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LS Intake Manifold Clearance Issues

Installing a large intake manifold like the Fast 102mm intake on a chevy ls engine is pretty straight forward but there are a few small wrinkles that you need to account for. The one we see most often is that the large intake flange can sometimes interfere with a stock LS1 water pump. The interference occurs at the top of the water pump with the top bolt that holds the backing plate onto the water pump. (See Photo to the Right) Fast 102mm Intake with LS1 Water Pump Interference

There are a couple of solutions to this issue.

1) If you are on a budget, you can simply do some light grinding on both the intake and water pump to gain the required clearance. Just be careful not to weaken the bolt too much or damage the intake manifold sealing surface.

2) You can change to an LS2 water pump. LS2 water pumps do not have a bolt on backing plate so this casting lump isn't an issue and you will have plenty of clearance. The LS1 and LS2 water pumps are interchangeable except that the LS2 water pump is much shorter. This can be a good thing though because it will give you a little more radiator clearance. You will need to make sure that your front accessory drives will still line up correctly. LS2 water pumps are 5 1/4" tall (4 3/4" to the front of the belt surface). LS1 water pumps are 7 1/16" tall (5 1/4" to the front of the belt surface). So, if your belt is running near the back side of your LS1 water pump then you will be ok, but if your belt was running on the middle/front of your LS2 pulley then you will need to upgrade your front accessory drive system (option 3 below)

3) Another solution is to upgrade to a new LS serpentine drive system using a different water pump. We recommend using one of our Wraptor serpentine systems with the Edelbrock water pump option. The Edelbrock pump is sold seperately, but it has plenty of clearance for your large intake. (See Photo comparing LS1 water pump with Edelbrock Water Pump)

Edelbrock LS water pump vs Factory LS1 Water Pump