In the LS world there is a plethora of cylinder head options for high-performance applications. Everything from upgrading factory heads to CNC-ported aftermarket cast heads and even billet heads. Part of the reason for so many options is due to the various LS engine designations. For instance, LS3 and LS7 engines have different intake flanges and bore sizes. So bolting better performing LS7 heads on an LS3 is not easily done — until now. Late Model Engines (LME) has released big-bore LS3 heads that are packed with LS7 cylinder head features.

Starting with a pair of CID six-bolt LS3 heads, Late Model Engines begins their process by deburring and removing any sharp edges befor running the heads through the CNC machine to port them to LME’s specifications. After the porting processes are complete the heads receive a competition valve job that is hand blended into the ports. These big-bore LS3 heads feature 298cc intake ports and 106cc exhaust ports. The cumbustion chambers on the heads come in either 65cc or 70cc, with custom volumes also available.

The interesting thing about the LME big-bore LS3 heads is they are designed for a 4.125-inch bore diameter and feature LS7 valves and rocker arm ratios. The intake valve is 2.250 inches in diameter, and you have a choice of either a lightweight hollow stem valve from Race Engine Valves (REV) or a titanium intake valve that includes a lash cap. On the exhaust side there is a 1.610-inch diameter Inconell valve from REV.

To complete the cylinder heads, LME will assemble them using either their own Platinum .660-inch lift spring kit or the PAC 1208X .700-inch lift spring kit. Other options include machining for 1/2-inch head bolts or studs, chamber softening, installing copper intake and exhaust seats, and machining receiver grooves into the heads.

When ordering the big bore LS3 heads LME will need to know your camshaft specs and rocker arm ratio. This lets the team at LME assemble your heads with the correct spring installed height in order to acheive optimal spring pressures and coil bind distance for maximum performance. For more information and to order your LME big bore LS3 heads visit their site here.