A few months ago in our March '09 issue, I introduced the 5.3L LS Chevy engine I was planning on dropping in my '72 C-10. For those who missed it (you may need to find a back issue to get up to speed), I went to Dave's Goldenwest Truck, a local Orange County, California, wrecking yard, and picked up a 5.3L engine that was from an '01 Suburban. I took the engine to Turn Key Engine Supply in Oceanside, California, so they could walk us through what it takes to get rid of all the non-important stock pieces. This wound up being quite the striptease, which included the stock EFI harness. Turn Key makes their own neat and compact harness for LS engines that simplifies the whole shootin' match, not to mention their cool layman's version of a fuel system for non-stock applications.
This was all fine and dandy, but I knew I was going to have to hunt down a few more items before pulling the very tired old small-block out of the truck. The stock radiator had seen better days and had started acting up, so I ordered an aluminum Griffin radiator from Southern Rods and Parts along with two 14-inch electric fans that fit perfectly in the width of the radiator core. The Turn Key harness comes with another mini-harness for two electric fans and the fuel pump, so I didn't need anything additional there. Turn Key also provided the LS engine mount adapter plates. These allow the transmission to stay in place and the LS engine to drop onto the stock engine mount location using the old-style rubber mounts. Headers were another "maybe" as far as what I needed, but Sanderson Headers had a late-model LS truck shorty version for me to try out.
Obviously the old engine needs...
Obviously the old engine needs to come out, but there's plenty to be done before grabbing the cherry picker. This entails the radiator, throttle linkage, wiring, and disconnecting hoses.
For most of you, this would be what's needed for the majority of the initial LS conversion, but of course nothing is easy for me. A few years ago I found out that my C-10 had the engine mounted in the rear of two possible positions, but most `67-72 C-10s I've seen since have their engines in the forward position, 4 inches forward to be exact. I was hoping the LS engine would also fit in the rear location that my 350 was in, but in the back of my mind I knew it wasn't gonna happen--if for no other reason than Murphy's Law, which proved to have the upper hand. So, I went over to Classic Performance Products and got a set of their tubular motor mounts that replace the stock, forward-position, stamped-steel mounts. No, biggie, but this also meant I'd have to move the transmission crossmember, mess with the shift linkage, and get a longer driveshaft.
The other part to the install was getting the LS engine to work with the non-electronic 700-R4 trans already in the truck. I got the transmission from Gear Star a few years ago and have been nothing but pleased with it, thus wanted to keep it in the truck in lieu of going to a modern electronic overdrive automatic like what would have been behind the 5.3L from the factory. This shouldn't be a problem, but there are two things that need to be taken care of: the TV cable and the installation of a spacer between the crank of the LS and the torque converter of the 700-R4. The latter of the two is easy thanks to Turn Key having the adapter that taps into the back of the crank. The matter of the TV cable I'm still working on, but should have it figured out for next month's hopeful LS conversion conclusion, which will also cover the fuel system, exhaust, and final wiring. Hang in there!
 Many can get away with modifying...  Many can get away with modifying their existing exhaust, but I'll be totally redoing mine. The long headers come out easier from the bottom. The motor and tranny mount bolts need to taken out as well as the driveshaft removed. |  At last count, I was getting...  At last count, I was getting about 9 mpg ON THE FREEWAY with the 700-R4 and a 3.42:1 ring-and-pinion, which was appalling to say the least. Plus, recalling the last dyno, it had but a mere 113 hp at the rear tires. It will be interesting to see what the LS can do. |  After installing the crank...  After installing the crank spacer into the back of the crank, bolting the torque converter to the LS flex plate, and mating the LS engine to the transmission, I installed the Sanderson headers. This is all mock-up at this point to make sure everything is going to jive; later I'll add the gaskets and the rest of the header bolts. |
 The motor mount adapter plates...  The motor mount adapter plates simply bolt to each side of the block. Next, the traditional small-block rubber mounts get bolted to the adapter plates. |  The moment of truth (or fiction)...  The moment of truth (or fiction) was soon upon me as I lowered the freshly joined LS/700-R4 combo into the engine bay of the '72. |  As I mentioned earlier, the...  As I mentioned earlier, the engine in my truck was set back farther than all of the C-10s I'd seen. The stamped-steel mount bracket is obviously an OEM piece, but I don't know what the reason is. At any rate, most small-blocks in '67-72 C-10s use the front two of the three factory holes in the top of the framerail. |