TOPIC:

caffcruiser wrote:

Almost done at work, and bored, so I thought this may be pertinant.

"The tools necessary for this measurement job are about the same ones used when "cc’ing" cylinder heads. You’ll need a 100cc burette (a glass cylinder graduated in cubic centimeters, with a valve at the bottom) and stand, available at medical supply houses. A six by six inch piece of flat Plexiglas with a hole in the center is next, and a couple of bottles of isopropyl alcohol (rubbing alcohol). We add a little machinist’s dykem to the alcohol to give it color, making the graduations in the burette easier to read. Another item, which should be on the list, is the all-American handy dandy pocket calculator. Working with figures with six or more digits and keeping track of the decimals can be a pain without one. Accuracy is extremely important: a mere 3cc error is enough to throw your final figure off by a half point, say from 12:l to 11.5:1."

That should answer your question anyhow. Without the proper equipment you won't be able to get within 3 cc's of measurement. Building a high performance motor and being off by 1/2 a point on your compression ratio could be a very costly mistake!

As you see, 3 cc's can be 1/2 point. You can try it yourself, but this test isn't soemthing to base ALL motors on obviously. You think that Kawasaki was real picky about making sure all the chamber volumes on their heads in the 1970's were the correct and identical? Not even close.

This is more of a specified check to see what the compression ratio of YOUR motor will be. I'm using it to find necessary gasket thickness. The gasket thickness in the formula for compression ratio will be my variable. Most people use it to find out the compression ratio, not the gasket thickness. Different strokes I guess.
By the way, I wasn't calling you an idiot by any means. Please don't infer that I was.

Post edited, and I wasnt trying to infer that you were calling me an idiot, its just an expression thats pretty common (maybe just here?)
thanks for the info, I have never actually cc'd a head, never had to. Im using the gasket that came with the Wiseco piston kit, and I havent shaved the head any. I know that the compression wont be high enough to require race gas because this setup has been done allready with great success.

Definitely a good call!

I wish I had a gasket that would work, which is wherein my problem lies.

I have a big bore kit that is a compression that puts me into race gas territory, a combination of parts that furthers that problem, and the need for dropping the compression down low enough to run it all no street gas. My measurement for all of this stuff needs to be extremely precise or I could definitely be talking valves and pistons kissing if you know what I mean.

those factory numbers are more of a baseline im thinking.grinding valves and seats changes the numbers ,also in my experiance the chambers on any given motor will not be exactly the same from one chamber to another either;)

what pistons are you using that puts compression up into the race fuel range?

caffcruiser wrote:

Definitely a good call!

I wish I had a gasket that would work, which is wherein my problem lies.

I have a big bore kit that is a compression that puts me into race gas territory, a combination of parts that furthers that problem, and the need for dropping the compression down low enough to run it all no street gas. My measurement for all of this stuff needs to be extremely precise or I could definitely be talking valves and pistons kissing if you know what I mean.

put some clay in the valve notches on piston and turn motor over by hand.measure the thickness of the clay after turning motor over,this will give you some idea of your clearances.

caffcruiser wrote:

Definitely a good call!

I wish I had a gasket that would work, which is wherein my problem lies.

I have a big bore kit that is a compression that puts me into race gas territory, a combination of parts that furthers that problem, and the need for dropping the compression down low enough to run it all no street gas. My measurement for all of this stuff needs to be extremely precise or I could definitely be talking valves and pistons kissing if you know what I mean.

If you that close with your parts combo,
you need to check with clay and a mic.