Rebuilding an LM7 GM Gen III 5.3

[redhat]

I picked up a Gen III 5.3 from a guy on Craigslist for $80. I am planning on putting an LS in my Regal. After tearing the motor down, I am finding out I'm probably going to need a full rebuild. I've got no problem with this.

A friend of mine is selling me a 6.0 crank. Used but in a awesome shape. Cylinder walls look good. I am planning on getting the block hot tanked and line honed. The rods are scored and the bearing are siezed to the crank.

I am under the impression that one of the 5.3s had forged Pistons from the factory. Is this correct? Anyone know which one? I was told the LMF?

Planning on a Holley HP system, LS6 intake, maybe some 799 or 241/243 heads? Not sure on cam yet. Maybe even some trick flow heads if something sweet comes up.

 

[Kruse]

After pricing machine costs, you might also want to consider starting with a brand new block. I'm pretty sure I saw Summit selling brand new 5.3 blocks for $299.

 

[EvanD]

I would use these
http://www.briantooleyracing.com/wiseco-...ns-k0044xs.html

Go for as high of a compression you can under 12

call cam motion and let them know your set up for a spec cam.

Consider trans and gearing now. Helps spec a cam. I would jump on 4.10's and small stall with matching cam.

Carbs are simpler than efi and would keep cost down.

 

[redhat]

Stock rods you think?

 

[EvanD]

I would not bother unless your getting a big cam or forced induction.

 

[RoadRaceJosh]

If you change the stroke you must have straight cylinder walls. This means a bore and hone. If you change the piston ring position in other ways so that the rings travel higher in the bore this is also true.

 

[dailydriver]

Originally Posted By: Kruse
After pricing machine costs, you might also want to consider starting with a brand new block. I'm pretty sure I saw Summit selling brand new 5.3 blocks for $299.


I believe that these were only the IRON 4.8 blocks which were production over runs from GM.

redhat; is that 5.3 alloy or iron??

 

[53' Stude]

I believe my brother informed me that the 5.3 engine has cast not forged Pistons. He rebuilds lots of them for people with GTO's and Camaro's

 

[clinebarger]

All (Ay least N/A) LS engines have hypereutectic pistons.

6.0L & 5.3L engine have the same stroke (3.622"), But you cant just throw a 6.0L crank in a 5.3L.....The rotating assembly will need to be balanced!!!!

In my opinion, Your putting too much money & effort into a Small Bore engine. This is coming from someone who owns a 5.3L....However I would never rebuild it, In fact a 6.0L will replace the 5.3L soon.

Eat the $80 & start with a 6.0L.....You can thank me later.

 

[clinebarger]

Originally Posted By: dailydriver
Originally Posted By: Kruse
After pricing machine costs, you might also want to consider starting with a brand new block. I'm pretty sure I saw Summit selling brand new 5.3 blocks for $299.


I believe that these were only the IRON 4.8 blocks which were production over runs from GM.

redhat; is that 5.3 alloy or iron??


4.8L & 5.3L block are identical.

 

[dailydriver]

Originally Posted By: clinebarger
Originally Posted By: dailydriver
Originally Posted By: Kruse
After pricing machine costs, you might also want to consider starting with a brand new block. I'm pretty sure I saw Summit selling brand new 5.3 blocks for $299.


I believe that these were only the IRON 4.8 blocks which were production over runs from GM.

redhat; is that 5.3 alloy or iron??



4.8L & 5.3L block are identical.


OK, but weren't they available in BOTH iron AND alloy versions??

 

[turtlevette]

Super Chevy did an article years ago on making junkyard 4.8 and 5.3s make 500 HP. All it took was head porting and an aggressive cam. They made power all the way up to 7000 rpm with the stock rotating assembly.

 

[splinter]

That $80 LS sounds like no bargain imho. They're plentiful and inexpensive...hold out for a 'good' one.

Some recommended reading if you haven't already:

GM LS-Series Engines / The Complete Swap Manual -Joseph Potak
How to Build and Modify GM LS-Series Engines -Joseph Potak
Building the Chevy LS Engine -MIke Mavrigian
How to Build Chevy LS1/LS6 V-8s -Will Handzel
Chevy LS Engine Buildups -HP Books

Each has its place in my reference library.

Parts interchangeability between various architecture, displacements, models (Gen-III and Gen-IV) and chassis fitment iterations takes some research.
Might find an OE oil pan that will swap straight into your A-Body. Good luck!