T4nkz

Hey guys, I wanted to ask some novice questions. So I bought a 5.3 LM7 motor out of a trailblazer with 80k miles on it from a junkyard. I took the heads off and they looked clean, the motor turned over, and there’s no visible damage.

Should I still bring the motor to a machine shop to rebuild it?

Do I need to bring it to a machine shop to get it rebuilt if I plan on staying NA with a TSP stage 3 cam kit, new valves and retainers, oil pump, and 7.4 pushrods? Or could they just put those in the motor and resurface the head?

B52bombardier1

I'd not rebuild the motor and do exactly as you describe above. Just put your new parts in the motor and go with it as far as the mechanical build is concerned. With only 80,000 miles on the motor, it has perhaps 200,000 miles or more of life remaining. I would be concerned about getting the old ethanol fuel out of the fuel injectors if it has sat or will sit for a while. They tend to clog with that fuel if non-running and new AC Delco fuel injectors are expensive. You Tube has good videos on how to pressure clean fuel injectors but only use the non flammable cleaners to prevent a possible shop fire and injury.

I do believe you will need to do some tuning inside your powertrain control module to keep from running lean with that camshaft. Running lean is running hot and can melt a piston top.

The 150,000 mile 5.3 LM7 inside my 1970 El Camino runs better and better with time and use of strong fuel system cleansers. The engine had mild spark plug fouling problems with the middle two passenger side cylinders and worse with the far rear passenger side cylinder. Now, with a little over four hundred miles on the motor inside my EC, these problems have resolved themselves. I'm guessing stuck oil rings that unstuck with some persistent rides up around 3500 rpm and that fuel system cleaner. The unknown previous owner of my engine and trans might not have ever gotten this engine to a very high RPM . . . . ?????

Rick

T4nkz

Hey Rick I appreciate the feedback! I'll have to keep the fuel injectors in mind. It has been sitting for a bit, but I am going to check out some videos on youtube and hope it is not too late. By the way what fuel injectors do you recommend?
Have you had some troubles with the cams I am going with? I'll look into it just in case though.

But hey that's a good thing if the previous owner didn't go to very high RPMs! Means the motor is still strong and lacked the abuse.

Also again I appreciate it, saved me a $1800 rebuild.

01CamaroSSTx

iTrader: (3)

Hell that motor is just getting broke in. You could probably get away with just installing the TSP spring kit on the heads and reusing the valves.

LLLosingit

iTrader: (4)

They aren't expensive on E-bay Sets as long as $39.99 shipped

B52bombardier1

I find it hard to believe that the Ebay link above for fuel injectors is for a set of real AC Delco parts. That's got to be for Chinese copies, not the real deal. I'd sooner remove fuel injectors from a junkyard motor, test their resistance at the junkyard and revive them here in the shop than buy a set of suspect injectors off of Ebay. Don't get me wrong, I buy stuff off EBay all the time. The deal at the link above is too good to be true for me and I despise having to perform engine work tasks twice.

Rick

T4nkz

Really now? That’s good to know. Sadly since i already have the valves and retainers I might as well use them.

The ratings seemed good and a lot have sold. So who knows. How much do they usually go for? I see no one goes with any aftermarket ones.

LLLosingit

iTrader: (4)

They are real GM parts, I've bought from them a few times over the years, They were selling Camaro Brembo Calipers for less than people were getting for there used ones. I've bought Calipers/Pistons/Rods/Heads/Injectors. They were all OE Parts, That seems to be all they sell.

B52bombardier1

Please check the fuel injector price link below for the online prices of my favorite local auto parts store - ABC Auto Parts. Yes, I won't pay that price standing at the parts counter for the 5.3L LM7 engine injector and would likely get it knocked down by one third. But that listed price is for one single (not a set of eight) AC Delco 26 pound Multec fuel injector part number 17113582. I will save you the trouble - its $158.99.

http://www.abcauto.com/ShopByVehicle...=True&rewrite=

Even the remanufactured AC Delco single injector price of $53.99 is far higher than the Ebay price for a set. And that still requires either the turn in of a core or a ten dollar fee.

That Ebay price for a set has a foul odor for me regardless of good reviews or not.

Rick

LLLosingit

iTrader: (4)

LOL, You can pay what you want but I'm not paying those prices lol, They are an OE parts supplier and likely cleaning out old stock. The Brembo calipers I paid $200 shipped for a set of 4 with brake pads, I shared the link with quite a few people and they also bought them and other parts. List price was $2300. They are all OEM parts.
Example LS7 Crankshaft they sell on E-Bay for $399Same Crank on their Website for $599 And the same Crankshaft being sold by a GM Dealer $984.46 They are all the same crankshaft.

LLLosingit

iTrader: (4)

Here's a perfect example, They sold 433 sets of 5.3 Pistons with rings and pins for 100.99 and they say they are OEM and I don't doubt it one bit.... Who is going to bother making fakes of them? Even if they did they sure wouldn't make any money selling them for $100 a set. lol They are moving old stock.

Justinmoody

I bough some 243s for my cammed 5.3. Had them milled .005” what size push rods would I need?

LLLosingit

iTrader: (4)

You'll need to measure and find out.