Ok guy I've been on the N20 section and have gotten nowhere.
I need some advice on what SPEC of a piston I should go with. Like how much negative or positive I should go. It will be a .030 over piston with a stock stroke and milled and ported 317's since I can't find anyone to trade for some 5.3's... Any info would be awesome!... Also it will be for a 200shot if that helps out with the specs.

 

Too many variables not listed.

My advice, don't build your engine from internet advice. Too many wannbe engine builders out there that regurgitate info they heard from their brothers, uncle's friend. Talk to an engine builder/machinist that has qualified experience with your engine platform and intended use and has actually built them, not a reseller.

Who's doing your machine work?

Mike

 

Well I was just trying to get an idea on what to look at. Not really trying to go with what someone tells me.
Jeffs machine shop down here. John Had his motor done there.

 

Do you know what your compression will be with those heads after milling them? Have you picked a head gasket thickness?

I'd shoot for 11-11.5:1 compression and whatever piston you pick, should probably be 2618 alloy with a 200 hit.

Mike

 

Well I should be right around there for compression. I'm going eaither .020-.030 gasket. Thanks mike you're the first to give me something to look at

 

If your engine builder isn't helping or isn't exactly sure another option could be calling tech for a couple of the quality piston manufactures and get input from them as well.

How goes the build/teardown ?

 

I got the motor tore completely down to the bare block. I've been trying to sell most of the stuff like. Rods, pistons, cam ect ect and no luck.
I emailed TSP and they spec me some weisco -3.2 flat top pistons and some callies compstar H-beam rods. They're pretty spendy but I don't want to go cheap, I guess.. Lol

 

I don't think you can run a .020"-.030" head gasket, Most LSx stuff sticks up .006-.008" out of the hole. That would only give a quench of around .012-.024" which is way too tight. Your pistons will hit your heads as metal expands when it's hot. Stick with a GM .052" thick MLS gasket properly sized for your bore, cheap and work great.

 

Hey thanks for the heads up...so it's a .052 gasket from GM?

 

i went to cometic for my head gaskets as i was told by my installer that they are alot bettor.

and pm sent about your head situation

 

GM MLS gaskets are holding up fine for a lot of nitrous and turbo applications.

Mike

 

Cometic gaskets are good, but expensive. If the GM gaskets are working (like Mike says) I would go with them.