427TTA4

iTrader: (1)

I'm trying to do the correct math here but I'm in need of some expert advice. Stock Ls1 bottom end,stock GM gaskets, milled 317 down .006= 1cc so let's say milled .030= 5cc , 5cc - 71.06 = 66.06 cc size , with a 238/242 .605/.610 112lsa. "ms3 cam". Will milling the 317 that much put me on the red zone or what's the max mill I can go on the stock Ls1 pistons having ptv in mind. I don't mind being in the danger zone, the end I will clay the block to be safe. I got the 317 heads for free so 243s are out the question. Thanks !!

PREDATOR-Z

It will not fit. .006 yes but .030 mill no way..

Sales3@Texas-Speed

iTrader: (2)

^^^ Agreed. If you're looking for a nice bump in compression just pick up a set of 243 heads or even stock LS1 heads. If you would like a CNC ported version give me a call and I can walk you through your options.

Lonnie

yonerhottlt1

iTrader: (21)

Aren't stock LS1 heads 66cc?!

Sales3@Texas-Speed

iTrader: (2)

Yes they are but they still offer an increase in compression over the 71cc 317 heads.

Lonnie

427TTA4

iTrader: (1)

Well this sucks lol so basically theirs no way getting the heads down to 66.67 cc to ls1 cc specs with this cam right?

Rise of the Phoenix

iTrader: (27)

Not unless you want to flycut. If you want to flycut, then I would go for more of a mill and shoot for 12:1 or 11.5:1 compression.

yonerhottlt1

iTrader: (21)

I understand that. But my point is there are plenty of ppl running the MS3 with the stock 241 heads, which are 66cc. So why wouldn't it work with 317's at 66cc?! He'll still be gaining compression and the 317's flow better than 241's anyways.

Sales3@Texas-Speed

iTrader: (2)

The MS3 cam is a max effort cam. If you try to mill (shaving the bottom of the heads down)on a set of 317's to 66cc it lowers the valves closer to the piston tops and therefore decreases PTC clearance since they start at 71cc. Both the 241's and 317's have the same PTV clearance stock vs stock. The valves are at the same height in the combustion chamber. The 241's just start at 64cc so it does not need any material removed. I hope this helps.

Lonnie

yonerhottlt1

iTrader: (21)

Aaaaaahh...see now that makes more sense. I'm guessing this same rule applies for all of the stock cathedral port heads?!

tuckin22

dang guess I have to get rid of my 317's as well...

PREDATOR-Z

There is another option besides milling.
You send the heads for porting and welding the chambers to desired cc. So valve drop remains unchanged but chamber gets smaller and thus increases compression. AI does a really nice job at that.
I experienced that fist hand on a set of heads I had on for a supercharged setup. When I went NA, I needed smaller chambers. Your end product are aset of cnc ported heads with small chambers and all the benefits of the 243/799 port design.

tuckin22

^hmm interesting idea on that... but would the cost be more effective than getting the correct size heads?

TheLSBeast

How much for the welding on the chambers?