Milling

[hasa68mustang]

I decided on this motor I will stick with N/A and was wanting to know what I can safely mill the head to (how many cc's? may have been milled before multiple times) I am unsure of what my goal of compression is, I would like higher.... any suggestions? I woudl try to be more specific but I am off to FINISH painting my car...

 

[MustangSix]

I recommend you shoot for no more than 9.5:1 and then only if you want to use premium fuel. 9.0:1 would allow you to use regualr and midgrade for the most part.

 

[Anonymous]

You may have to cc the head when you pull it to be sure of the size of the chambers.

You could also have a late model "big log" head milled and ready to go on the same day you pull yours.

 

[hasa68mustang]

well right now I am using a "bigger log" head, and its in the garage being painted... I ran out of thinner so I have to run out tomorrow to get some... but yes back to the topic.... how do you calculate compression ratio? or does anyone know what cc it would come out to so I could just tell the machinist? I guess I am going for the 9.0 cr. what about the head gasket? so ya... if I dont make sense I am tired and have been working and painting all day (with a mask) Thanks, Tommy

 

[Anonymous]

To calculate cc, use an old CD as a cover for the combustion chamber (that's why AOL sends so many out in the mail!). Smear a layer of grease around the chamber to seal the CD to it.

Use a syringe to measure any liquid, I use ATF fluid. Sometimes pharmacies give them away for free to measure childrens cough syrup and such. The nipple on the end is sized so they won't hold a needle.

To check your deck height you need one clean piston, a straightedge, and some feeler gauges. Bring the piston to TDC and measure between the straightedge across the cylinder and the piston top with a feeler gauge.

Plug in the numbers:

http://www.turbofast.com.au/Tfcomp.html

 

[Hot 6t Falcon]

I REALLY LIKE Linc's idea to use an old CD. That's a really GOOD use of all of those disks AOL sends out. He's right that it would be best for you to cc your head, so you are not just poking around in the dark.

Here's a different web site to play with for figuring your compression.
http://falconperformance.sundog.net/compcalculator.asp

It'll work pretty much the same as Lincs, but most of the numbers are preset for a 200. You'll need to change the gasket thickness to anywhere from .044 to .050, depending on the headgasket you use. The .025 is good for a stock steel shim gasket (hard to find)

Also, if you use Linc compression calculator, be sure to add 7 cc to the combustion chamber to compensate for the dish in the piston (if you've got a CA smog motor add 14 cc).

I'd suggest that you got to Falcon Performance to just play with the numbers. See how the head gasket thickness changes compresson. A Victor 3910VC is .044 compressed and a Fel-Pro is .050 compressed.

Another FYI is that a mill of .010 is equal to a reduction of 2+ cc's. As you get down to only milling the "D" shape of the combustion chamber the cc reduction will be even less. Keep in mind that you need to mill off .020 just to compesate for the new-styled head gasket.

The horsepower rating on my site is basiically just for comparison as to how changes affect the engine's output.

 

[Anonymous]

Mines been milled .080!

Thats on a 78 big log head....compression ratio is somewhere between 10.5:1-11.25:1

Doug

 

[wsa111]

My 80 head is milled .080 & I have about 9.5 compression,

My cranking compression with my 264 FSPP camshaft is 175#.

I really wanted 190-195# cranking compression.

This will take flat top pistons & a lot more duration on the camshaft to keep the cranking compression under 200 #s.

This is the case with mustang geezer. His combination is ideal if you want to get the last bit of power out of the log head.

Yes you will need a higher stall speed converter if you have the c-4 trans.

As I said this is the ultimate. William