Water Pump LS3 vs LS7

[James]

It's not the most glamorous topic but here is the question.

I need to purchase a new water pump regardless. Is there a difference in fitment for the LS3 vs the LS7? According to the SLC Builders Wiki page the LS7 pump is preferred because it is slimmer and provides a little more clearance from the chassis. Is this correct? And it looks like from 2009 on the LS3 and the LS7 are the same? Is there that much of a diffence to make it work searching for the LS7 pump? Thanks in advance for the help.

 

[Howard Jones]

I thought for a while if my water pump on my gen 1 SBC has ANY issues I'm changing the setup to a electric pump. Something to consider. The Davies Craig Units are really getting much more longer lived and from what I have learned work really well with the electronic controller. Takes all the water pump stuff off the front of the engine and puts its where ever you like.

Just a little different idea.

 

[James]

I've thought about it, but just having a hard time justifying the $400 cost for the 8hp or so benefit. True, it makes it easier to mount and allows for more flexiblity.

 

[Alex]

either works fine. fitment is irrelevant, they're both going to be tight at the tightest point. I think LS3 is the easiest to route the hoses to (avoiding making the hose a high point in the system)

 

[Ken Roberts]

The older LS3, LS7 and LS2 water pumps (08 and earlier) had the outlet on the passenger side. The newer LS3 and newer LS7 water pumps (09 and up) have the outlet on the drivers side. The thermostat housings and thermostats changed slightly between the older and newer versions and are not interchangeable. Physically the older and newer pumps share the same dimensions.

Your decision on which one to use should be based on your belt wrap for the accessory drive you use.

Here is a great deal on take off pumps (newer style)

Without thermostat and t stat housing.

LS3 LSA L76 LS7 Water Pump New Take Off | eBay

With thermostat and t stat housing.

LS3 LSA L76 LS7 New Water Pump | eBay

 

[Randy]

I just did a new LS3 and it is unique. I solved my belt- alternator problems by having a clockwise rotation impeller replace the reverse rotation impeller then I had no idlers and a simple water pump -crank pulley- alternator- belt Like an old sbc. I like simple!
Randy

 

[Alex]

I just did a new LS3 and it is unique. I solved my belt- alternator problems by having a clockwise rotation impeller replace the reverse rotation impeller then I had no idlers and a simple water pump -crank pulley- alternator- belt Like an old sbc. I like simple!
Randy

that's an awesome idea - if I'd known you could have done that i would have gone that route for sure.

 

[James]

I just did a new LS3 and it is unique. I solved my belt- alternator problems by having a clockwise rotation impeller replace the reverse rotation impeller then I had no idlers and a simple water pump -crank pulley- alternator- belt Like an old sbc. I like simple!
Randy

Pictures Man,, Pictures....lol.

 

[Eric Teeter]

One thing I heard was that at a stoplight the LS has an overheating problems in the LS, I believe because of pressure looses.

LS3 & LS7 Pumps Below left two

As you can see those that come from the factory seal off the out let and weld on at sharp 90 deg. You can see that makes 2 sharp 90 deg bends right next each other. They are just on one side or the other of the pulley.

The way the factory center right

I found that the truck engine has no sharp bend in the fluid, if they just cut the outlet and rotate the direction needed. The piping would be behind the belts. And would increase the flow of water help to reduce the over heating problem. This pump is less than $60.00 from RockAuto.

Truck pump is far right.

When I build mine I would use the 5.3L truck pump.

Just my two cents worth.

 

[Ken Roberts]

Unfortunately the truck pump has the wrong belt offset. The pulley sticks out much farther and will contact the aluminum firewall crossbeam. You can only use the Corvette offset (short) drive setup..