LQ4 With 823 Heads
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Teching In
Joined: Jun 2025
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LQ4 With 823 Heads Alright, just looking for some insight on the motor I'm building for my roller 2006 GTO 6 speed. I picked up an LQ4 motor from an 04 GMC HD and I've got it torn all the way down. I got a smoking deal on some stock 823 heads and a complete LS3 intake that I want to use. Now I know the short answer to my problem is just measure, but this is my first LS build and I'm trying to order everything once. My plan is to replace cam, main, and rod bearings so they are fresh while I have it stripped down this far and I want to ditched the LQ4 dome pistons for a set of WS6store LQ9 style flat-top pistons to gain some compression (I have floating pin connecting rods). I'm trying to spec out the best cam that won't run into PTV clearance problems with flat tops and the 823 heads. I was looking at the SS2 cam 228/230 duration @ .050” with .585”/.585” valve lift and 112 degree lobe separation angle? I saw Richard Holdener run it on an LY6 motor but those have factory dished pistons with valve reliefs. I don't want to leave anything on the table when specing out a cam, I'm hoping for high 4's to the wheel
That’s an odd combo. Probably not going to get an easy answer. You’re going to need to assemble the short block install the heads, and measure. The only tip I can give you, is save the original head gaskets and head bolts for your mock up measurements. Then use new head gaskets and head bolts for final assembly. As far as can choice, it’s important to know what transmission you’re using. Manual? Auto? What stall tc? Also install new cam bearings while it’s taken apart.
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Joined: May 2023
Posts: 418
Likes: 138
From: Franconia, PA
Alright, just looking for some insight on the motor I'm building for my roller 2006 GTO 6 speed. I picked up an LQ4 motor from an 04 GMC HD and I've got it torn all the way down. I got a smoking deal on some stock 823 heads and a complete LS3 intake that I want to use. Now I know the short answer to my problem is just measure, but this is my first LS build and I'm trying to order everything once. My plan is to replace cam, main, and rod bearings so they are fresh while I have it stripped down this far and I want to ditched the LQ4 dome pistons for a set of WS6store LQ9 style flat-top pistons to gain some compression (I have floating pin connecting rods). I'm trying to spec out the best cam that won't run into PTV clearance problems with flat tops and the 823 heads. I was looking at the SS2 cam 228/230 duration @ .050” with .585”/.585” valve lift and 112 degree lobe separation angle? I saw Richard Holdener run it on an LY6 motor but those have factory dished pistons with valve reliefs. I don't want to leave anything on the table when specing out a cam, I'm hoping for high 4's to the wheel
