Chevy LS Intake Manifold Clearance Issues: How to Fix Them

Swapping in a large performance intake manifold — like the Fast 102mm — on a Chevy LS engine is a popular and straightforward upgrade. But there's one common wrinkle that catches builders off guard: the large intake flange can interfere with the stock LS1 water pump.

Where the Interference Happens

The clearance issue occurs at the top of the LS1 water pump, specifically at the top bolt that holds the backing plate onto the water pump. When a large-flange intake like the 102mm Fast is installed, this area conflicts with the intake casting. There are three ways to address it:

Solution 1: Light Grinding (Budget Option)

If you're on a tight budget, you can do some light grinding on both the intake and water pump to gain the required clearance. This can work, but proceed carefully — you don't want to weaken the bolt boss too much or damage the intake manifold sealing surface. We do not recommend this approach for making a CVF kit work.

Solution 2: Swap to an LS2 Water Pump

The cleanest budget fix is to upgrade to an LS2 water pump. LS2 pumps do not have a bolt-on backing plate, so the casting lump that causes the interference simply isn't there. Key specs to know:

• LS1 water pump: 7-1/16" tall (5-1/4" to the front of the belt surface)
• LS2 water pump: 5-1/4" tall (4-3/4" to the front of the belt surface)

The LS1 and LS2 pumps are otherwise interchangeable. The LS2 pump being shorter is actually a bonus — it gives you a bit more radiator clearance. Just make sure your front accessory drive system will still line up correctly with the shorter pump. Note: CVF Racing does not carry the LS2 water pump.

Solution 3: Upgrade to a CVF Wraptor Serpentine System with Edelbrock Pump

The best long-term solution — especially if you're already planning a full accessory drive upgrade — is to go with one of CVF Racing's Wraptor serpentine systems paired with the Edelbrock water pump option. The Edelbrock pump is sold separately but offers plenty of clearance for large intakes.

If you go this route, give us a call and we can build a custom cart for you — we'll remove our standard water pump and swap in a different water pump pulley to account for the Edelbrock pump's flange height. Call our free tech support line at 651.356.8593.