck-based 454s were tuned for torque, so having nearly 500 pound-feet wasn’t a big surprise. But like any stock engine, there was tons of power left to be squeezed out.
Which is better open or closed chamber heads?
Open and closed chamber cylinder heads differ in combustion chamber capacity. Although open chamber cylinders offer easier flow, the closed chamber cylinder is better for performance. Compression ratios are also affected by the size of the chambers.
Are 049 heads good?
For mild street and budget bracket big block Chevy 454, the factory iron 049 heads are outstanding; if they were cast in aluminum, they would be ideal. Big block Chevy 454 heads feature what are referred to as good and bad intake ports.
How do I identify my GM heads?
Chevy heads have often been identified by sight and most commonly by the different casting shapes on the ends of the cylinder heads. While these casting marks cannot tell specifics about the cylinder heads, they can help identify a performance head from a non-performance head.
What year did Gen 6 454 come out?
1996
Introduced in 1996 model year, the Gen VI features hydraulic-roller lifters, multi-port fuel injection, and a PCM.
What is the stroke of a 427 Chevy?
All 427s featured a 4.25-inch cylinder bore and 3.76-inch stroke.
