July 2011 Chevy High Performance Q&A

Kevin McClelland Jun 6, 2011 0 Comment(s)
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LS Engine Heaven

1107chp 01 O  July 2011 Performance Q A Engine Drawing 2/2

Last month I wrote about finally finishing my Super Gas roadster and having a great first outing at a local race in Fontana, California. Now, the garage is full of LS engine parts. As I mentioned several months ago, my son, Daniel, is installing an LS2 in his ’94 Mazda RX7, but the motor was dead on arrival. We were originally hoping to swap out some performance parts and drop it right into his car; the engine was from a 42,000-mile ’06 GTO that looked like the oil had never been changed, and it was on its second set of tires that were bald when we got it. Once we pulled the engine apart, we found that the top of every cylinder was out-of-round and was letting a tremendous amount of cylinder pressure past the rings; not only were compression gases going past the rings, a ton of oil was getting into the combustion chamber.

To remedy this, we picked up a complete 4-inch stroker kit from Livernois Motorsports. They use only high-quality Callies forged crankshafts, H-beam rods with ARP 2000 bolts, Diamond pistons, Total Seal rings, and Clevite Tri-Armor Coated Bearings. We’ve mic’d all the critical dimensions and everything was dead on spec. We’re currently in the process of fitting the rod and main bearings to bring the oil clearance at 0.0025 inches on the rods. We did experience a minor setback when we went to set up the mains. After installing the ARP main stud kit and torquing everything, we used our dial bore gauge to make sure that the main housing bores were within spec. We should have expected it since we knew the condition of the GTO, but the main housings were 0.001 inch over the maximum tolerance and worse yet, the rear main was over 0.001 inch out of round. We ran the block out to Jim Grubbs Motorsports last week for a quick align hone to bring the main bore into spec and to hone the block out 0.005 inches to match the oversized pistons. At JGM, they have gone through the expense and trouble to use two torque plates on all eight cylinders to fully stress the tops of the cylinder block before honing to ensure perfectly round cylinder walls for great ring seal.

With my roadster out of the way it’s time to get the 6.2L L92 into our Malibu wagon. I’ve already ripped the heads off, picked up a full set of Manley hollow stem valves, and sent the heads off to get CNC ported; we baselined the stock heads on my flow bench and I can’t wait to see the increases with the porting. I have the engine swap kit and headers coming from Muscle Rods, and all the oil system components needed coming, so between Daniel’s engine and the wagon repower, we’re going to be burning the midnight oil. Come by and check to see if the lights are on.

Too High

Q: I am swapping out my 396 ci with a 496ci big-block in my ’69 Chevy Camaro. The old engine header tubes on the driver side are partially collapsed to allow clearance from the steering box. I decided to buy new headers for the fresh engine and was informed that the headers should not have to be modified whatsoever to clear the steering box. As a side note, I think the original engine was a small-block. I was also told that the current 396 ci is probably using the small-block motor mounts that came with the car. That said, I purchased new engine frame mounts and made sure they were correct for the big-block. The old frame mounts are in a different set of holes and I see the hole that lines up with the new frame mounts. My question, or problem, is that the new big-block mounts are two different sizes; one is taller than the other that mounts to the frame of the car. What side gets the taller mount? Is it the driver side or the passenger side?

Dave Mock
Via email




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