CC'in the heads with a Syringe?

[euro911sc]

Do I have to go out and buy some fancy chemist's tool or can I use a syringe to CC my heads? Yes, it will take time and I'll have to count... probably more error prone as well...

Comments?

Have a different cheap way to do this?

Best regards,

Michael

[304065]

I just bought a 50ML glass Burette and a stand from a science supplier on eBay for about $50.

The consequences of getting the calculation wrong are at best lower power in a particular cylinder, because it has a lower compression than the rest, or detonation, because one or more have higher compression than you expect. It wasn't worth trying the cheapo horse syringe and plastic plate kit when the glass Burette and stand were so comparatively inexpensive.

My heads are being rebuilt now, when they come back n a few weeks I'm going to CC them, so I can determine the correct dome volume for my target compression ratio. I'll post detailed pictures of how I do it. . . unless you get there first. . .

[euro911sc]

I had no idea they were so inexpensive. I take it 50 ml is big enough?

I was going to just CC one head, but I guess I'll do them all since it will be easy with everything set up.

best regards,

Michael

[304065]

You can buy a 100ml glass Burette if you prefer. My head volume (2,0 liter) is AROUND 75cc, so I thought that a complete fill with exactly 50ML followed by another fill to approximately half way up the scale would be accurate. Engine builders I have spoken with say if you can get the fill to 1 or 1/2 of a cc it will be accurate enough. But see below: slight changes in head volume make a BIG difference in compression ratio.

[1972_911T]

If you have some nice accurate digital scales that will also work, fill the head with water then pour it off and weigh it. 1cc of water weights 1g. This is easy for me at work as we have scales accurate to 0.001 of a gram

Steve

[tom1394racing]

I'll bet that it would be pretty tough to get all the water (or other fluid) out of the head to get an accurate weight. Water droplets will form on all surfaces and those would be difficult to collect.

There is a reason that folks have been using the burette and cc method for many years.

Has anyone tried to extract the fluid from a 911 head and weigh it?

[euro911sc]

The guy at my head shop (not the smoking kind) said to use an alcohol based fluid like windshield washer fluid as it does not stick to the walls of the head like water does and you can get a much better measurement. You will not get as much curvature at the edge where liquid meets metal. This makes it easier to see that you have filled the whole combustion chamber.

John: hrmnnn... almost a whole point in comp. per 2cc for your example. Now, I really want to be accurate as I don't want to end up much past the 9.8:1 I'm already at from the factory.

Best regards,

Michael

[tom1394racing]

When I did this on my RSR clone, I used windshield washer fluid and motor oil. I got the same result with both.

The biggest challenge I found was getting the air bubble out of the combustion chamber to completely fill the head.