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LS water pump spacers let short car water pump work with long truck front drives

QUESTION

I have a 6.0L LQ4 engine out of a 2005 3/4-ton Silverado that I am installing in a 1957 Chevy Bel Air. The outlet on the water pump comes up and forward. It looks like the outlet on GM pump PN 12682286 (_sic_) might work better. Can you tell me if this pump would work on my engine?

_John Hanna_

ANSWER

John, car-type LS pumps have front exits, but other parts, includingLS water pump spacers, may be necessary to make them work, depending on the parts you already have. Let's take it from the top: First, your above-referenced part number does not exist within the GM parts system. You probably meant PN 12681186 (casting No. 12681180), which is stock on 2005—2007 LS2, 2008 LS3, and 2007—2008 LS7 Corvette engines.

The What to Do if You Don't Already Have All the Truck Accessory Drives Solution

Although its passenger-side, front-exit outlet hose barb angle seemingly works better on many retrofit engine swaps, the"Corvette" LS2 water pumps are about 1-9/16inches shorter than "long" truck pumps.The pump and its permanently attached pulley will bolt up to the truck block, but that pulley won't line up with the crank pulley that's machined into the harmonic damper. All Gen III and IV "LS"-type small-blocks are internally balanced, so you could install, for example, a Corvette LS2 damper with its integral pulley (GM PN 12675715) onto your crank without any engine balance issues.

Installing an LS2 Corvette pump and a Corvette LS damper assumes you don't have any other accessories, brackets, and pulleysyet because—with just production-based parts—the short pump and balancer require corresponding Corvette-type accessories, mounting brackets, and pulleys to get everything properly lined up (including the A/C compressor, power-steering pump, and alternator). There are also various aftermarket drive solutions available from outfits like Holley and KWiK Performance, some of which are compatible with both a short pump and the existing truck harmonic balancer.

Butwhat if you already have all the truck drives and accessories?They sure won't line up with a Corvette water pump and balancer!Are there affordable solutions that don't involve changing out the entire stock front drive system?

You betcha! Here are several:

The Nearly Free, Do-It-Yourself Solution

Mod the existing truck water pump.This only works with some auto parts store universal replacement pumps, such as Duralast PN US64-T (online price, $119.99). On this pump and some other universal parts-store pumps the casting has an extra blank boss on the front-passenger side. Drill and tap the blank boss for a pipe thread fitting that matches the outlet hose diameter. Pipe elbows are available if needed for any clearance or hose-routing issues. Use a slide-hammer, large vise grips, or similar tool to pull out the old, now-unneeded, vertical fitting, then plug the open hole with an appropriate-size cup-plug or drill and tap it for a pipe plug.The cost: Virtually free if you already have one of these "universal" pumps, except for your time and the appropriate-size drill bit, pipe tap, plug, and pipe fitting. Don't want to take the risk? Try this:

The Elegantly Simple, Make an Early LS Short Water Pump Work Without Buying a Whole New Drive System and Balancer Solution

Buy or fab LS water pump spacers!One aftermarket source is Dirty Dingo Motorsports, which sells an LS1 water pump spacer kit (PN DD-LS-WP-SP1, $49.99) that moves an early short Corvette LS pump forward 3/4 inch to line up with the existing truck crank and accessory pulleys.

Dirty Dingo's kit requires the use of an early short LS1 pump.Not the LS2 pump referenced at the beginning of this answer,the recommended pump for Dingo's kit came stock on the 1998—2002 Camaro/Firebird, 1997— 2004 Corvette, and 2004—2006 GTO. It has a broad, bell-like pulley, which is why—in its OE application—it works with both the Corvette and Camaro Gen III front-drive system, even though the original applications used slightly different-length balancer pulley offsets. This pump won't work on later engines with VVT (variable valve timing; not applicable to your 2005 6.0L LQ4 engine), because the early pump with spacers won't clear the bulged VVT front cover. Due to slight alignment and bolt-pattern differences,also mandatory with this conversion is a new 1998—2002 Camaro/Firebird (notCorvette or GTO) tensionerand bracket assembly.

If you insist on using the Corvette LS2 pump, a similar spacer concept could conceivably work, but the spacers need to be much thicker, around 1-9/16 inches. KWiK Performance says the LS2 pump with such thick spacers would working using Gates tensioner PN 38323 off a weird Mopar application.

The What to Do if Running a "Short-Height" Car-Type Intake in Place of the Tall Truck Intake Solution

The methods discussed so far may not always work for those hot rodders who have a truck long-pump system but can't use the truck water pump with its straight-up outlet fitting due to throttle-body clearance/interference when installing lower car-type LS intake manifolds in place of taller truck LS manifolds. If that's the case, consider the2010—2015 Camaro water pump,whose water outlet also comes straight out the front, but on the passenger side. Unlike the LS3 Corvette short pump (which also has a driver-side outlet but still needs spacers), the late Camaro uses a "long" pump, with the correct belt spacing to match the truck balancer and clear the car-type inlet manifold throttle body and ducting without spacers.The problem is passenger-side, front-outlet, pumps—whether late Camaro or 'Vette LS3—run into the truck drive system's idler pulley on the passenger side between the water pump pulley and the alternator.If that occurs, you need tomove the idler further toward the passenger side using Dirty Dingo idler pulley relocation kit PN DD-LS-IRB. The relocation also requires hacking off the original idler pulley mounting ear on the truck's big alternator bracket plus a different-length serpentine belt.

Be Sure the Thermostat and Housing Match the Water Pump

One more tip:Over the years, there have also been different thermostat housings and even thermostatsthemselves—not just the hose angle and opening temperatures, but in some instances actual physical envelope and seal changes. If your truck housing and thermo won't fit, get the equivalent matching parts for the water pump you are installing.

How to Run Front-Exit LS Water Pumps With Truck Balancers and Front Drives

• For a passenger-side front exit, run early LS1 Camaro/Corvette short water pump with Dirty Dingo 3/4-inch spacers and the LS1 Camaro tensioner or the later LS2 Corvette short water pump with 1-9/16-inch spacers and Gates tensioner PN 38323.
• For a driver-side front exit, run a 2010 to 2015 Camaro LS3/L99 water pump with no spacers, trim off existing truck idler pulley mounting ear, and move the pulley further toward the passenger side.
• LS thermostat housings and thermostats vary by angle, configuration, sealing gasket, and design—be sure they match the new pump (some new pumps include these items).