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Join Date: Jul 2008
Maaso is offline
Re: L31 (5.7 Vortec) in 2001 S10 4.3
Do a search for my name, I have an a very detailed build thread somewhere on swapping an L31 into a four-by. But to answer your specific questions...
1: Yes, the original harness will "plug-in-play" into the L31, but you will need to add a few wires to the injector pod and repin the wires going into the PCM to accommodate the change in firing order. Depending on some trucks you may need to extend the lead for the AC compressor and the knock sensor. I relocated my knock sensor to the driver's side because I was worried about heat soak from my custom headers on my truck, the amount (and if an extension is even needed?) will vary from truck-to-truck
2. If you are running stock Vortec heads, the max lift is roughly .475 and will vary depending on who you talk to. Some say it's .450 and others will say it's .490 and anywhere in between. The only way to tell is to measure spring bind on YOUR SPECIFIC heads. And if you need more lift, you can call up Scoggin Dicky and spent ~$30 on some "Z28" springs that will drop onto the Vortech heads with absolutely no modifications or expensive machining and will net you ~.525 lift. The LT4 cam is a decent cam, but I've heard from a few tuners that its difficult to tune. Check with your tuner first and ask for a cam recommendation for your particular setup. And if you are planning to run the simple stock EFI, the only intake option is the stock intake. If you want to spend some money and do some custom plumbing/wiring then any "Vortec" intake will bolt up.
3. You can use either the 4.3 or 2.8 mounts. I have(had) a 4x4 that has 4.3 mounts integrated into the frame. But from what I've read you have a 2wd truck. Which means you can swap out your mounts. If you run the 2.8 frame mounts then you can use the JTR mounts that allows the engine to sit ~1 inch lower than stock. If you reuse the 4.3 mounts then you can use the Advanced Adapters "plate" mounts that raises the engine ~1/2 inch which can - and will - interfere with any some headers since the steering shaft runs through them. Since you have a 2wd, I would highly running Hooker's mounts that allow the use of real V8 clamshell type mounts. These will clear up tons of room for any header option and wont require relocation the knock sensor.
4. As S15vortecpwr said, the 4.3 converter has a higher advertised stall than the 5.7 converter. The 4.3 converter is actually a physically smaller converter with a higher fin count, which will make the 4.3 converter "stall" higher with the 5.7's increased torque. The 4.3 tranny will bolt up the the 5.7 with zero modifications. You may need a different dust cover depending on if you have a 4x4 or a 2wd.
5. I would highly recommend you get rid of the blocks and use a shackle/hanger lowering kit. Blocks act as "levers" and increase leverage on the leaf springs that induce crazy amounts of spring wrap. The amount of fan/radiator clearance will depend on the mounts you use. The JTR/Advance Adapter's mounts give you roughly 1/2 inch either forward or behind the stock position. The Hooker mounts will place the motor in the stock position with almost no adjustment. Running the JTR/AA mounts may require you to notch the bracing in the hood to clear the AC compressor.
I've done many first gen V8 swaps, and one 2nd GEN 4x4 swap, so if you have any questions feel free to PM me. Since I sold my truck I don't get on the site much anymore. And sending me a PM is linked with my email, so I'll get it even if I'm not logged in.
Current owner: '99 ZR2, 383 Vortec L31
Previous owner: '93 GMC Typhoon #2025
Might still own: '88 GMC S15 with SBC, I don't know where it is now or who has the title.
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