So I bought this 5.3 the other day. I didn't pay much for it because I didn't hear it run. Has 130k.

Anyway, so I got it on the stand. I ripped the exhaust manifolds off, starter, accessories, etc. The kid left the torque converter on, so I went to remove that. I noticed I could rotate the motor by hand easily.

I took the torque converter off. I can grab either the flex plate, or the crank pulley with two hands and completely rotate the motor over.

Now considering everything I'm used to is a PITA to rotate even with a rotating tool that hooks on the flywheel, I'm kinda thinking this thing has very low compression?

Or it's got the lowest drag piston rings on the planet.

But since I don't know jack about LSx stuff, I figured I'd ask.

I paid $150 for this motor complete. I figure even if it needs a rebuild, that's a good price for a core.

-- Joe

 

My LS1 I know was running when pulled. It seemed pretty easy to turn with the heads on but I don't know that I could have done it by hand. With the heads off sure. After rebuild it was much tougher, but I also bumped compression and some other stuff.

Compression is a little lower on the truck motors, depending on the heads I think around 9.5-1. You sure the heads weren't off and not properly put back on or something like that?

 

It is easy to tun with all the plugs out. Just friction at that point, no compression.

 

Mine rolls over very easy with the plugs out. No problem grabbing the crank pulley and spin it over and it's a very low mile factory crate motor.

 

Plugs are all in.. I'll take a video later for you guys to see.

If I have time I'm going to put the starter on it and do a compression test. I'm guessing something north of 140psi is stock for a early 5.3?

I'm thinking of just getting a 5.7 rotating assembly and boring the block. An iron block LS1 would be a nice boost motor.

-- Joe

 

Just FYI if your going to start rebuilding/machining ect Summit does have the GM 5.3 bare block for $300

https://www.summitracing.com/parts/s...Fc5ZhgodZEAIQQ

Good deal if you need one.

 

I saw that, but it's $150 to ship it to my door, then I gotta do freeze plugs, cam bearings, galley plugs, and all that and final hone.

It's cheaper to machine the one I have.


I gotta do more reading though. I've not done any LSx stuff. I might be making some assumptions of what it's capability is..

-- Joe

 

here

 

Do you feel air coming out of anywhere besides the exhaust ports? That seems way too easy.

 

No, but I need to get someone to turn it while I check.

If I have time tomorrow night I'll do a compression test but, yeah. I was bummed. But for $150 I can't gripe.

I figure I could either make a low boost 5.3, or maybe a 400hp naturally aspirated 5.7 out of it.

-- Joe

 

That engine is toast.

 

Yeah that's kinda what I was thinking.

-- Joe

 

Yeah that was too easy to spin

I can spin most used truck motors over by grabbing the balancer by hand, but its slow and I have to let compression bleed off as it turns

 

Well, I guess It will be a core for a future project.

-- Joe

 

For $150 youve got in it, you could turn it in to most rebuilders and make money. They're cake to overhaul, so dont sweat it

 

I have not done one before, but I figure it's time to start. Really thinking of doing a 5.7 build. I here you can bore them out and stick ls1 rotating assembly.

-- Joe