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> 2.0 Head CC, Stock Volume?
Todd Enlund
post Jul 21 2008, 05:31 PM
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I just CCed one of my heads. I got 62cc in both chambers. I thought that stock was 60cc? Does this mean that the buret that I bought is a POS?

By my math, 62cc chambers would give me 9.2:1 with a .040 deck height on a 96x78 mm 2258cc engine... 60cc would give me 9.4:1.

Heads need a rebuild... I'm just trying to figure out where I'm at for a starting point.
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r_towle
post Jul 21 2008, 05:43 PM
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Its quite possible that you have a broken calculator.
with your numbers.
62cc head, 0.04 deck, 96 bore, 78 stroke is 9.1:1
60 cc head, 0.04 deck, 96 bore, 78 stroke is 9.4:1

http://www.aircooled.net/gnrlsite/resource...ninfo/calcs.htm

Rich
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Todd Enlund
post Jul 21 2008, 05:48 PM
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QUOTE(r_towle @ Jul 21 2008, 03:43 PM) *

Its quite possible that you have a broken calculator.
with your numbers.
62cc head, 0.04 deck, 96 bore, 78 stroke is 9.1:1
60 cc head, 0.04 deck, 96 bore, 78 stroke is 9.4:1

http://www.aircooled.net/gnrlsite/resource...ninfo/calcs.htm

Rich

I rounded 9.154 up to 9.2...

I'm still curious about my apparent 62cc chambers, though.
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r_towle
post Jul 21 2008, 05:54 PM
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I will assume that you put in the plug, held the plate down tight with clay.
there are no air bubbles...yes??

I got 58 when I checked my 2.0 liter heads...

Rich
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914Sixer
post Jul 21 2008, 07:14 PM
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Factory Tech Spec book says 58.7-60.2cc. My heads from Hoffman Machine are 62cc in the LE 180 configuration.
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Todd Enlund
post Jul 21 2008, 07:15 PM
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QUOTE(r_towle @ Jul 21 2008, 03:54 PM) *

I will assume that you put in the plug, held the plate down tight with clay.
there are no air bubbles...yes??

I got 58 when I checked my 2.0 liter heads...

Rich

Sealed the plate with vaseline and held it down with pressure from the buret. No air bubbles. I used water the first time, and tried again with 30WT oil... oil was much easier.

I wonder if I used the wrong spark plug...
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r_towle
post Jul 21 2008, 07:30 PM
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I used tranny fluid...easy to see.
Dunno, but I think there was alot of variation from one set to another.

Go for what you want...you can always get the head cut to reduce the chamber and then use base shims to get what you want...

Rich
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Todd Enlund
post Jul 21 2008, 07:55 PM
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QUOTE(r_towle @ Jul 21 2008, 05:30 PM) *

I used tranny fluid...easy to see.
Dunno, but I think there was alot of variation from one set to another.

Go for what you want...you can always get the head cut to reduce the chamber and then use base shims to get what you want...

Rich

I'd be okay if I knew that they were 62cc... but I'm concerned that my buret is "faulty".
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Todd Enlund
post Jul 21 2008, 08:27 PM
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QUOTE(Todd Enlund @ Jul 21 2008, 05:55 PM) *

QUOTE(r_towle @ Jul 21 2008, 05:30 PM) *

I used tranny fluid...easy to see.
Dunno, but I think there was alot of variation from one set to another.

Go for what you want...you can always get the head cut to reduce the chamber and then use base shims to get what you want...

Rich

I'd be okay if I knew that they were 62cc... but I'm concerned that my buret is "faulty".

From the packaging on the buret:

"This Burette Has been caliberated (sic) individually for superior most accuracy."
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Dominic
post Jul 21 2008, 08:45 PM
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QUOTE(Todd Enlund @ Jul 21 2008, 04:31 PM) *

I just CCed one of my heads. I got 62cc in both chambers. I thought that stock was 60cc? Does this mean that the buret that I bought is a POS?

By my math, 62cc chambers would give me 9.2:1 with a .040 deck height on a 96x78 mm 2258cc engine... 60cc would give me 9.4:1.

Heads need a rebuild... I'm just trying to figure out where I'm at for a starting point.



The stroke on the 78mm crank is actually 78.4 mm for a total of 2270cc, so you should have a bit more Compression than you originally figured.
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HAM Inc
post Jul 22 2008, 07:59 AM
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The largest O.E. chamber I can recall measuring came in around 61cc's. Most unatlered OE chambers come in around 58cc's.
Todd if you are getting consistent repeatability, then your method is probably good. I use wintergreen rubbing alcohol. Cheap and cleans up easy. Make sure that you purge the valve of air before measuring.
These chambers were sent from the factory in as cast condition, and they do vary. A 62cc chamber is not tough for me to believe.
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Todd Enlund
post Jul 22 2008, 11:09 AM
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QUOTE(HAM Inc @ Jul 22 2008, 05:59 AM) *

The largest O.E. chamber I can recall measuring came in around 61cc's. Most unatlered OE chambers come in around 58cc's.
Todd if you are getting consistent repeatability, then your method is probably good. I use wintergreen rubbing alcohol. Cheap and cleans up easy. Make sure that you purge the valve of air before measuring.
These chambers were sent from the factory in as cast condition, and they do vary. A 62cc chamber is not tough for me to believe.

Thanks Len. I'll measure one more time to verify...

You'll probably be seeing these heads sooner or later (IMG:style_emoticons/default/biggrin.gif)
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Todd Enlund
post Jul 25 2008, 04:27 PM
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QUOTE(Dominic @ Jul 21 2008, 06:45 PM) *

The stroke on the 78mm crank is actually 78.4 mm for a total of 2270cc, so you should have a bit more Compression than you originally figured.

My crank is actually a 78mm crank, for 2258cc. I dunno who made it, but it's got welded counterweights and I measured it at 78mm.

I checked everything over, and noticed that the plate that I made from acrylic had a burr around the perimeter. I removed the burr, and now I get a reading of 60.2 cc.

Doing a bit of math, a .010" burr on a 94mm cylinder is 1.76 cc, so that is just about right.
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