gsjimmy

Have a chance to pick up a '99 LM7 5.3, what are the downsides to this earlier model engine. It will eventually find its way into an '03 S-10 w/4L60 trans.

This will mean a shaved intake, DBW (using the S-10 cables) and 98/99 Camaro exhaust manifolds. Already have a scooped hood for clearance. After market oil pan, Corvette coil covers, relocated rear coil packs, notched frame for the A/C.

Need to know what I have not thought out on this swap.

What crossover pipe do I use/mod for this swap? Already know about the PS pump pulley.

Goal is a weekend swap, so the harness needs to be "done" prior to the swap. I do know that the factory tach will be off by 33% until I can fix it.

Thoughts?

Jim
2003 ZQ8 S-10

Currently finishing up a '76 Vega, 350 SBB/TH350, 3.42 posi

Mercier

iTrader: (15)

The early truck intakes and injectors should be replaced in most performance applications. The early trucks have return-style rails with a real regulator. The stock cam is about the smallest of the LS series. Some of the heads were known for cracking(706s maybe?). 862s are solid. Probably more but the gen-III 5.3s were basically the same.

gsjimmy

Thanks. Looking to do a "stock" type build, so a small cam is going to be OK with me. Need to do a DBC with the S-10, as it is already there with the 4.3 engine.

I believe that the fuel system that is currently in place is a return system for the S series trucks. Input on this would be great. Also am assuming that the in tank fuel pump is sufficient for a stock 5.3 (55-59 lb if I remember correctly). Again, let me know if this is wrong.

I'll stop by and look at the engine again tonight after work. Get the head numbers and anything else I see.

Since piston "slap" is common on the early engines, will a .020 overbore take care of this issue. I do have a competent machinist. Otherwise, maybe a re-ring/new bearing set if this is something to live with.

Now if I can find a set of good used 5.7 LS1 pistons.......

Next would be what computer to grab. Going with an aftermarket harness or used set-up here (GM, not MSD). This should take care of the reflash issue, and the complete harness. Trying to do this swap in a long weekend after X-mas. So parts gathering at this time.

The only other thing I am thinking is if the Flexplate is specific on a '99 5.3 in regard to distance.

Thanks, Jim

Mercier

iTrader: (15)

99 5.3 should be DBC. How many miles on motor? If 150K-ish or less, I'd run it another 100K. The LS really lasts if maintained. If a little cold startup noise bugs you then bore if you must but usually people either do a top end cleaning or live with it.

For your other questions, I advise you post in the "conversions and hybrids" section where you will find plenty of folks already finished with this exact swap.

Good luck with you build.

gsjimmy

OK, verified that it is a '99 5.3 last night. Code is XJB. It is missing the front drive accessories and will need a good cleaning (rings & bearings) and a paint job. Sitting under a tarp right now, but the price is $100. Been looking at drop outs with 100-130K miles, price has been running around 800-900 with a harness/computer. I'd guess that is where I'd be after freshening this one up.

The V8 S10 forum has a great section on the "How to install" an LS based engine into an S Series truck/blazer.

Looks like I'll be in the market for a set of used LS1 coil packs soon!

Mercier

iTrader: (15)

Nice. Glad you found what you need. Good luck with your project.

LS coil packs are usually available at junk yards pretty cheap.

gsjimmy

Tore down the engine last week to verify what I have. Very clean inside, and out. The little bit of water left a deposit on the 1 cylinder wall, and it cleaned up real nice with a hand hone and some ATF. Engine spins freely by hand. No ridge on the cylinders at all, end play is good.

Still need to disassemble the heads and clean them up.

Since this is going into a truck, should I focus on getting it up & running, or do the car coil packs and Corvette covers prior? I believe this matters to the building of the harness, end connections.

Jim