5.3L Heads question and answer section

**95camaroZNC** · 08-22-2010, 03:01 PM

I keep having questions im finding and getting no answers, I know other people have questions as well or will at some point so i figured making this thread would be a good way to save time and trouble down the road. If not

Next of which being, what size Valves do i need to use in this, ive read bot 2.02/1.57 and 2.00/1.51. Also curious as to which push rods i need to be using. The heads are going to be replacing my current heads on my ls1. Also what lifters i should be looking for would be great as well.

**bills98ta** · 08-22-2010, 07:20 PM

I installed 2.02" & 1.6" valves in mine using the stock 5.3 head seats. That is the largest you can go with the stock seats I'm told. They can be opened up with the valve grinder for better flow. As far as push rod length, that will be decided after the heads are finished. And depending on how much they are planed or decked.

**95camaroZNC** · 08-22-2010, 08:08 PM

Originally Posted by bills98ta

I installed 2.02" & 1.6" valves in mine using the stock 5.3 head seats. That is the largest you can go with the stock seats I'm told. They can be opened up with the valve grinder for better flow. As far as push rod length, that will be decided after the heads are finished. And depending on how much they are planed or decked.

See i was considering reusing my stock intake valves because they look pretty good and dont take too much of a beating, but replacing my exhaust valves because they look awful from taking them off these heads and i heard the one piece valves have less of a chance of separating. So for the exhaust valves i should go with a 1.6" valve?

**bills98ta** · 08-23-2010, 03:16 AM

I assume you want to use the stock LS1 1.97 valves. That would work, & also with the 1.6 too. You can find them fairly cheap on ebay, for both.

**BIG_MIKE2005** · 08-23-2010, 10:48 AM

I had Bo White port/polish & mill (.018") a set of stock 5.3 heads for me. He also swapped in 2.00 intake valves but we kept the stock exhaust valves. Gunnar@Patriot flowed and assembled them with their double spring kit. The heads outflowed stock LS6 heads & I have been running them for 3yrs/50k miles without a single issue.

**LoneGunman** · 08-23-2010, 02:38 PM

I don't mean to jack anyone's thread here, but why 5.3 heads? What's so great about them? Why not LS6 or LS2's?

**tatertot91** · 08-23-2010, 02:41 PM

Originally Posted by LoneGunman

I don't mean to jack anyone's thread here, but why 5.3 heads? What's so great about them? Why not LS6 or LS2's?

Cheaper, higher compression

**bills98ta** · 08-23-2010, 02:51 PM

They take a lot more porting, but it's worth it ! I have +12cc dome pistons, so I'm at 14:1 CR !!!

**LoneGunman** · 08-23-2010, 03:11 PM

I see. So it's like the equivalent of putting 305 heads on an old 350? An old circle track racer trick to gain more compression.

**95camaroZNC** · 08-23-2010, 09:09 PM

Yep, and spray LOVES compression. Ill keep this thread updated as my build progresses. Ive gotten some really good advice here. Im taking my heads at the start of next week to be milled. Porting kit should show up end of this week and springs next week.

**BIG_MIKE2005** · 08-24-2010, 03:55 AM

Originally Posted by 95camaroZNC

Yep, and spray LOVES compression.

This is why I went this route. When I was assembling my combo I wanted a cam that liked nitrous & heads that would bump my compression, without breaking my bank. The 5.3 heads fit the bill perfect since they will outflow stock LS6 heads after a good port/polish job along with the compression bump.

I still intend to hit this combo with a 150 dry shot, but at the end of the year I might possibly switch to a new EPS custom grind cam to maximize my combo.

For what its worth, I'm running 89 pump gas (100% gas only) in mine without a tune & it runs just fine & strong. I have a Aeroforce scan gauge set to display knock & the only time I get knock is if I'm at too low of RPM's/too high a gear & step on the gas makin the motor wanna bog for a second. If I'm accelerating thru the gears I get absolutely none & the car pulls hard. I'll run 91 after my tune but 89 hasnt let me down yet or caused any issues.

**95camaroZNC** · 08-24-2010, 02:34 PM

Originally Posted by BIG_MIKE2005

This is why I went this route. When I was assembling my combo I wanted a cam that liked nitrous & heads that would bump my compression, without breaking my bank. The 5.3 heads fit the bill perfect since they will outflow stock LS6 heads after a good port/polish job along with the compression bump.

I still intend to hit this combo with a 150 dry shot, but at the end of the year I might possibly switch to a new EPS custom grind cam to maximize my combo.

For what its worth, I'm running 89 pump gas (100% gas only) in mine without a tune & it runs just fine & strong. I have a Aeroforce scan gauge set to display knock & the only time I get knock is if I'm at too low of RPM's/too high a gear & step on the gas makin the motor wanna bog for a second. If I'm accelerating thru the gears I get absolutely none & the car pulls hard. I'll run 91 after my tune but 89 hasnt let me down yet or caused any issues.

Gonna run the 5.3 with a high lift cam and .650 lift springs. My heads, sadly didnt come with rockers so im having to find some.

**bills98ta** · 08-24-2010, 02:38 PM

Here's a pic of my chambers ready for 2.02 / 1.6 valves...

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**bills98ta** · 08-24-2010, 02:41 PM

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**95camaroZNC** · 08-24-2010, 03:46 PM

Nice

**BIG_MIKE2005** · 08-25-2010, 03:27 AM

Originally Posted by 95camaroZNC

Gonna run the 5.3 with a high lift cam and .650 lift springs. My heads, sadly didnt come with rockers so im having to find some.

Make sure you triple check your PTV. I'm not sure what the max lift/duration you can run with the 5.3 heads is, but if they are milled you'll lose room.