How to Know if You Got L33 or Lm7

Hi guys,

In this week'due south article, I'thou going to show you how to tell the difference between a Gen 3 and a Gen 4 LS engine. Every bit usual, I'thou going to be focusing mainly on the 4.8, 5.three and 6.0L LS-based Vortec truck engines since they are the most common ones y'all'll find when you're hunting through a junkyard. If you do discover a car LS engine, it's probably going to be expensive.

I'll be doing a more detailed commodity adjacent week about the evolution of the Vortec truck engines but figured information technology would be worth doing a quick one on how to tell a Gen iii from a Gen four. The next one will encompass more than information about specific models.

If the engine is still in the vehicle, the easiest way to identify the engine is using the eighth digit of the VIN. Here'south a photo of the VIN sticker found on the driver's door of my 2000 Chevy Silverado 1500.

The 8th digit of the VIN is "T." (Circled in red in the attached photo.) From the tabular array below, nosotros can tell that this is a Gen three, 5.3L, LM7 engine.

Here'due south a similar table for Gen 4 truck engines.

If you don't accept the VIN, if, for example, you detect an engine sitting on a pallet at the junkyard, here some ways you lot can visually tell a Gen iii from a Gen 4 engine.

Offset of all, if it has a throttle cable attached to the throttle trunk, similar my truck does in the attached picture, information technology is a Gen 3. Yet, the opposite isn't necessarily true. Merely because an engine has a drive-by-wire throttle body (no throttle cable), it doesn't mean that information technology'southward a Gen 4. Some Gen 3's had drive-by-wire, but no Gen 4'due south were drive-by-cablevision.

Another way to tell is by looking at the timing cover on the front of the engine. This information comes from Summit Racing, and they have a handy tool for identifying these engines, here's a link to their tool. The following images were taken from this link.

https://assistance.summitracing.com/app/answers/detail/a_id/4891/~/i-dont-know-the-vin.-which-ls-engine-practise-i-have%3F

If the timing embrace is plain with no blackness pickups on the forepart of it, the engine is a Gen 3. See attached photograph. If it has at to the lowest degree one pickup on the timing cover, information technology's a Gen four engine.

Adjacent, you can look at the intake manifold. If the manifold is low, smooth, and rounded, it is a machine engine, so if information technology'south a Gen 3, information technology will be an LS1 or LS6 engine. If the manifold is taller and boxier, has ribs on the top, or nonetheless has the "Vortec" plastic embrace on it, it'south a truck engine. See the photo below.

The adjacent thing to check is whether the cake is atomic number 26 or aluminum. An easy style to bank check this is with a magnet. A magnet will stick to an iron cake but won't stick to an aluminum block. You should also note the displacement markings cast onto the cake. These will be found on the front end of the engine, underneath the driver's side cylinder head, to the correct of the water pump, equally shown in the attached pictures.

If it'due south a Gen 3 engine, with an iron block, and a truck intake manifold, with a 4.8/5.iii stamped on the block, it'due south either a 4.8L LR4 engine or a 5.3L LM7 or L59 engine. In that location'due south no easy manner to tell visually from the outside of the engine whether information technology'due south a 4.viii or 5.3L. If you accept a borescope or pull a cylinder caput, the 4.eight commonly has flat-topped pistons and the 5.3 usually has dished pistons only there's no style to see that from the outside.

If it's a Gen 3 with an atomic number 26 block and a truck intake manifold and has 6.0 stamped on the cake, it's an LQ4 or LQ9 6.0L engine.

If it's a Gen 3 aluminum block engine with a truck manifold, information technology's a v.3L LM4 or L33 engine.

Another identifying characteristic that was pointed out by Kent Dalton for the vi.0L is that the Gen iv 6.0L engines have 13mm valley cover bolts while the Gen 3 has 10mm valley cover bolts. See attached photograph.

If information technology'south a Gen four, there are a lot more options as to what model it could be, some of them have AFM/DOD, some accept variable valve timing, etc but we'll cover that more than in the adjacent article, merely for now, this one should help y'all be able to place whether you're looking at a Gen 3 or a Gen 4 LS truck engine.

Next time, we'll go into more detail nigh the evolution of the LS-based Vortec truck engines. We'll cover the post-obit topics:

• which ones came with bulldoze by cable throttle bodies
• which ones came with bulldoze by wire throttle bodies
• which ones had 24x reluctor wheels
• which ones had 58x reluctor wheels
• which ones had flex-fuel
• which ones had active fuel management/displacement on demand
• which ones accept variable valve timing
• the deviation betwixt AFM/DOD and VVT
• which ones used return way fuel systems and which ones were returnless
• which ones had iron blocks
• which ones had aluminum blocks
• which cylinder heads came on each engine
• which cylinder heads are most desirable, and which ones to stay away from
• aid you lot choose a suitable donor for your LS swap or LS turbo project, and which ones to avoid.

That's all for this week, see you side by side time.

Randy (Lowbuck LS)

knapploortambel.blogspot.com

Source: https://lowbuckls.com/junkyard-ls-tech-how-to-tell-a-gen-3-from-a-gen-4-ls-engine/

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