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5.3 Build masters in here!
I just acquired a 2005 LM7 5.3 with Gen 4 internals 24x for a couple hundred bucks for my boosted 02 Camaro SS.
So the oil pump in it failed but the engine never knocked or completely lost oil pressure, just lifters clattering so the previous owner is recommending cam bearings. Main/Rod bearings look good.
The goal is 700 rwhp at about 16 lbs. of boost w/ a T7875 max rpm 7K.
The budget is tight so if I don't need I won't do it.
How should I prep this short block?
Clean it up, gap the rings and roll out?
Total Seal rings worth the investment for power and crank case pressure reduction?
Rod bolts?
King Bearings?
Any real world input and expert advice is always appreciated. Cheers!
Check the cam bearings and replace if they are trashed. If the bearings are done, cam might be too.
Replace lifters with LS7 lifters.
Check bottom end bearings and replace with stock.
I wish the rod bolt mentality would go away. You don't need rod bolts unless you're spinning the motor to the moon. Power doesn't kill the rod studs, RPM does.
Your goal is easily obtainable with just a cam and stock everything else. I wouldn't even worry about the rings honestly. If you feel compelled, then you can gap them.
How can you tell if the cam bearings are trashed?
The previous owner reused the cam in another short block and its still in use.
I'm going to reuse my LS7 lifters out of my LS1 since they're fairly new.
I'm hoping the bottom end is okay since it never knocked or got below 10 psi, the previous owner is a friend so I trust his info that and the bearings will tell me otherwise.
Wow so leave the stock rod bolts and rings, I love it. That means if I'm lucky I can clean this guy up and slide it in along with my 10 lbs. spring lol.
I want to at least check the ring gap, if I don't and it pops I'll be very upset with myself since I was right there.
A good friend also suggested a HV oil pump and they're so cheap it seems like good insurance.
Will my LS1 head studs work on the LM7?
Bummer, its a short block only so I'll have to slide a piece of wire down the hole and measure then.
I've got taps and dies, could I just shorten the ones that are too long?
Bummer, its a short block only so I'll have to slide a piece of wire down the hole and measure then.
I've got taps and dies, could I just shorten the ones that are too long?
Go sloppy style and just stack washers on the ones that are too long! Just kiddin'! Clean it all real well, open the gaps if it'll make you sleep better. Clean it again as reassemble. Not sure the obsession with HV oil pumps unless clearnaces are opened up, but either way run an extra quart and a half in the pan. JMO, I am not (by any means) a master.
Last edited by 3 window; Aug 19, 2016 at 12:01 PM.
Well now I have another concern. The dished pistons on the 5.3 combined with the 72cc chamber on the CNC ported 317's I have significantly lower the compression and according to some threads I've been reading cause the combo to be a dog out of boost. I'm currently running a 4.10 gear but may be switching to 3.73. Has anybody had this experience with a 317/5.3 combo?
my 5.3 made great power at first on 853 heads the shitty ones everyone says u cant use mls gaskets on but guess what not only did i use mls gaskets i re used them on my new motor so i have defied that lie twice with one set of gaskets but be careful clean it really good if u think it needs replaced replace it i had good luck on my first 5.3 then when i sent to have it bored to ls1 bore size and have studs and new bearings forged bottom.end put inside i threw another stock 5.3 in it had good bearingd but was dirty bad i slapped it together with my boost cam and heads made about 40 miles and when i put 10lbs on it the first time i dropped oil pressure and three rod bearingd and it ran flawlessly before that these motors are not invincible but done right are good to go also i run a cheap on3 88mm and it blows the tires off at 13#s about 120mph so i saved money on a cheap turbo that is still.running strong a catch can will be your best friend and i believe crank case pressure killed the stock 5.3 i had the second one had bad blow by shortly after the turbo went on
Just curious but why the switch from the current motor? Honestly I would keep the 5.3 as a spare for if/when the stock block gives up the ghost. I have 180k miles on my stock bottom end and have done 748 rwhp with it cutting it short in revs at 6500ish and 15 lbs of boost and low timing. Compression calculators put me at about 9.0:1 for compression so lots of room for it to be safe. Out of boost it is down from where it was with the NA cam and 243 heads but not as bad as you would think. 2800rpm comes quick and builds the boost and any difference you might have noticed NA is soon gone.
If your worried about low compression you can mill the heads to bump it up a bit with the dished pistons.
Rawr256 hit it pretty much right on. Any "out of boost" driving will be overcome quickly with the gas pedal. If your boost starts around 2800 or so, you won't even notice it because the increase in torque starts even before you build positive pressure.
I'm not looking to make the switch right away, I just came across this good deal so I jumped on it. I haven't found any 5.3's with the good Gen 4 internals and a 24x wheel.
I just want to get a good idea of what I need to do to get it ready over the next year or so. Somewhere between having it fully built and hosing it off and slapping it in lol. I'd like to put a little money into it and have it ready should my current engine expire, I'd prefer not to blow it up.
The number 7 piston edge got beat up when it dropped a valve on the previous owner so that's always in the back of my mind when pushing it hard.
I really don't even know what it makes, I just drove it with the T7875 and its stupid fast lol. Now I lose traction at the top of third at about 85 mph at about 7-8 lbs. of boost. It feels like it lays over a liitle bit at 6K and up but that may be the tune or the cam. I wouldn't mind upgrading the pump and putting the 10 lb. spring in now that I have a spare bullet.
I'm not gonna worry about the compression with the smaller 75mm turbine either.
Here's some pics of the guts lol. 130K on it i think.
Pull it apart, clean it, replace the number 7 piston and reassemble. OR sell it to me and I'll do it. That's a great foundation to start with, dished pistons and gen IV rods. Looks like an LM7.
The 5.3 pistons are perfect, its my ls1 that's got a beat up piston. Well good, I'll tear it down this winter and hopefully all my bearings will be in good shape. Recommendations for cleaning? A friend of mine suggested soaking the pistons in diesel fuel. What about cleaning up the block? No on the HV oil pump too?
Diesel will work. I used PineSol. As for the block, beleive it or not, powder Tide. Doesn't leave any soap residue or rusty appearance. Get a good block brush set and be sure to get in all the nooks and crannies. Take all the oil galley plugs out and be sure to blow through everything. It can't be clean enough. Unless the bearing or rod side clearnaces are opened up, I don't see a need for a high volume pump. But that's my opinion. EXTRA OIL IN THE PAN!
Could always replace the dished pistons with genIV 4.8 flat-tops to help with the compression a little bit. Especially since you want to open up the rings anyways, and since you shouldn't be wasting money on rod bolts/resizing rods.
I personally like high volume oil pumps more than high pressure pumps, but the engine has to be set up for it with looser tolerances and a larger oil pan. For a build like this I would just run a ported stock pump.
Other than that, throw this thing in there and have fun.
This is great info guys!
So my buddy who sold me this engine said the oil pump failed and the lifters started to clatter.
It never lost oil pressure or knocked since he was monitoring it but he did tell me it would probably need cam bearings. I've never seen failed cam bearings in an engine and am a little skeptical it needs them.
If I open the rotating assembly and visually inspect the cam bearings and all looks good is there anything else I should look for?
What should I gap the rings to as well? I've seen .026 upper/.028 lower recommended.
This brush set? https://www.amazon.com/Moroso-61820-.../dp/B000CONYTS
I usually cover my block in a nice combination of Purple Power and Eagle One aluminum wheel cleaner, and then take it to the car wash. The high pressure sprayers there do wonders on dirt/grease/oil build up.
For rings, I use .026 upper for pump gas, .022 for E85. Almost every 2nd ring I've measured was already gapped around .026 so I didn't touch them.
I usually cover my block in a nice combination of Purple Power and Eagle One aluminum wheel cleaner, and then take it to the car wash. The high pressure sprayers there do wonders on dirt/grease/oil build up.
For rings, I use .026 upper for pump gas, .022 for E85. Almost every 2nd ring I've measured was already gapped around .026 so I didn't touch them.
This ^^^ and yes, that's the brush set. I went .028 on my rings in the case I run pump gas (I'm on E85 now).
Perfect, I will be on pump gas for the duration and then some meth when I go for broke so .026 it is.
Is there any down side to running a HV pump on an engine that isn't spec'd for it?
I wouldn't mind the additional volume and the price is half of a stock ported pump, if I'm only looking at a slight hit in power production I'm good with that.
Could I port the pump I have now or buy a new one and port it?
I've ported iron and aluminum heads before and have all the tools is why I ask.
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Boosted 5.3 Build Masters In Here!! 
