I need to order some head gaskets for my forged 4.005 bore LQ9 with 317's and ARP heads studs. I'm planning running 15 lbs of boost max. I've heard good things about the GM 5 layer MLS 4.020 bore LS2/L76 MLS .051 head gaskets #12589227 but I wanted to get your recomendations. Since it basically a stock bore with a honing, I want to make sure I don't use too big a bore head gaskets and sacrifice gasket surface between the cylinders.

Also, dry or with copper spray? I've read yeah or nays both ways. The block and heads will have a fresah surfacing so I nad the machine shop both thought the copper would be a benefit.

Rick

 

im running the stock 6.0 mls gaskets dry... have run 16 psi a lot, and have run as high as 20 psi. you will be good with the mls for sure.

 

Its a toss up between ls9 7 layer or 5 layer.Far as not enough gasket to seal thats not been an issue in high hp its the threads on the head bolts or studs stretching allowing cylinder pressure to escape so no matter how much gasket you have between the coolant passages or atmosphere the gasket will not save you.

Imo ls9 ftw only cause its the latest fad and we need more R&D on them.LOL

 

I have stock 5 layer 6L MLS's copper sprayed with ARP studs 10lb/ft over tq'd

 

Thanks for the feedback. I'm shooting for 9.0-9.2:1 compression. I ordered Wiseco K444X05 -11cc dish pistons so once the shortblock is assembled, I'll measure the deck height and then see if the GM .051 thickness keeps me in the ballpark. I haven't surface the 317's yet so I could always UPS them down Patriot and have them freshen them up and polish the chambers up to 74cc.

Rick

 

my WCCH 317s were opened up to 74cc, and with srock deck height and my Probe pistons I'm dead at 9:1 CR

 

I thought it was Patriot but it might have been WCCH that had a post about opening 317's up to 74cc.

9.0:1 sounds like a good compromise for a daily driver. Still maintains decent torqu off boost and with enough Meth, I'm pretty confident it can be tuned to run 14-`15lbs my a decent amount of timing. I'm just looking forward to the day I can turn it up from my current 10lbs and see what the kit can really do.

Rick

 

With these pistons did u have to rebalance the bottom end