5.3 Newbie
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Teching In
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5.3 Newbie Trying to learn as much as I can about what works and what don’t. I have a 04’ 5.3 and It has 862 heads on the motor now and my question is can I run LS3 heads on this motor? I can get a good deal on them, just don’t know if they’ll work? Don’t know if it’s worth sending these 862 heads to the machine shop to be checked out and resurfaced or buy the fresh LS3 heads. Any advice is appreciated 👍🏻 Thanks everyone.
The LS3 heads won't work. They are for a 4" bore or larger motor so the valves will hit the cylinder walls if you install them on a 3.78 bore.
If they did work, they would still be a bad match. They have large ports for larger displacement. They also have large chambers and would drop your compression so low you'd have a really doggy 5.3
You need much smaller heads for a 5.3
If they did work, they would still be a bad match. They have large ports for larger displacement. They also have large chambers and would drop your compression so low you'd have a really doggy 5.3
You need much smaller heads for a 5.3
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Teching In
Joined: Mar 2019
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The LS3 heads won't work. They are for a 4" bore or larger motor so the valves will hit the cylinder walls if you install them on a 3.78 bore.
If they did work, they would still be a bad match. They have large ports for larger displacement. They also have large chambers and would drop your compression so low you'd have a really doggy 5.3
You need much smaller heads for a 5.3
If they did work, they would still be a bad match. They have large ports for larger displacement. They also have large chambers and would drop your compression so low you'd have a really doggy 5.3
You need much smaller heads for a 5.3
Thanks for the info, So are the 862’s worth putting $$$ into?
They’re good heads to go on a 4.8/5.3L shortblock. The chambers are small so they help get the compression up on a dished piston 5.3L. I wouldn’t hesitate to have a valvejob cut for and install 2.00” intake valves. I did the same thing with my 4.8L.
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TECH Resident
Joined: Apr 2010
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From: Central Texas
I sent my 862's to Texas Speed to get their CNC wok done along with larger valves. going on a 5.3 .040 over size with LS6 intake and their (Texas Speed) truck cam. They look really well done. FYI
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Teching In
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If you don’t mind me asking, how much does it cost with shipping to do something like that?
TECH Resident
Joined: Apr 2010
Posts: 926
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From: Central Texas
It;s on their web site and I live close enough to take my heads down for them to use, which is a difference in price. Also it depends which valve springs,retainers you want. call them, they are nice folks..