I saw the other post you just replied to. I have a 5.3 Ho in the shop with 799 casting heads on it. They have the 2" intake valves are the ports the same as 243? What about the chambers? Is this a good head to put on a mild 6.0 with a 205/212 .540/.540 116.5 CL cam.

 

I got to get up close with the hybrid prototypes at the GM plant here in Arlington and they had 799 casting heads on them as well.. Not really an answer to your Q's but might be interesting to know.

-Lurius

 

The 799 casting was mainly used as a pre production head. I'm not sure how many early ZO6's were shipped with them, but I don't think too many because I have only seen them on a very rare ocassion. They are virtually the same as the 243 casting. In fact, I used a pair of 799 heads to test our Stage 2 LS6 program on and the cleanup was complete. Compression ratio will end up with around 10:1 with a stock volume chamber. Your cam is a bit on the small side, but it will make boat loads of torque from the crack of the throttle to 5500 rpms.

Let me know if this helps.

Good luck,
Richard

 

These heads came off a stock 2005 5.3 HO. I gueas GM must have put those castings back to work.

 

What does a 5.3 HO come in? The first year SSR??? How's it different from a regular 5.3L??? Never heard of it...

 

This motor came out of a 05 4x4 ECSB. I beleive it's an L33 somebody correct me if I'm wrong. It's all aluminum and has flat tops with these heads. It's factory rated at 10:1 compression and 305HP

 

Yep, thats all correct from what I researched. I just swapped my 4.8 for an L33 motor and I can tell you there is no comparison. The truck is a completely different animal now.

 

If I understand correctly, GM started useing that motor in 2005 and was only in the extended cab 4x4 trucks for that year and not sure if it has changed since. It's is a all aluminum engine.

 

Putting the 799 heads on a 5.3l engine is like putting on a ported set of truck heads. Much improved breathing on the LS6 heads. I'll keep a mental note of the fact that 799's have ended up on some 5.3l engines. Thanks for the info.

Regards,

Richard