A four-seven firing order swap is becoming an increasingly popular upgrade for engine builders looking to squeeze more performance from a Small Block Chevy engine.
Never heard of it? Basically, instead of the traditional 1-8-4-3-6-5-7-2 firing order, the four-seven swap makes it 1-8-7-3-6-5-4-2.
Thanks to benefits like better mixture distribution, when you change the cylinder pairing from 5/7 to 4/2 it can help you pick up more power in the midrange and a small amount up top with no other changes.
There are other factors to consider too, like camshaft loading and heat management.
For instance, by moving the adjacent firing cylinders nearer to the water pump, it means the combustion chamber stays relatively cooler, allowing you to run slightly more timing without detonation. The swap can also reduce cam twist from front to back—with the adjacent cylinders firing nearer to the front of the engine (and timing chain), you’ll mitigate valve timing fluctuations.
Want even better news? Summit Racing’s got a new series of Pro 4-7 Swap Hydraulic Flat Tappet Camshafts for the Small Block Chevy that’ll help you make the 4-7 switch.
Available in tiers from Stage 1 to Stage 8, these 4-7 Swap Cams are perfect for virtually any SBC performance scenario, including mild street machines, aggressive dragstrip monsters, and seemingly everything in between. Get all the specs on each one by clicking the part numbers below: