**Need advice; Looking to buy this LS engine

[1972K20]

I'm not familiar with some of the LS "lingo." Here's the guy's ad. I'm going to see it, but are these mods ok? Anything here to be concerned with?


5.3 LM7, recently freshened and prepped for Boost application
-Can hear run on engine stand!!
-professionally reworked stock harness with fuse/relay block and 2 wire easy hookup
- unlocked and base tuned ECU included
-97-98 LS1 cam (probably 30hp upgrade over stock truck cam) (boost friendly)can include stock cam if you want it.
-new pac 1218 valve springs
-new pro-comp head studs (needed for boost applications)
-new valve seals, spark plugs, MLS Head gaskets
-heads cleaned and valves lapped
-includes truck intake and Fbody Oil pan/pickup/windage tray.
- brand new starter, all other accessories included. Has dirty dingo idle relocator to run car intake with truck accessories. Stock truck manifolds cleaned and painted with high temp paint.
- drive by cable throttle body
- oil pressure gauge can be included


Thanks guys!

[Aruba1]

Price? Shop or individual selling? Warranty?

[BR3W CITY]

Originally Posted by 1972K20

[I]5.3 LM7, recently freshened and prepped for Boost application
I want to know whats "prepped for boost" on this, aside from the head studs.

-professionally reworked stock harness with fuse/relay block and 2 wire easy hookup
Possible, but its usually at least 4 power wires...and we need to know what its reworked FOR. Which trans, truck or car ECM and harness?

- unlocked and base tuned ECU included
This almost never is as plug n play as it sounds. IMO I'd rather have a stock ECM and have it tuned per my requirements.

-new pro-comp head studs (needed for boost applications)
There were horror stories about Pro Comp head studs for a while. Not sure if they still have issues, but I will ALWAYS spend the money for ARP.
-new valve seals, spark plugs, MLS Head gaskets
-heads cleaned and valves lapped
Need more info on this. Were there any dimensional changes made to the head surface (milling etc).

I don't see much in that list that really screams "ready for boost". I also tend to think that "freshened" is a buzzword which substantiates very little. It seems like the block hasn't ever been opened, so that could be a 170k engine that blew a headgasket...owner threw some new gaskets and hardware in (since you have to anyway), and now calls it a fresh boost motor.

Unless he only wants $700, or can find a whole bunch more info, I wouldn't be handing over any cash.

[Aruba1]

Yes, agreed with the comments. Since the motor is on the stand, you may want to also check compression.

When I bought my motor the PO said it was in perfect condition. Got it put in the truck and it ran like crap. 150 PSI on cyl 1, 90 on cyl 3 and 0 on cyl 5 so the headgasket was gone. Took the heads off and I noticed excessive play in the pistons meaning new rings and rehoning of the block. With that I got thinking that the new higher compression to the motor would boil down to additional strain on the used bearings so I decided to do a complete rebuild. What I am trying to say is that you will never know what the engine needs until you go in there. If the rings have some wear you won't know until a couple thousand or 10 thousand miles. That is why I asked if this was a shop rebuilt and if you can get a warranty. But it will all depend on the asking price.

Just the re-ring kit for the 5.3L (bearings (cam, rod, crank), stock oil pump, full gasket kit, stock rings, stock head bolts, etc) cost a whooping $600. My heads were warped so I paid $150 to have them milled and reworked. Another $80 went into polishing of the crank and cleaning/checking the block. If you took it to a shop for a rebuild it would cost probably around $2k. My next LS engine will be one needing a rebuild, I will never again buy a drop-in engine again unless I can drive it around the block AND pull compression on it. Just by 2 cents.

[1972K20]

Thanks guys, sounds like I may pass. He's asking way more than $700. I thought it might be a good deal since I could hear it run. Since I've been looking for a LM7, I wanted one in stock form anyway.

[Aruba1]

I just stumbled across the ad on CL and the asking price of $1800 for a freshen up a bit too high, even when it comes with the harness and dingo mounts.

[MalibuSSwagon]

Originally Posted by Aruba1

Yes, agreed with the comments. Since the motor is on the stand, you may want to also check compression.

When I bought my motor the PO said it was in perfect condition. Got it put in the truck and it ran like crap. 150 PSI on cyl 1, 90 on cyl 3 and 0 on cyl 5 so the headgasket was gone. Took the heads off and I noticed excessive play in the pistons meaning new rings and rehoning of the block. With that I got thinking that the new higher compression to the motor would boil down to additional strain on the used bearings so I decided to do a complete rebuild. What I am trying to say is that you will never know what the engine needs until you go in there. If the rings have some wear you won't know until a couple thousand or 10 thousand miles. That is why I asked if this was a shop rebuilt and if you can get a warranty. But it will all depend on the asking price.

Just the re-ring kit for the 5.3L (bearings (cam, rod, crank), stock oil pump, full gasket kit, stock rings, stock head bolts, etc) cost a whooping $600. My heads were warped so I paid $150 to have them milled and reworked. Another $80 went into polishing of the crank and cleaning/checking the block. If you took it to a shop for a rebuild it would cost probably around $2k. My next LS engine will be one needing a rebuild, I will never again buy a drop-in engine again unless I can drive it around the block AND pull compression on it. Just by 2 cents.

This is why I buy running parts trucks to get my engines from. I spend on each truck what most people spend on just the engine, plus I can make my money back by parting the truck.

There was a guy on my local forums, he would boast about how he'd pick truck engines off the junk pile at his buddies salvage yard, then a week later he would list the long block on craigslist for top dollar all painted and pretty. I'm sorry but stainless button head bolts and flashy paint don't make a good engine.

[1972K20]

Originally Posted by MalibuSSwagon

This is why I buy running parts trucks to get my engines from. I spend on each truck what most people spend on just the engine, plus I can make my money back by parting the truck.

There was a guy on my local forums, he would boast about how he'd pick truck engines off the junk pile at his buddies salvage yard, then a week later he would list the long block on craigslist for top dollar all painted and pretty. I'm sorry but stainless button head bolts and flashy paint don't make a good engine.

^^^This is the way I've always planned on doing it and is really the best way.

[Aruba1]

1972K20, there is a vortec 454 in Pinson that the guy is asking $800 for and it's still in the truck. It's on CL, search for "vortech 454".

[1972K20]

Originally Posted by Aruba1

1972K20, there is a vortec 454 in Pinson that the guy is asking $800 for and it's still in the truck. It's on CL, search for "vortech 454".

Thanks, I'm looking for a LM7 right now. However, the 454 would be really cool.

[MalibuSSwagon]

It is the best way really, and up here in the north there is no shortage of rusty parts trucks. I mean I have two sitting in my yard right now awaiting their demise. I understand down south there is a much shorter supply of such trucks, and as a result prices are much higher.

[TooTall]

Originally Posted by 1972K20

I'm not familiar with some of the LS "lingo." Here's the guy's ad. I'm going to see it, but are these mods ok? Anything here to be concerned with?


5.3 LM7, recently freshened and prepped for Boost application
I slapped some shiny paint on the block, and I painted right over the dirt and grease
-Can hear run on engine stand!!
I want to prove to you that it starts and doesn't knock . . . but it looses oil pressure after 100* degrees
-professionally reworked stock harness with fuse/relay block and 2 wire easy hookup
I love using butt connectors
- unlocked and base tuned ECU included
I tuned out the VATs . . . vehicle anti theft.
-97-98 LS1 cam (probably 30hp upgrade over stock truck cam) (boost friendly)can include stock cam if you want it.
I took an old cam from a busted motor, I really have no idea what the cam is out of
-new pac 1218 valve springs
these are ok single beehive replacement springs
-new pro-comp head studs (needed for boost applications)
if they are ARP head studds, they're expensive, the stock TTY bolts are plenty. The china knock offs are really cheap
-new valve seals, spark plugs, MLS Head gaskets
MLS Multi Layer Head Gaskets
-heads cleaned and valves lapped
Cleaned the funk off the heads, makes them shiny, machined valves to be like new,. . . makes a better seal
-includes truck intake and Fbody Oil pan/pickup/windage tray.
Truck intake for better torque, Fbody pan more than likely came from a camaro, has more ground clearance.
- brand new starter, all other accessories included. Has dirty dingo idle relocator to run car intake with truck accessories. Stock truck manifolds cleaned and painted with high temp paint.
I painted the accessories to look pretty, the bracket was to be used for other low profile intakes. Painted manifolds just to look pretty.
- drive by cable throttle body
Cable throttle body, to be used on older cable style gas pedals
- oil pressure gauge can be included


Thanks guys!

I was a huge smart ass when I responded to a few things. This build looks like as if it was intended to be a low buck turbo build.
There's nothing mentioned about the timing chain, oil pump, pickup tube oring, and lifters.
Head studds are a band aid. The block needs to be machined for the extra torque that is placed on the cylinder walls. The extra torque will distort the cylinder wall, and it will not be completely straight or "true"
The PAC springs are a great replacement, but they can't take the abuse from larger lift and aggressive cams. Nothing to worry about with the small LS1 stock cam
The LS1 cam, . . . it is smaller spec wise to the truck cam. No benefit to having this over the original truck cam, if anything it's a step backwards. Will it hurt anything, . . . no.

The relocator bracket is so that you can run a lower profile intake with out it hitting the belt. No benefit on this setup as it sits.

The standalone harness might be nice. Just look for soldered connections, 40+ amp relays, (should be 2 at the least). Nothing heavy duty needed except for the fuel pump.

again, this sounds like a spare parts shop build.

[THEE OG]

5.3s are everywhere. One was local and the guy wanted 500$

What are your goals with the motor?

[e015475]

I've bought probably a half dozen LS motors out of junkyards over the last ten years with pretty good results.

Not a fan of buying a complete running wreck, pulling the motor and parting the rest out. For me storage is an issue, and the last thing I want is the aggravation of selling parts (and my wife asking me when that eyesore is going away). This is supposed to be a hobby, not a business, but rant over.

Everybody on Craigslist thinks the 5.3 they pulled out of their crapped-out truck before they took it to the scrapper is a 'LS1' and equivalent to a Corvette motor. Some are just like the ad you posted and get a turd out of a wreck or the pick-and -pull and do a rattle can overhaul and triple their money. Most don't even really know if they have a 5.3 or a 4.8 motor (check the 7th place on the VIN marked on the block's deck at the front of the motor - there should be a 'T')

Here's my suggestion on how to go about buying a used 5.3.

- Look in car-part.com for junkyards near you that have LM7s. If you want a drive by cable throttle, look for wrecks up to 2002. Most after this are drive by wire. I stay away from anything with more than 100K miles. Everyplace you stop, ask who else has 5.3L inventory they know about.

- Look for yards that still have the motor in the truck/SUV where you can look at the mileage and condition of the truck. Pull the valve covers - if it isn't clean on just a little golden brown inside - walk away. Make sure it has oil in it - a shattered cast pan in an accident is pretty common.

- Junk yards want to sell you a long block, then nickle and dime you to death with the accessories. Ask for the 'pull out' price with everything. Trying to piece an engine together with different PCM, throttle body, harness and crank reluctor ring is a PITA and expensive - buy it all out of the same vehicle. This is especially true if you're buying a drive by wire - make sure you get the pedal assembly, the TAC module and jumper harness all from the same vehicle with the engine.

-When they say the engine is warrantied for a year, ask for a price reduction if you don't take it. None of my projects ever were running a year after I bought the motor, but I can almost always negotiate some off when they write 'no warranty' on the invoice. The probability of ever collecting on a warranty at one of these places has got to be pretty close to zero.

-Offer cash. This works well at the mom and pop type yards, but not so much at the 'corporate' junkyards like LKQ. Cash flow is king in a small business and you can get a better deal most times with cash.

- Be prepared. Have cash on you, Have a truck with an empty bed and tie-down straps ready to pick up the motor.

Bring it home, run a compression test. If it looks good, keep the heads on it. Remember each time you pull the heads you have to buy a new set of head bolts and head gaskets to the tune of a couple hundred bucks. (or you can stud the heads for a few hundred bucks more, but please don't roll the dice with the Chinese studs)

Flip it over and pull the pan, check the condition of the rods and mains and if they look good put it back together. I like to put a new oil pump in them for insurance, along with a careful installation of the oring on the pick-up tube. Put the pickup tube and pan on of your choice for your installation.

I'd put a new rear main seal in it too for insurance. I like NAPAs seal that comes with a plastic tool you remove once you have the seal on the crank - it is slick. Replace the intake to head gasket - a common source of vacuum leaks.

The latest engine I bought was about a year ago. Mom and pop junkyard for cash. It was the aluminum 5.3L engine out of a Trailblazer (worth a little more than the iron block) 94K miles, $600 I wanted a drive by cable for my project so I bought the harness and throttle body from another truck, along with all the accessories for another $175 (I know I said not to do this) as a bundle with the motor. This was a little more than half his asking price when I walked in the door - and this is pretty typical.

Happy hunting - YMMV

[1972K20]

That's some solid advice right there. Thanks for taking time to share that. What are you looking for in the rods and main? Excessive wear?

I have a 72K5 that it will be going in.