502 and 540 Big-Block Engine Comparison - Big-Timer

Bored & Stroked: 502 vs. 540

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Cylinder Heads: Bow Tie 502

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For baseline runs of the freshened 502ci mill and stroked 540ci engine, we utilized a set of GM ZZ502 cylinder heads (PN 12363392). They come with 290cc oval intake ports and 110cc exhaust ports with equal-sized combustion chambers. While they can be purchased complete as off-the-shelf pieces from GM, JMS Racing performed a small valve job by installing larger, 2.250/1.900-inch intake/exhaust valves and heavier-duty COMP dual valvesprings.

Cylinder Heads: Dart Pro 1

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While we got our set from Dart Pro 1 cylinder heads as a bare set, Aerohead Racing Components performed the custom assembly for our 540ci stroker build. Race-proven features and affordable pricing make these Dart Pro 1 355-T6 aluminum cylinder heads one of the biggest values in racing. The Pro 1 cylinder heads feature 119cc combustion chambers and larger, 325cc intake runners with 129cc exhaust runners. Aerohead’s team added 2.300/1.880-inch intake/exhaust stainless steel valves, Aerohead spring cups, hydraulic roller 1.550-inch dual valvesprings (354 lb/in), and 10-degree split locks with Viton seals. ARP 7/16-inch rocker studs were also installed along with Dart adjustable guideplates.

Holley 950 HP

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Holley’s HP-Series carburetors include updates to their traditional line of 4150-style pumpers. These updates include cast main bodies without choke horns and smoothed venture transitions for increased airflow. Since they’re aimed directly at optimizing power and performance for racing applications, other important modifications include screw-in air bleeds, stainless steel throttle plates, and notched floats. Holley also has Dominator-style fuel bowls to allow fuel line plumbing from either side. All of our 502ci and 540ci testing used the 950 HP for dyno pulls at JMS. CHP

Sources

Proform Parts (Specialty Auto Parts U.S.A.)
Warren, MI 48089
586-774-2500
http://www.proformparts.com
Chevrolet Performance Parts
Detroit, MI 48232
800-577-6888
www.gmperformanceparts.com
JMS Racing Engines
El Monte, CA
626-579-4567
http://www.jmsracing.com
TCI
Ashland, MS 38603
888-776-9824
www.tciauto.com
Hot Rod Specialties
909-931-7440
http://www.rodeswayboats.com
Dart Heads
Troy, MI 48084
248-362-1188
http://www.dartheads.com
Aerohead Racing Components
317.862.0223
www.aeroheadracing.com
Northern Auto Parts
800.831.0884
www.northernautoparts.com

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