Milling 317's down to 58cc
 

Possible and recommendable? I know the deck will be thin for boost though. Here is the deal.

I have 20cc dished Diamond pistons with a stock 6.0L MLS gasket at .054 on a 3.906 bore 4.00 stroke. I am coming up with a 58cc head to get me to 9.75:1 compression where I want to be. I have some really nice CNC and hand finished 317 heads from TPIS though that I want to use with 2.08 and 1.60 valves. Is it possible to get them down that far?

i would look at other options. i think (no actual experience) that if you mill them alot you will have alignment issues. taking out 14 cc's will require quite a bit of milling. maybe someone that has milled them down a bunch can confirm.

Yeah this is a little frustrating but I wont go into details. Basically I need a 58cc head to get my compression where I want it with good flow because I have a KB 2.8L blower on a 383 stroker. Cam is a 225/233 with .585 lift and I want to maximize what I have.

You'll have to mill the 317s close to .085" to get 58cc. Possible, yes. You'll probably compromise your low and mid-lift flow with that much of a mill and possibly get into some intake alignment and valvetrain geometry issues too. I think you could get some decent coin for those 317 heads and put it toward some nicely ported small chamber heads.

Is the engine assembled? If not sell the pistons and get a new set. You'll probably walk away paying the same. I Just sold a set of diamond pistons brand new with a -7cc dish that would have been high 9ish:1 compression with a 3.905 bore and a 4" stroke. I sold them for $400 shipped. So if your pistons are new, you should be able to sell them.

Engine assembled and in the car. Heads are off right now so I am going to put some 241's on go from there for right now. I will buy some 6 bolt TFS 235's this fall and then move onto a LSX next summer.

It's not going to work. That's more like a .098 mill aka a shit ton. You'd have major alignment issues with that kind of mill. You'd also be shrouding the valves even more by the reduction in chamber size. The more you mill the closer the chamber walls come to the sides of the valves.

With 2.08, 1.60s, the milling, and the small bore it would basically kill the heads. Even a TFS 235 is way too large. The minimum recommended bore for those is 4.03 which is far from your 3.90x. I would sell the heads you have and get a nice set of 5.3 heads from TEA. Their stage 1 and 1.5 are a great head for the money. You would also only have to mill those a very small amount to get them to where you want them to be.

What vehicle are you putting this in?

The 235's will go on the LSX 427 next year.

Here is the car.

https://ls1tech.com/forums/forced-in...-now-well.html