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High Oil Pressure for a 340 - What's Your Problem?

LS Chevelle Swap
Mark Shirley,
Orland Park, KS: I have a few questions concerning the engine I will be putting in my '66 Chevelle. I recently purchased an LQ9 from GM. I thought (and was told by the salesman) what I was buying was a new engine. After some part number searching, it appears I purchased a GM remanufactured LQ9. Will this motor be OK for a mild performance build? I have never purchased a remanufactured engine, and I am looking for the thumbs up or down. Secondly, if this engine gets the green light, I plan to leave the cathedral-port heads on and install a decent cam, full-length headers, duals, a TKO-600 trans, and a carb to start. As my budget allows, I'm planning on installing the FAST EZ-EFI system. I want to build a reliable engine with somewhere around 350 rwhp. Which upgrades will I need to achieve this? I was considering an '01 LS6 cam-or perhaps you have an idea. I also read that the pushrods are the weak link. I would like your suggestion on what components, cam, pushrods, and valve-springs to use (if needed) and their part numbers to facilitate this upgrade.

Jeff Smith: I called my pal Ken Casey at Burt Chevrolet in Englewood, Colorado, for the inside scoop on these engines. The LQ9 is the higher-compression (10.1:1) version of the LQ4 (9.4:1). Casey says the remanufactured engines have an outstanding warranty, which is exactly the same as new replacement engines: three years or 100,000 miles. Plus, if there is a part- or assembly-related problem, GM will replace the engine, including the labor. Of course, to keep the warranty, you can't change cams or cylinder heads, and we're not sure if the warranty holds true if you run a carburetor. But frankly, word on the street is that these engines are incredibly reliable, so I think you made the right choice.

The stock LQ9 cam specs out at 196/207 degrees duration with 0.467/0.479-inch lift and a 116-degree lobe-separation angle. The stock SAE power numbers are 345 hp at 5,200 rpm with 380 lb-ft. If you added a set of 13/4-inch headers, the power would improve slightly, although the cast-iron manifolds are very good for near-stock engines. Back in the Apr. '07 issue, we ran a test on a junkyard LQ4 6.0L ("480 HP for $3,775"). Right out of the box with a production cam, a GM Performance Parts single-plane intake, a Holley 750-cfm carburetor, and a set of Kooks 13/4-inch headers, the engine made 425 hp at 5,600 rpm and 439 lb-ft at 4,400 and 406 lb-ft at 2,200 rpm on Ken Duttweiler's dyno. Then we added a GM Performance Parts Hot hydraulic roller cam (219/228 degrees at 0.050 with 0.525-inch lift and a 112-degree lobe-separation angle). The bigger cam pushed the power up to 483 hp at 6,000 rpm with 450 lb-ft at 5,000 rpm, and torque was still 399 lb-ft at 2,200 rpm. This is awesome power for a near-stock 364ci short-block and would have a nice little lope to the idle as well. The GMPP Hot cam is PN 12480033. The cam PN is actually a kit that includes a set of LS6 valvesprings, which is why the price of the kit is around $500.

The stock production pushrods are a little on the spongy side, so a good replacement would be Comp Cams' 0.080-inch-wall-thickness Hi-Tech pushrods. The standard length for the 6.0L engine would be 7.400 inches (PN 7955-16, $115.75, Summitracing.com). I think you will be extremely pleased with the conversion in your Chevelle. Get it running by spring 2011 and bring it to our Engine Swap Drags event. As for the swap, I'm not sure if you will be using power steering. If so, you can get a conversion kit from Kwik Performance that will allow you to run an aftermarket accessory drive and clear the steering box. You'll also need a different oil pan. Perhaps the most affordable pan might be one from Champ Pans. The steel pan PN is LS1000 ($255.64 from Champpans.com), and it needs a separate pickup and oil filter adapter that bolts the filter directly to the pan. Most other aftermarket pans require a remote-mounted oil filter that adds to the overall price of the pan. You'll also need a motor mount swap kit. Generally, these are sold in conjunction with headers. As far as headers go, there are several companies making swap headers, such as Edel-brock, Hooker, Hedman, and several others. It would be worth the effort to check into the positive and negative aspects of each of these headers to make your decision. One thing to keep in mind is how far the header collectors hang down below the car. Not all headers are tucked up tightly against the floorpan like they should be. It's worth the effort to check into this.

More Info
Burt Chevrolet;
Englewood, CO; 800/585-4604; burt.com

Champ Pans; Eau Claire, WI; 715/834-7748; champpans.com

GM Performance Parts; Warren, MI; 800/577-6888; gmperformance parts.com

Kwik Performance; Springfield, MO; 417/ 955-1467; kwikperf.com

CC Quickies
We spotted this sleeper at Firebird Raceway at the starting line while the Junior Dragsters were running.

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