CC'ing Cyl Head Link/Sticky?

[Williboy]

I can't find the link or sticky that had the process for CC'ing the head and for the calculator to figure the comp ratio. I know the basic process, seal with grease or Vaseline, cover w/ plastic wth 2 holes, measure and fill with tranny fluid or oil.


After 6 months of fouled plugs=valve guide seals=pertronics failure= fuels system overhaul=duraspark install.... I'm finally at a leaking freeze plug on the cyl head. I figured I'd pull the head for access & while I had the head off I'd CC the chamber which I never did when I first rebuilt the motor.

Thanks!!

 

[CNC-Dude]

I would not suggest using oil or tranny fluid to cc the chambers. You need to use something a little more "fluid" such as colored alcohol or parts cleaner liquid such as Varsol. But yes, just seal off with a light coating of grease on both the valve seats and under a clear plastic plate on the deck surface. Your results will be less accurate if the chamber and valves have carbon buildup on them, so clean with a wire brush before you start. And don't forget to put the spark plug back in.

 

[cr_bobcat]

I used Mystery Oil. It's fairly fluid, easy to see, and doesn't corrode anything. I think i just used white lithium grease to seal the valve and the plexi sheet to the head. I also used the same spark plug for each chamber. Just because....

 

[CZLN6]

Howdy all:

Not to hyjack your post williboy but I have a question for CNC-Dude. Why not use auto tranny fluid? That's what we've always used with good results. Just curious on your rationale. Thanks, in advance.

On the stickie Willi, I don't know that there ever was one. Mike (CI) had one on this website. Not sure if it's still available. Sorry.

Adios, David

 

[powerband]

I vote for Marvel Mystery, is fluidy, does gets all over my hands but leaves me with a refreshing minty fragrance ...

I start with a known quantity in a separate container and fill the chamber and subtract what's left . (fer' instance: 60 cc's in a container (2oz) - fill head chamber leaving 10cc's out =/makes for a 50cc chamber)

have fun

 

[CNC-Dude]

Howdy all:

Not to hyjack your post williboy but I have a question for CNC-Dude. Why not use auto tranny fluid?

Its more of an accuracy issue. From being involved professionally with top shelf engine builders for many years, they came to realize that while petroleum based liquids can provide accurate results if certain conditions are met, it is not as stable of a medium to use as other substances. Just consider these petroleum based liquids as being compared to mercury in a thermometer. If you don't have a really closely climate controlled shop environment and the liquid isn't allowed to stabilize to a normal room temp, your results will vary considerably. The same is also true when using plastic burettes instead of glass. For instance, if you go get a quart of tranny fluid out of your shed that is a 100° and pour it into a plastic burette, then you are introducing 2 undesirable variables into the equation, the hot liquid and the thermal expansion of the plastic due to the hot liquid being poured into it. It only takes 1° of temp to see the reaction of mercury in a thermometer, so how much error is introduced by 20°to 30° of temp increase of the fluid and plastic expansion. If your just looking to get a crude baseline then plastic and petroleum based liquids are fine. If you need more accuracy such as determining to the nth degree your DCR for cam selection, then these better alternatives should be chosen or you could make a costly mistake of the wrong camshaft choice if your right on the fence where a few cc's in error isn't realized.