74u

iTrader: (9)

I'm about to pull the trigger on a new LS3 block. Per Summit the 4.065 finished bore is good to go and I can build as is w/4.065 pistons. True, or False?

Regardless what I'm told I will have everything checked/verified prior to assembly...mostly asking because I want to buy pistons at the same time (cost savings) but don't want to buy 4.065's only to find out the bores are junk and need redone at 4.070.

What has been your experience with this block?

EDIT: Will be a 416 stroker in a street car...maybe 600 rwhp max
EDIT 2: I will likely be buying from a site sponsor...just explaining my conversation with Summit

Jimbo1367

Realistically. it won't be 600RWHP and a streetcar. Plan on going over bored (honed). You NEED to bore/hone cylinders to fit each piston. I'd just get a sponsor (TSP) to supply the complete engine or short block and top it off the way you want.

74u

iTrader: (9)

600whp is total with a 75-100 dry shot...I'm thinking 500-525 NA should be realistic for a 416 with really good heads, 11:x compression, and custom grind 239/246 cam through an M6.

My last combo was a TSP 404 and used 1qt/1000 miles from day one. After a leak down test showed tons of air going past the rings I had it tore down (14K miles on motor) by another site sponsor who found very little appreciable wear but still it had .0085-.009" piston to wall clearance.

Not ******* TSP, just making the point there are no guarantees regardless who built it.

I'm reusing my crank, and rods from my 404 and decided to buy 4.070" pistons due to availability and allowing some room for fitting to the bore.

Again, not attacking TSP...I just spent a ton of money on parts with them. I think they are a top shelf vendor. I just want to be involved in this build and hope like hell it comes out right.

Jimbo1367

You might want to research Mahl's low expansion forged pistons and ring set. I've heard good things about them. Not sure if they are a option with NOS though.

BLINGOLE

iTrader: (5)

Idk I heard the 6.0 iron summit blocks had some crap machining. But that is what stopped me from buying one awhile back.

98TransAmWs-6

iTrader: (11)

Mine from Summit does not appear to have crap machining.

BOLO

iTrader: (40)

I would still have a machine shop and/or your engine builder go through the block before just slapping the rotating assemblies in there regardless.IMO.

98TransAmWs-6

iTrader: (11)

That is the smart thing to do regardless if it is brand new from GM with no additional machining. For my build I am not assembling it myself anyhow, Tick Performance is so that will be done.

Jimbo1367

For some reason I think TDK engines machines Summits 6.0L blocks. Hopefully someone from Summit can chime in.

FLYZNTN

What's Tick building for you?

98TransAmWs-6

iTrader: (11)

A 421 iron block. I have everything I need I just need to drop it off at Tick now.

FLYZNTN

4.030 x 4.125 I'm assuming.

Did you pick up your own rotating assembly?

98TransAmWs-6

iTrader: (11)

Yes and yes. K1 stroker rods, K1 4.125 crank, and Wiseco +3 cc domed 4.03 bore pistons with upgraded pins. I don't want to jack the OPs thread so if you want more info PM me and I'll share plus send you the link to my build thread.

FLYZNTN

Cool. Sorry OP.