found some heads

[ak diesel driver]

So I found some brand new still in the box from the dealer heads here locally for a pretty good price, $400 for the pair. So my ?s are
1: are there any original castings to avoid
2: it has 1 dot precups which are NA so if I have them machined will it still leave me at the higher NA compression ratio or will machining the mouth drop it to turbo levels? I'm assuming it will not drop it as much as I'd like.
3: these heads are not assembled but come with all the parts in the original factory packages, so my ? here is what's the best valve stem seal to use?

 

[ak diesel driver]

Nobody? Guess I'm on my own then.

 

[Will L.]

I don't know the right answers here but want to say congrats on the find! And I'll talk to you, I'm not mad at ya!

I can't imagine opening up the precups would change it much at all. What about selling those and finding diamonds in place? Use $from sale to offset the other.

I've never heard of castings to avoid, i believe most of the cracked heads are because of the now cooling system design problem. I know the metallurgy change in the optimizer heads helped keep them from cracking in the overheating situations better. But I wouldn't be afraid to run them, especially at that price.

Valve stem seal no clue. I don't think I have ever done any reading on them for any engine. Kinda just threw in whatever I found at the time.

Ok, I spoke up, now someone smart needs to...

 

[Burning oil]

I know what you mean.
Have not heard of any heads to avoid. I think they are all (GM castings) susceptible to cracking. AMG heads are a big improvement. And P400 have hardened seats.
For $400 jump on em.
Try .010 head gaskets? and hard seats?

 

[Burning oil]

Will must have clicked reply a second before me

 

[Will L.]

Quick Draw McGraw was my favorite horse growing up

 

[ak diesel driver]

so if memory serves the P-400 are actual hardened seats vs the stock induction hardened cast iron

 

[Burning oil]

Its a hardened seat insert on P400 as I understand. Helps stop cracking between the valves.

 

[ak diesel driver]

Picked up those heads

 

[WarWagon]

On new heads just the factory o ring seals. Positive control on the exhaust saves oil, but, less oil is more guide wear. Oil is cheap, heads are ~$400.

The compression ratio being higher will help start the engine in the cold. The precups IMO don't affect it much.

I wouldn't bother with the precups unless you are running a non-GM turbo. Absolutely do them with non-GM turbo's like the ATT! With a GM turbo the NA precups may smoke slightly more, but, no MPG or power difference.

 

[Burning oil]

Nice.