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Old 09-18-2019, 07:57 AM   #1
Vanspeed
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Default How many ccs??

How many ccs are stock heads? How many ccs are Snyders 6:1 heads? I have a post saved from a few years ago where Bob Johnston says a 5:5 is 149 and a 6:1 is 137. According to Snyders catalog a 6:1 is 152. Who is right?
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Old 09-18-2019, 10:42 AM   #2
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Default Re: How many ccs??

I have a chart in my book, done by Dave Barker some years ago, showing compression ratios using different bore sizes. It shows 155 for standard bore, 6:1 head. And it shows about 240 cc's for 4.2:1.
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Old 09-18-2019, 12:23 PM   #3
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Default Re: How many ccs??

I bought a head and it measures 125 cc. Just trying to figure out the compression ratio of it.
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Old 09-18-2019, 02:22 PM   #4
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Default Re: How many ccs??

This site has an on line calculator. Just plug in the numbers. http://www.csgnetwork.com/compcalc.html
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Old 09-18-2019, 10:01 PM   #5
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Default Re: How many ccs??

@Vanspeed. Buy Jim's book!
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Old 09-20-2019, 11:32 AM   #6
Jim Brierley
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Default Re: How many ccs??

My chart shows 7.5:1 for 125 cc's, you'll need to add in the gasket volume, I've seen 16.877cc @ .050” thickness and 20.253cc @ .060”. Marco Tahtaras on Ford Barn says 17.474cc. I’ve been using 20cc, a nice round figure. 145 is about 6.5:1
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Old 09-21-2019, 09:36 AM   #7
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Default Re: How many ccs??

Wouldn't any piston pop up negate the the added cc's for the gasket thickness? For example if the block had been decked or other reasons.
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Old 09-21-2019, 09:47 AM   #8
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Default Re: How many ccs??

Good point redmodelt! Yes, piston pop-up means fewer cc's of combustion chamber volume. It's normally about .015" but should be measured. At least .040" clearance should be maintained between the piston and the head as rods will stretch at high RPM's.
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Old 09-23-2019, 10:42 AM   #9
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Default Re: How many ccs??

Thanks for the info guys. I have yet to pull the stock head to measure piston pop up if any.
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