5.3 build help
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Teching In
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5.3 build help Hello guys I recently picked up a junk yard 5.3 doing a rebuild on it to swap it into a foxbody mustang. Changing head gaskets and reringing pistons and main and rod bearings and just gasket it up mostly. Plan is to build motor for turbo later goal is around 550 WHP after turbo but run it na for now. I have everything stock right now with the truck intake. Which things are worth upgrading and what isn’t? Someone people say with stock heads and cam and intake just upgrade the springs and it’s good for 500HP at around 10 pounds of boost. So any build combos you guys can put out don’t want to spend to much on it as of now. Also is it worth throwing the ls9 7 layer head gasket on it?
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From: Central Cal.
You might think about opening ring gaps if running a hair dryer is in its future. Other than that and refreshing gaskets, etc., you're good to go.
Good valve springs and LS9 head gaskets, along with a new oil pump would be worthy upgrades.
Good valve springs and LS9 head gaskets, along with a new oil pump would be worthy upgrades.
Thread Starter
Teching In
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what ring gap would you recommend? And just valve springs in the heads? How good are these rockers in these heads?
Don't need to open the rings up for 10lbs and your rocker arms are fine up to .600 lift now it certainly wouldn't hurt to add some more ring gap and upgrade the rockers if going bigger. I'd be more concerned about investing into those things that will do a better job of holding it all together.
Thread Starter
Teching In
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Don't need to open the rings up for 10lbs and your rocker arms are fine up to .600 lift now it certainly wouldn't hurt to add some more ring gap and upgrade the rockers if going bigger. I'd be more concerned about investing into those things that will do a better job of holding it all together.
I'm no cam guru but as far as rocker arms go I wouldn't be too concerned unless I was exceeding .600 lift and/or having to run dual springs. Maximum lift for a stock rocker arm is .660 if I'm not mistaken and at this point modifying the stock rocker arms with aftermarket trunnions would be recommended if not going to aftermarket one's all together.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
Build for dependability first. Heads, cams, etc. don't matter as much with a turbo as you can build boost to whatever power level you want.
Watch some Richard Holdener videos about boost and you get that message on the regular.
Watch some Richard Holdener videos about boost and you get that message on the regular.
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Don't need to open the rings up for 10lbs and your rocker arms are fine up to .600 lift now it certainly wouldn't hurt to add some more ring gap and upgrade the rockers if going bigger. I'd be more concerned about investing into those things that will do a better job of holding it all together.
I'd gap the rings. I'm not going to give a recommendation because thats like suggesting what cam is the best one....but you can go to cp pistons website and read this:
(I gapped mine at .024 on the top ring and .026 on the second ring)
Q: RING END GAPS?
Due to the wide variance of expansion rates typical of power adders (nitrous, turbos, etc.), air cooled versus water cooled, marine applications, etc., it can be difficult or impossible to give ring end gap recommendations that will be accurate across the board. Please be aware that the information provided is only a guideline and that any concerns should be addressed with your engine builder. All information is provided in inches of ring gap per inch of bore. EXAMPLE: A recommended ring gap of .0040 per inch on a motor with a 4.000 inch bore would yield a ring end gap of .016 inches as .0040 x 4.000 = .016DOMESTIC AUTOMOTIVE: Normally Aspirated (no power adders) up to 600hp.
- Top Ring = .0045 - .0050 per inch of bore
- Second Ring = .0050 -.0055
- Oil Rings – Actual gap = .015-.050
DOMESTIC AUTOMOTIVE: Normally Aspirated over 600hp and turbo/nitrous applications below 750hp.
- Top Ring = .0050 - .0055
- Second Ring = .0055 - .0060
- Oil Rings – Actual Gap = .015 -.050
DOMESTIC AUTOMOTIVE: Turbo/Nitrous applications above 750hp.
- Top Ring = .0060 - .0070
- Second Ring = .0070 - .0080
- Oil Ring – Actual Gap = .015 - .050
Last edited by Kfxguy; Mar 15, 2021 at 12:40 PM.
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No. Everyone turns it up until they run out of fuel pump. If you have the engine apart, you may as well open the top ring gap to 0.028" - 0.030" or so.
Bang for buck for 5.3 I would say cam and valvesprings (doesn't need to be a big cam, , a proper tune and get a program to retune your stock ECU, one of those Doorman reproduction intakes, a bigger throttle body, and headers. That will get you to where you have saturated the stock heads.
Bang for buck for 5.3 I would say cam and valvesprings (doesn't need to be a big cam, , a proper tune and get a program to retune your stock ECU, one of those Doorman reproduction intakes, a bigger throttle body, and headers. That will get you to where you have saturated the stock heads.