transwiz

iTrader: (26)

I was wondering how much you have to mill the heads to make them 66cc
and 64cc? It seems that I have seem several answers to this on the forum.

Are those heads very similar to 243's except the cc's? What is the difference
between 317 and 243's.

96capricemgr

iTrader: (1)

The chamber is the primary difference between the 317 and the 243/799 heads, bigger chamber to keep compression low on the larger displacement truck engines.

Some vendors have reported that the chamber shape alone helps power though after CNC'ing the ports the same and then milling the 317s to the same chamber size the 243 still made more power. Milling can hurt flow and chamber shape affects how the flame travels so don't think that milled 317s are identical to 243s. I know at least one vendor offers the option of having material welded into the 317 chamber to make it just like the 243 after CNC work.

sbf

R u trying to raise the compression with the 317 heads if so don't mill the heads it will hurt flow but u can send them to ai and he can weld up the chambers to lower compression and let him cnc them then u have a 243 head for less than u can buy them for and still have good pvc

transwiz

iTrader: (26)

I have seen posts of guys on here where they mill 317 heads down to get the compression back up to 66cc.The 317 heads are usually really cheap used on here and I see people using them. Thats why I am asking the questions.

batboy

iTrader: (6)

The 317 heads are 71cc. To make them 66cc, you'd have to mill them .030".

transwiz

iTrader: (26)

Are there any problems with the heads mounting to intake if you mill them .030"?
Can you mill them to get them to 64cc without any problems?

batboy

iTrader: (6)

I've seen a lot of people go to .030" with no problems. Above that starts becaming hit or miss with bolt hole alignment. I've heard of people having their machine shop do a technique called angle milling where the intake side is also milled to compensate. But, I'm seeing in your signature that you already have 317 heads milled to 63cc. So, I'm a little puzzled at these questions.

transwiz

iTrader: (26)

I bought the heads that are on my signature from a shop where the original owner left them. He was building a 427 stroker motor. He put a ton of money in them milling,porting and polishing,2.08" fiera intake valves. The guy that ran the shop talked me into using these heads over a stock set of 243's with my 224 cam.
I don't know the specifics of the milling etc, so that's why I am asking all the questions. The car won't pass CA. smog so I am trying to figure out a new head setup.I am pretty low on funds so I am trying to get it right this time.

IllusionalTA

iTrader: (9)

Wonder how much power I'd pick up goin to a 243 with same cr... Especially of milling heads destroys flow... Only major issue I'd be concerned with is intake alignment.. Don't be concerned with the "flow" it's not that big a deal..