325 Chevy Small Block Engine - Bolt On A Cam And Heads And Add 120+HP

The stock 5.3L head is virtually a clone of an LS1 casting using smaller valves. Richard Reyman at West Coast Racing Cylinder Heads pocket-ports the intake and exhaust to Stage 1 specs with slightly larger valves while leaving the chamber stock.

The stock 5.3L head is virtually a clone of an LS1 casting using smaller valves. Richard R

Talking Heads
You've probably already skipped ahead to the dyno test numbers, so you know how well our little junkyard dog performed with just a cam and head swap. As we mentioned earlier, the big reason a stock 5.3L does so well with just a cam change is all due to the heads. A stock 5.3L cylinder head uses a similar port configuration to a 5.7L LS1 engine with a slightly smaller (1.89- vs. 2.00-inch) intake valve. As you can see by our flow numbers, even a stone stock 5.3L casting can produce 219 intake cfm at 0.500-inch valve lift. That is more than most production Gen I heads (except for the iron Vortec). On the exhaust side, the story is even better. The stock 5.3L exhaust-port numbers are far higher than all Gen I production heads. In fact, you have to get into expensive aftermarket Gen I heads in order to better the stock exhaust-port flow on this 5.3L head. This is the main reason why this engine makes such good horsepower at the higher engine speeds.

Reyman buys semifinished Edelbrock castings for his fully CNC-machined 200cc version. The ports are purposefully tiny and the bowls are almost nonexistent to give Reyman plenty of room to create his own CNC port.

Reyman buys semifinished Edelbrock castings for his fully CNC-machined 200cc version. The

While doing our research, we ran across Richard Reyman's West Coast Racing Cylinder Heads company, which has been quietly working on porting the stock 5.3L cylinder heads. He hand-ports the intake and exhaust bowls and adds slightly larger SSI 1.94/1.57-inch valves. As you can see from our flow bench reports, Reyman's deft touch with the grinder combined with larger valves is worth impressive gains throughout the entire lift curve with a massive intake port flow gain of 37 cfm at 0.500-inch lift to 256 cfm. That's roughly the equivalent flow to a high quality aftermarket Gen I head. Remember, this is just larger valves and a bowl job on otherwise stock heads. On the exhaust side, he gains an impressive 23 cfm for a total of 198 cfm from 175 cfm stock. Those are outstanding exhaust flow numbers.

Before the first head hits the CNC machine, Reyman designs the ports on a solid modeling computer program. Once the ports are perfected, the program is loaded into his CNC machine and then the fun begins.

Before the first head hits the CNC machine, Reyman designs the ports on a solid modeling c

But Reyman doesn't stop there. He also sells CNC ported heads, which start out as a semi-finished Edelbrock casting and are whittled out using 2.00/1.57-inch valves and a 58cc chamber. All this work pushes the flow up to an impressive 267 cfm at 0.500-inch lift when tested on a 3.780-inch 5.3L bore size. Compared to the stock head, this is a significant gain of 48 cfm (22 percent) at 0.500-inch lift, but the gains are also evidenced again throughout the entire lift curve. Once we evaluated all three sets of cylinder heads, it was time to bolt 'em on the engine and see what they would do.

By Jeff Smith

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