How many thousands of an inch per CC?

[838]

When calculating cylinder head volume, how many thousandths of an inch equate to a 1cc increase in compression?

Thanks

[Ohio HD]

"Standard" Twin Cam heads in "about" 1cc per 0.007". You really need to measure the volume of the chamber, cut, measure, repeat. 

[FSG]

[Norton Commando]

You really need to measure the volume of the chamber, cut, measure, repeat.

Yep. One cc (cubic centimeter) = 0.06102374 in^3 (cubic inches). 

[Don D]

Ymmv, the acr heads have the added slot. .0067 is ballpark. Not something to count on. Invest in measuring tools and know for sure. The balance can be very different between heads and that requires uneven amounts of cut to get them equal.

[kd]

mine cc'd about .005" different from each other when decked to even volumes when setting the compression.  FYI, my MVA heads, .041 and .051 to get the cc's right for 11.3 with .030 gaskets.  Measure and take small cuts and remeasure to sneak up on your target volume.

[prodrag1320]

don't go by any "formula".cc,mill,cc some more & mill some more.get the tools to do it right or find someone who can

[sfmichael]

don't go by any "formula".cc,mill,cc some more & mill some more.get the tools to do it right or find someone who can

Ymmv, the acr heads have the added slot. .0067 is ballpark. Not something to count on. Invest in measuring tools and know for sure. The balance can be very different between heads and that requires uneven amounts of cut to get them equal.

2 guys that know

as Ohio said .007 is usually darn close

[Hillside Motorcycle]

Thumb of rule is .006", except when sliding down past the radius chamber on a CVO head.
Cut, cc. cut, cc.

[rigidthumper]

Cheap 100 ml, .2cc graduated burette tubes are available for 25-30 dollars, good enough for what you are doing.  Use the cheapest rubbing alcohol the pharmacy has, put a few drops of food coloring from the grocery store in the bottle, mix it up and pour.

[sfmichael]

Cheap 100 ml, .2cc graduated burette tubes are available for 25-30 dollars, good enough for what you are doing.  Use the cheapest rubbing alcohol the pharmacy has, put a few drops of food coloring from the grocery store in the bottle, mix it up and pour.

   

windshield washer solvent works okay too and you probably have some laying around

[PoorUB]

/quote]



The blue tint helps see the liquid.

[Ohio HD]

Rubbing alcohol doesn't have bubbles in it. Washer fluid can acquire bubbles when poured. Rubbing alcohol also isn't going to start any micro corrosion on valves.

[PoorUB]

Rubbing alcohol doesn't have bubbles in it. Washer fluid can acquire bubbles when poured. Rubbing alcohol also isn't going to start any micro corrosion on valves.

Never had any problems with bubbles and I blow off the head well and give it a squirt of WD40 when done.

[98fxstc]

Rubbing alcohol doesn't have bubbles in it. Washer fluid can acquire bubbles when poured. Rubbing alcohol also isn't going to start any micro corrosion on valves.

[Don D]

Fill with a nalgene bottle, no bubbles

[Hillside Motorcycle]

Alcohol does not have any surface tension, and readily flows.
We put a few drops of red dye in the bottle.
A plastic 100cc burret will not withstand alcohol.
We use glass units here.

[Buglet]

   No bubbles here.

[Don D]

Guys should be careful with the cheap plastic burettes. Check the certification, glass is the only one that can have a class A certification. Many of the uncertified imports are very far off.

[thumper 823]

TRhere is ONLY one way to measure this and it is A PIA .
But you do get repeatable  results [attach=0]