We normally use mineral oil to do the CC'ing of chambers. Sometimes the valves don't seal properly then the water can drain past them, where the oil will not. Also on the pistons the mineral oil works better since it won't drain past the rings so fast.

Plus oil doesn't cause rust...

I was thinking of the [edit:] H95. It is 31cc vs 29cc for the H89 which my A14 currently has. It might allow me to use standard grade gasoline, with the H89 I need mid-grade.

The H95 has a lower RPM power band... it is a strong head for power below 4000 RPM.

You going for the h92 instead of the h89?
I would like to do the same but I thought the
h95 was the only swirly high port big valve head
so the 92 is also the same or are there differences
in compression?
I think the cc wouldnt matter here if the pistons
are the same as those on most h89 headed engines.
You are unlikely to go over 10:1 with stock heads.

Same way you did it with the chamber. I have a round disc cut to size for that very reason, you could probably make a circle one out of the cd case, maybe use a soldering iron as a cutter (fumes!).

For increased accuracy you COULD use a variety of syringe sizes but the variables can be a bit of a concern.

Just extract the fluid with the syringe once you've measured the dish.

H75 was 31
GX was 29
H89 was 29

All approximate of course.

Have round port measurements somewhere.

Chris, thanks for your insights.

What CCs have you guys measured for various heads?

Any tips on measuring as-installed piston dish CCs?

CD case and syringe is fine.

Unless it's a serious build (where your comp-ratio is a modification) use a pipette or burette and some thicker clear glass. But to check and confirm it's fine, I use a big syringe and some acrylic to quickly check cc's.

Some also use food dye to help spot bubbles or coloured fluid like kero. The plates I use also have a smaller venting hole (which you can also calculate the volume for assuming you know plate thickness and bore size).

Quote:
Good question. Definitely would be better to use thicker stuff. I had to press down around the edges of the chamber to ensure it was flat, had to be extra careful. 1/4" plexi/lexan might be ideal as it is inflexible (at least for small distances). Before CDs, I used 1/8" plexi because I had some ready to hand.

Also best to use a very thin layer of grease, as it has to be pushed flat so the measurement is not affected. This is where the CD case material flex came into play, the grease thickness was causing it to flex a bit instead of just pushing the grease down. Pushing and rotating the plastic worked well.

Head thickness

B110 GX head: 74 mm, appears original/uncut
B110 closed: Same 74 mm.



H95 [edit] head: 72.5 mm. This is the only A-series head that uses the shorter valves.


I tried this, but the flange is a little different on each head, not accurate method.

B110 closed chamber head: 27 - 29cc

B110 GX head: 28.2 - 29.9 cc (FIA papers say 29.1)

wouldnt the cd cover be a little in acurate beIng so thin and flexable? looks good though