Project LSZ: Changing a Chevy LS Reluctor Wheel at Home

Ever get fairly far along in a project, only to realize you totally did the first step wrong?

Yep, that’s where we were at with our LS-Swapped Nissan 350Z Project. When we built the bottom end of our engine, we didn’t know what we’d be installing it in. We also didn’t know what engine management system we’d be using. So, when we ordered our rebuild parts, we decided to keep things simple: We stuck with our early LS1 block’s original sensors, including its 24-tooth reluctor ring. This tone ring sits on the crankshaft and tells the crank angle sensor where the crankshaft is in its rotation. Our engine is what’s called a Gen III LS, and used a Gen III ECU and wiring harness from the factory.

Then, we met LOJ Conversions. They make a plug-and-play kit to put a Chevy LS into a Nissan 350Z, so we bought the car and decided that’s what we would use. But there was a catch: In order for us to use the plug-and-play wiring harness, we’d need a Gen IV LS. That’s one generation newer engine, and uses a better engine management system and sensor package. In order to put our engine into the 350Z with one of LOJ’s kits, we’d need to throw away the engine we’d been painstakingly rebuilding for over a year (hey, we do have real jobs, too) and start over.

Or, we could convert our Gen III engine to a Gen IV electronics package. The hardest part of that is the reluctor ring, which has 24 teeth on early engines like ours, and 58 teeth in the next generation. Rather than order another new crank, we decided to attempt replacing it at home instead. All it took was a special tool and an oven, at least according to the internet. How hard could it be?

First, we ordered the correct reluctor wheel and a reluctor wheel installation tool from Goodson. The special tool is critical to index and align the reluctor on the crankshaft, and we paid $219. After using it once, we sold it to a friend for $110, meaning our total investment was just over $100. Ask around, and you may even find a builder willing to loan you theirs. We also disassembled our engine again, as the crank needs to be out of the block for this operation. Once we had everything ready, we went to work.

First step: preheat the oven. GM reluctor wheels are an interference fit on the crankshaft, and are designed to be installed hot. We baked our reluctor wheel at 450 degrees for about an hour, expanding the metal and allowing it to fit over our crank. While it was cooking, we used a torch to gently heat the old reluctor wheel, then hammered it off. After letting the crank cool back down to room temperature, we borrowed our fiancee’s oven mitts, grabbed the 450-degree wheel out of the oven, and ran out to the shop. We set it up in the special tool, pushed it down onto the crank… and it worked perfectly. No drama, no fuss, just like a robot at the Chevy factory.

Our Gen III LS1 now had a proper Gen IV 58-tooth reluctor wheel. And we learned a lesson: before you build an engine, always think through the rest of the project. This was a day’s worth of work and $109 that we should have never wasted.

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