The LM7 is a 5.3L, Gen. 3 small block engine used in GM trucks between 1999 and 2007. For marketing purposes, it was also known as the Vortec 5300. The information listed here is for the stock LM7 engine.
Mechanically similar, General Motors’ LS and LS-based Vortec engines wound up on almost every branch of the GM family tree: Chevy, Pontiac, GMC, Cadillac, Buick—heck, even Saab, Hummer, and Isuzu got some LS love.
Since LS and Vortec engines are so common, they’ve become the go-to performance and swap engines of the modern era.
These motors are capable of making a lot of horsepower, and respond well to upgrades like turbos, superchargers, high-flow cylinder heads, intake systems, cams, and nitrous oxide.
The aftermarket is strong, crate engines are available, and used motors are often cheaply sourced through junkyards.
[Trying to find an LS engine? Check out Part 1 and Part 2 of our LS Spotter’s Guide.]
Summit Racing has created a series of comprehensive guides for each engine in the LS family, so engine builders and tuners can have a handy reference for their projects.
This specific guide is for the Chevy LM7 LS truck engine.
(Summit Racing’s Paul Spurlock and Brian Nutter contributed to this article.)
GM LM7 Engine Specs
|LM7 Engine Ratings|
|Horsepower Rating||270-295 hp|
|Torque Rating||315-335 ft.-lbs.|
|VIN 8th Digit||Year||Make||Model|
|T||1999-2006||GMC||Yukon XL 1500|
|LM7 Block Specs|
|Casting Numbers||12567392, 12567393, 12551358|
|Displacement||5.3L / 325 c.i.d.|
|Bore Dia.||3.780 in.|
|Deck Height||9.230-9.240 in.|
|Bore Spacing||4.400 in.|
|Thrust Bearing Location||#3 Main|
|Main Cap Style||6-Bolt|
|Main Housing Bore Dia.||2.751 in.|
|Cam Housing Bore Dia. (1999-2003)||Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307|
|Cam Housing Bore Dia. (2003-07)||Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307|
|Cam-to-Crank Centerline||4.914 in.|
|LM7 Rotating Assembly Specs|
|Piston Material||Hypereutectic Cast Aluminum Alloy|
|Wrist Pin Dia. (1999-2004)||0.9447 in., 0.9448 in. (Pressed)|
|Wrist Pin Dia. (2005-07)||0.9429 in., 0.9431 in (Floating)|
|Connecting Rod Material||Powdered Metal|
|Connecting Rod Style||I-Beam|
|Connecting Rod Length||6.098 in.|
|Connecting Rod Bolts||M9 x 1 x 43|
|Crankshaft Material||Cast Iron|
|Crankshaft Main Journal Dia.||2.559 in.|
|Crankshaft Rod Journal Dia.||2.100 in.|
|Flexplate Mounting Flange||0.857 in.
|LM7 Cylinder Head Specs|
|Casting Numbers||862, 706|
|Combustion Chamber Volume||61cc|
|Intake Port Shape||Cathedral|
|Intake Runner Volume||200cc|
|Exhaust Port Shape||Oval|
|Exhaust Runner Volume||70cc|
|Intake Valve Diameter||1.890 in.|
|Exhaust Valve Diameter||1.550 in.|
|Cylinder Head Bolt Style||Torque to Yield (TTY)|
|Cylinder Head Bolt Size (1999-2003)||(8) M11 x 2 x 155, (2) M11 x 2 x 100, (5) M8 x 1.25 x 45|
|Cylinder Head Bolt Size (2004-06)||(10) M11 x 2 x 100, (5) M8 x 1.25 x 45|
|LM7 Camshaft Specs|
|Duration @ .050 in. (int./exh.)||191°/190°||191°/190°|
|Valve Lift (int./exh.)||0.457 in./0.466 in.||0.457 in./0.466 in.|
|Lobe Separation Angle||115.5°||114°|
|Cam Gear Attachment||3-Bolt||3-Bolt|
|LM7 Valvetrain Specs|
|Lifter Style||Hydraulic Roller|
|Lifter Link Style||Plastic Lifter Tray|
|Lifter Body Diameter||0.842 in.|
|Pushrod Length||7.385 in.|
|Rocker Arm Mounting Style||Pedestal|
|Rocker Arm Style||Die-Cast, Roller Fulcrum|
|Valve Spring Style||Beehive|
|Valve Spring Color||Natural|
|Valve Angle||15 Degrees|
|Intake Valve Material||Steel, Solid Stem
|Intake Valve Dia.||1.890 in.|
|Exhaust Valve Material||Steel, Solid Stem|
|Exhaust Valve Dia.||1.550 in.|
|LM7 Throttle Body, Fuel Injector Specs & More|
|Intake Manifold||Truck Style|
|Throttle Body||78mm, 3-Bolt|
|Throttle Control (1999-2002)||Throttle Cable|
|Throttle Control (2003-04)||Electronic, Drive-by-Wire (most models)|
|Fuel Injector Flow (1999)||21.8 lbs./hr.|
|Fuel Injector Flow (2000)||24.8 lbs./hr.|
|Fuel Injector Flow (2001-07)||25.2 lbs./hr.|
|Fuel Injector Length Between O-Rings||1.9 in.|
|Fuel Injector Connector||Mini-Delphi / Multec2|
|Crankshaft Reluctor Ring||24x|
|Camshaft Sensor Location||Rear Mount, 1x on cam|
|Oil Pan||Deep Rear Sump|
|Oil Pump||Standard Volume|
NOTE: You can find engine specs and detailed engine upgrade advice for every LS and LS-based Vortec truck engine in one place: The Definitive Guide to LS Engine Specs and LS Engine Upgrades.
[…] LM7 5.3L Vortec 5300 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & M… […]
I have a 2003 vortec with 2 different casting numbers, behind top intake on block it has 12559767 on rear of block behind fly wheel is 12551358 with 862 heads. Mexican build gm plant motor, which is it , 4.8 or 5.3
[…] It’s is very similar to the LM7, except that it’s built on an aluminum block, and the LM7 is an iron-block engine. […]
just want to know what my 2003 lm7 5.3 1500 ls truck horsepower rating is. I think it is 285hp ?
It really depends on your specific vehicle application–but your 285 estimate is certainly right in the ballpark. Our table above says, depending on the vehicle, it’s between 270 and 295 hp.
I Getafe the same model truck, and the owner manual said 285 hp
Ya, but is this to the rear wheel hp or to the crank?
I am doing a cam delete plate moving the cam sensor to the front and putting in a custom cut zo6 cam with a single bolt cam gear. Unfortunately I ported and polished the 706 cast heads before I learned of their suseptability for cracking. so now i have to re do the 50 hours of hand to head work on the set of 862s i collected. My inquirey has a feew parts to it. 1; will the cam gear mate up with the crank as I want it to with conventional instalation? Ive heard that the two have different amounts of teeth and have been told I need to change the crank. Fingers crossed that I dont. 2; im putting this back into an 02 avalanche. Is it gonna start or will I have to have the ECU reprogramed? 3; Will I need to obtain a stall torque converter, and finally 4;Ive come across a set of H beam rods but there only 6 inch. Will a set of 4.8 flat top pistons make up the difference in lost compression? Any other advice or suggestions are welcome. To be in the know, Ive upgraded the trunions, added a hi flow oil pump, added 3/8 pushrods, added heavier valvesprings, and port matched all the gaskets.
Hi Casper, we’re not quite sure what engine type you’re starting with so we’ll address both.
If you have a Gen. 4 engine, nearly all of them came with 58x reluctors and won’t be compatible with the ECM in a 2002 Avalanche (24X reluctor ring). You are correct that you would need to swap the crank or reluctor itself.
If you have a gen. 4 intake and throttle body, be aware they aren’t wired like the Gen. 3s that were cable driven or used TAC module and different pedal assembly. You may need something like the Torquerush X-Link module to convert, but there’s a chance you could use a straight harness with a 90mm LS2 TB and have it be compatible with your 2002 ECM. Knock sensor extensions would also be required, but some leave them unhooked…which is a little dicey.
Now, Let’s talk about you starting with the LM7 or other Gen. 3 engine. The good news is you already have some pretty good stuff to work with. Definitely check out our LM7 upgrade article for some good tips. Most of the aftermarket cams out there are built on a 3-bolt core, so you can keep the top and bottom timing gears from what you have and just throw a stronger LS2 spec timing chain on it. The rear mount cam sensor is fine, so that saves you a bit of headache. Knock sensor locations too.
The ECM will start and run, but anytime you’re adding horsepower…you will want to have it tuned…there’s big power there anyway. The biggest injectors that came in LM7s came in the 2001-07 versions. At 25 lbs., they support about 380 hp (to the wheels) which may be enough depending on how big you go with the cam.
As for converters, the Stage 1 and Stage 2 Summit Racing Pro LS Truck cams will work with a stock converter. The stage 3 cam would like a 2,500 converter and the Stage 4 would like a 2,800 converter. You can check out those cam specs on the Summit Pro LS Cam article to get an idea of the duration numbers etc. for comparison.
The 6 inch rods you found are probably made for gen. 1 or 2 small block Chevy. The problem is they have an offset in the beam that makes them un-centered under the piston…this causes side loading. Gen. 3/4/5 rods are on-center, so definitely stick with them or aftermarket.
Lastly, flat tops would not help enough to recover the compression of having a piston .100 in. farther down in the cylinder with a short rod.
The 1999-04 LM7 rods used a press fit .9449″ pin vs. the 2005-07 models which switched to the beefier Gen. 4 rods and .9431″ full floating pins. If you aren’t running over a 150 shot of nitrous, one possible combination includes these Scat connecting rods. These are press-fit, stock length rods that would be compatible with Keith Black UEM-2482HC-5MM ( .010 in. overbore) flat top pistons with .9449″ pins. That would get you up to 10.7:1 with the 61cc chambers on the LM7 heads. If you are making more power, then the aftermarket rods are 6.125″ long and have a .927″ pin usually. There are lots of forged pistons available and a flat top version with 2 valve reliefs is pretty easy to find.
The rest of your combination sounds pretty good, but the 3/8″ pushrods are going to require clearancing on the outside of the intake runner. Commonly available .080″ wall 5/16″ like these from Summit Racing are a good choice. Hopefully the information above helps. If we didn’t answer everything, give the folks at Summit Racing a call (330-630-0240) and they can guide you through the process.
I have a stock 5.3L in a 2002 Silverado truck. It has 200,000 on it and I want to build a replacement engine for it. I have built several small blocks over the years but never an LS. I fell in love with this LS and want to build one for this truck with more horsepower but keep it for daily driving. What is your recommendation for Crank, cam, intakes, pistons, rods, and whether to start with a 5.3L or 6.0L ?? I would like to have 350-400 hp.
Mike, find a 6.0 and rebuild it to your needs, there’s no replacement for displacement as the saying goes.
I have a 2000 chev silverado 5.3L 200K miles.
Looking for best replacement engine.
Any legal cam change for better performance?
Any other recommendations?
[…] workhorses like the Chevrolet Express Van, Silverado, Tahoe, Suburban and that weird Avalanche. OnAllCylinders.com did a nice run-through of what this engine […]
[…] LR4 was introduced in 1999. Along with the LM7 and LQ4, they were the first LS truck engines. The LR4 was available in GM pickups, vans, and SUVs […]
2002 suburban 5.3 292000 no issues other than knock sensors my question is how big of a lift and duration cam can I go without having to change anything other than the cam and lifters
Can this engine hold a 6.0 transmission. My transmission is going out and my uncle has a 6.0 transmission from a 98 version of my 2000 suburban truck
How much boost can the LM7 take?
I’m running 15 psi boost on A stock Ls7 motor and have run 65 quarters with it. Low octane of course.. But..I am losing some antifreeze out the tail pipes now tho!!! Most likely head gasket.
Can I use my stock pedal if the throttle body is cable or does the ecm still look for pedal position? I have a 95 2 door tahoe
I have a 200q gmc sierra 1500 5.3L 2wd and my rear end went out on me. I want to go with a beefier rear end and would like to know what specs I should go by, I’m trying to get more torque out of it instead of speed
I did used a dial indicator on a stock cam and came up with 0.270″ lift and I’ve bin reading and it should have 0.457″ intake lobe what cams did get used this makes no sense
The cam lift is just that, lift at the cam lobe. You have to multiply the cam lift by the rocker arm and then you’ll have the actual lift of the valve from it’s seat.
A quick run down is say you have .320 lift on the cam lift, and your rocker arm ratio is 1.5. Multiply the lift times ratio like this: .320 X 1.5 = .480 lift from the valve seat.
I hope this helps clear up the lift question you had.
I have a 2005 gmc sierra. I am trying to convert my Gen 3 block to an aluminum Gen 4 block. I have purchased the block.
Here are my questions….
1) I understand I have to relocate the knock sensors. From my valley to the side of the block. Is there a place already there that they won go in? I have read that is a no. Where do I put them?
2) the valley cover has the DOD stuff on the gen 4, and mine does not. When I relocate the knock sensors, what do I do about the 2 large holes in the valley cover?
3) gen 4 cam sensor is in the front timing cover where as mine is in the top of the valley cover? What do I do about the hole in the block if I move mine to the front where the gen 4 is, and what do I have to do in order to make this work with the cam from gen 3?
4) I am putting a 24x crank in this 58x motor….. I assume this will be fine? I’m not changing the wheel, but the whole crank.
5) is there anything else I need to be aware of with this swap????
Thank you so much in advance for the help.,
I am trying to find out if I have a DoD engine. I need to do a lifter job. I have been told that if is is DoD I will have to remove the heads to do this.
I just pulled the info from the SILVERADOSIERRA.com forum:
The active fuel management I believe has the DOD as part of it or is it.
2007+ New body style 5.3L engines have AFM. The 6.2L engine thru the 2013 model year was not AFM in the 1500 trucks. The 6.2L in the SUV did have AFM though.
Do some more checking on the forums or go directly to GM and they’ll have all the info you need without any questions on the veracity of it.
[…] past updates we freshened up this LM7 V8 by installing a mix of quality replacement parts and Summit Racing’s Pro LS Series high […]
What is the cylinder bore angle is it the same as a gen 1 or gen 2 block can it be bored with the same tooling as the old blocks
And what is the head and valve angle on the ls motorsv?
Will a 6.0 engine from a 2005 hummer h2 fit into a 2002 avalanche 1500? If so does the tranny need to be changed out with the engine?
Aonde consigo a bomba da direcao hidraulica para ser enviada para o Brasil
Olá! A Summit Racing embarca para o Brasil, clique aqui para saber mais.
does a 2003 chevy silverdo 1500 4×4 truck with 5.3 engine have a egr valve? My truck idles rough after I googled the problem it points to a egr valve so I went to Auto Zone the gentleman looks in the book and said there is a gasket but shows no egr valve. Being a Sunday all the mechanic shops are closed and you help me? Thanks
I purchased a 383 stroker from Summit, it is a 1996 chev block. I am wandering if I can use the vortec heads, intake and all the rest of it to put on it so I can install it in my 2009 chev silverado 4×4?
That’s the wrong engine for that truck. The truck uses a Gen IV LS type engine, and you bought a Gen I small block. Nothing interchanges between them. Sell it and buy an LS Vortec engine.
Could this motor be swapped with a 6.0 liter L76 motor? I am trying to get a 2007 chevy Silverado duramax running and I don’t know how to find information on transmission bolt patterns or motor compatibility. It says that the 6.0 liter has a computer of E38 but I don’t see a computer on this motor so does that mean it would not work.
What is the valve stem diameter of the stock lm7 valves?
Hi. Great web site thanks. Can i put any 5.3L in any 5.3L ?as the list shows 99 to 2006. Suburbans.
Without new harness and computer adjusting.
(2000 Suburban LT 5.3 1500 to 2004 or 2006 sub )
I have an ‘03 Avalanche with the original 5.3. My question is this, and I hope simple. I am planning to do a mild rebuild of the 5.3. Cam, thermostat, tune, and possibly under drive pulleys…is it worth the expense, for what I see as minimal gains, to upgrade the intake to the TBSS and all that would entail?
[…] on a smaller 5.3L. In fact, we broke the 500-horsepower mark with that cam on the little LM7, so we naturally had high hopes for the larger […]
[…] [Every engine spec you’ll need can be found here: LM7 5.3L Vortec 5300 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & M….] […]
[…] It’s is very similar to the LM7, except that it’s built on an aluminum block, and the LM7 is an iron-block engine. […]
[…] It was known as the Vortec 5300 and made a little less power than its aluminum-block brother, the L33. This was due to the LM4’s smaller intake valve Cathedral port heads, lower compression, and a slightly smaller cam. With the exception of the block material, it had more in common with the iron-block LM7. […]
[…] The L59 engine is a 5.3L Gen. III iron-block engine used in GM trucks and SUVs between 2002 and 2007. It is essentially the flex-fuel version of the LM7. […]
[…] L59 (along with the LM7) is a Gen. III, 5.3L iron block truck engine you can pick up in wrecking yards for about $600. The […]
my yukon has got a few miles on it but to be fair im 3rd owner and actually knew the 2nd owners and know the engine has been kept serviced and driven moderetly at the harshest word to use to describe its use.i want to up the performance of the vehicle and not go wild with just add a few horsepower and go pretty good if neede to do that Im a rookie with some basic knowlege of mechanicin on my car.all i really want to do is swap out the camshaft and get that good throaty lick and know somethin is in ole gramps big ole 4×4 yukon. honestly need to know what to do first out of the chute.
Just getting started in the Ls world have a 5/3 swap in 74 nova i no they make power would like to do cam swap but realy thinking about a single turbo set up.whst cam can i use to make good sound an power now but work good when i make the leap into turbo. That way im not nacking up
How much HP can a LM7 handle?
LM7 5.3 can handle about 750 hp but after that you need performance parts. after 750 the pistons and rods can get dicey. if you do it right and get all the right parts an LM7 can handle over 1,000hp
so then in regaurds to that 1000 hp conversation about the lm7 a 3rd gen 5.3 is good for 750 stockish prepapred and 1000 with what crank rods and pistons from the aftermarket, or can you offer some knowledge that i can put to use in my current experiment? i already have a turbo setup a clean std bore block that was in a running truck elgin 1841p cam pac1218 springs/btr66o’s also and a couple sets of heads but im looking for a reason to call up the fellas at trick flow i want the 255x’s.
Looking for a 3rd gen lm7 engine with wiring harness with around 80k miles. Need pricing and availability please
Very hard to find in n.c. Check Tennessee lots rusted cars there
With the Brain Tollie cam truck noris need injectors or any other up grades to get it to work.
I have a 2005 chevy silverado 5.3l iron block w/862 aluminum cathedral heads. I want to upgrade the intake and I came across a 2010 5.3l cathedral intake manifold complete. Only thing is it has flex fuel injectors. My question is can I install this intake on mine? If I need parts to install it could you list what’s needed i appreciate it.
I have a 1999 5.3 Ls(LM7) that I got for $200 I want to turn it in to a 363 stroker. I’ve found a rotating assembly for it on CNC Motorsports… is there any way you would be able to tell me wat would I need to bore the block to nd no im not trying to get a motor bc I’m using this 1 for a project motor not worried about spending