April 29, 2021

Linkage Mag

Geared for the Automotive Life

A Problem with Parts

Craigslist, Facebook Marketplace and my father are all bad influences.

This problem started three years ago, when I was building a ’79 Chevrolet C10 and I decided that I needed a different set of cylinder heads for my LS engine. 

The engine was 6.0L out of a 2004 GMC truck. Stock, it had a truck-friendly 9.4:1 compression ratio. In the hunt for power, I’d already swapped out the original dished pistons for a set of flat-tops to boost compression up to about 10.1:1. More is better, right? 

The factory “317” truck heads flow well but have big chambers — but I’d learned that “799” heads, used on LS2s and some 5.3s, have smaller chambers, so I figured that would be the hot ticket. Stock bore, flat-top pistons and 799 heads all added up to a hot 11:1 compression ratio in my 6.0. That’s muscle car territory!

So I found a set of 799s for sale on Facebook Marketplace and drove across town to buy them. The trouble was that the seller also had an LS6 camshaft out of a 2002-04 Corvette Z06 and would only sell the heads and cam together. I didn’t need the cam for my 6.0, but I brought it home anyway.

GM “5308” is the 2002-04 LS6 cam — and the root that started this project.

Since then, it’s been sitting on my garage shelf and rumbling in the back of my mind.

Here’s the problem: I was an active drag racer in the early 2000s, and I vividly remember how much of a game changer the LS6-powered C5 Z06 Corvette was. Prior to that, my 12-second Caprice tended to be faster than the newer cars that came to grudge race, save for Dodge Vipers. The Z06’s LS6 engine was based on the LS1, but it had better heads and a more aggressive camshaft. It changed everything when it hit the scene, and it proudly wore little “405 hp” LS6 fender badges that warned others of their imminent loss. It left a big impression on me.

That brings us to this past weekend. My father, who is now retired and therefore free to browse Craigslist all day, calls me up. He doesn’t even say hi.

“LS1. Broken piston. $100. It was just posted three hours ago.”

The LS6 cam in the back of my brain popped to the front. How do you build your own LS6? You do it with an LS1 block, an LS6 cam, and some LS6 heads. $100 and a cam I already have gets me halfway to glory. Irresistible.

Next thing I know, I’m dialing the seller to buy a greasy broken engine that I wasn’t looking for and don’t need.

“It was in a road race Corvette.” said the seller the next morning as I stuck a finger through a hole in the #7 piston. “We tried to install a new timing set and the marks were set up wrong. Cranked it over and it was carnage. We needed to get back on the track, so we just stuck an LS3 in it.”

Hmm. Now what?

$100 later, I had this mess of an LS1 leaking oil and coolant in the back of my truck. Dad came by later to survey the carnage, and now that it’s torn down, I can tell that I have a good crank, good rods and a block that just needs a basic hone.

For now, it’s all going on the shelf and I’m going to put my phone in a drawer for the rest of the year. 

Anybody know of any LS6 heads for sale?