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ganymede 05-29-2012 05:39 PM

CC-ing chambers with clay
Is clay accurate?...dropped into a marked beaker of course.

LATECH 05-29-2012 06:53 PM

It can be accurate , but it is better for checking valve clearnce.
Just CC your heads with water by covering the chamber with a stiff piece of plexiglass that has a fill hole drilled in it. I used an old CD ,it was a clear one that was used as a spacer or in a pack of new CD-rw that I bought.
I bought a Beret from Online science mall on e bay for like 25 bucks.
It was easy to check, and accurate once I had the right stuff.
Some guys mix something with the water to help break surface tension, so it gives an absolutley perfect reading.I didnt use anything but water. I just needed to know I was real close.Got both heads shaved and ended up at 82 CC s on each one.I checked all 8 to be sure they were all even before i had them milled, just to keep the record straight.

cobalt327 05-29-2012 06:53 PM


Originally Posted by ganymede
Is clay accurate?...dropped into a marked beaker of course.

Sure, you could measure the volume by displacing the water in a beaker if it's accurately graduated. The trick is to get the clay level w/the surface of the deck- even a small amount over or under will skew the results.

Any reason you don't want to use the more traditional method of colored water/isopropyl alky mix, a piece of clear plexiglass or a CD w/the plating scraped off, a dab of vaselene, and a 10cc syringe from the vet or pharmacy?

ganymede 05-29-2012 08:47 PM

ha, ha. Job is this weekend. I don't have time to order a burette. Should be easy to level the clay with a machinist straight-edge. Going to try .015 rubber coated steel shims.

cdminter59 05-30-2012 11:20 PM

CC-ing heads
I have never in my life heard of anyone cc-ing a head with clay! I am 60 years old.

ganymede 05-31-2012 02:21 PM

Thanx for input everyone. I bought non-hardening modeling clay and a kitchen beaker at WalMart & Hobby Lobby for $8 today(clay was 30% off). The beaker is graduated in 2 ml. I believe it can just as accurate if I do it right. I know several hotrodders have done it. Wipe chamber with silicone lube so it doesn't stick. Lightly pound it in. Level it and drop in beaker. If it comes close to 63 to 64 cc it should be accurate.

cobalt327 05-31-2012 04:44 PM

It will be accurate to maybe plus or minus a cc or so. I wouldn't use it to equalize chamber volumes- you need better accuracy for that. But for getting an estimate for figuring compression ratios, it's fine.

I don't know if you were going to smash the clay down into the beaker to measure the volume, but the easier way is to add a known volume of water to the beaker- enough to cover the clay- and then ease the clay down into the beaker and see the lever the water rises to. That level, minus the starting amount of water, will be the chamber volume in cc.

spinn 05-31-2012 07:33 PM

Emergency rooms will dispense a 10cc graduated syringe for free.

A CD jacket clear top with a small hole works fine.

ap72 05-31-2012 10:11 PM

i use a 10cc syringe but it takes a while and its a pita to get right as you have to keep refilling it.

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