JJMclure

Hi guys, I have a question regarding heads on the LQ4/6. Being in the uk I am planning on buying my engine from an importer who specialises in LS engines. Did the LQ4/6 ever come with rectangle port heads? Which are the best heads to look out for on the truck engines?

Jovozx12

iTrader: (6)

I dont think so. The rectangle port heads came off the LS3 6.2L motors. I dont think they ever came on a 6.0L.

conan

iTrader: (5)

^^^

The LQ4 or the LQ9 will have cathedral port's. They also got the #317 casting heads. The difference between the 2 engines is the pistons, LQ4 has a dish piston and 317's for 9.5:1 compression. The LQ9 has a flat top piston with 317's for 10:1 compression.

What engine are you getting LQ4 or LQ9 ?

Sales1@Texas-speed

There were some 6.0 liters that came equipped with the square port cylinder heads. The LY6 for example had square port cylinder heads.

JJMclure

Thanks for the responses, I plan on getting an lq4 once I have raised the necessary funds. Cheers guys!

Sales1@Texas-speed

No problem. Feel free to give us a call if you need help with anything.

garygnu

the 317 head is a ok head,but benefits from milling to gain some compression.what kind of octane can you get at the pump?

Sales3@Texas-Speed

iTrader: (2)

No matter what cylinder head you decide to use, I would make sure you know what camshaft you are going to go with first, so you can determine how much you will be mill without having to flycutt the pistons (if that is even a big deal to you).

USMC5811

iTrader: (2)

What oil should i use for a new 408 to break it in? GMHTP magazine said to run coventional oil for the first few thousand miles to help the rings seat to the wallls better. But what weight etc?

JJMclure

garygnu - I can get 93 or 97 at nearly every petrol station over here, I'm planning on getting the engine in and running in standard trim then fitting some rectangle heads with a carb style manifold cam etc. this is a pic hopefully of the car it's going in