Re: Head Bowl Size
[Re: JohnRR]
#816063
09/27/10 06:45 PM
09/27/10 06:45 PM
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Junky
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Quote:
If the heads have not been decked a lot go with 90cc and you can't go wrong.
Wow, 90. Thanks John.
Help me estimate.
346 Heads 90cc
Pistons about 0.020 (left side) to 0.025 (right side) in the hole.
Heads were milled 0.030
4.25 bore size.
Steel shim head gaskets.
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Re: Head Bowl Size
[Re: Junky]
#816064
09/27/10 08:50 PM
09/27/10 08:50 PM
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RapidRobert
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fyi you are referring to chamber size as opposed to bowl cc's or port cc's. Here is a very user friendly static CR calculator that will most likely (satisfactorily) ans your Q in seconds. reportedly if you want an accurate DCR you do not want to use their next calculation for that but there's a much more accurate one out there for that to use so dont plug in cam specs just your deck height/cc's etc. http://kb-silvolite.com/calc.php?
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Re: Head Bowl Size
[Re: RapidRobert]
#816065
09/27/10 09:10 PM
09/27/10 09:10 PM
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Quote:
fyi you are referring to chamber size as opposed to bowl cc's or port cc's. Here is a very user friendly static CR calculator that will most likely (satisfactorily) ans your Q in seconds. reportedly if you want an accurate DCR you do not want to use their next calculation for that but there's a much more accurate one out there for that to use so dont plug in cam specs just your deck height/cc's etc. http://kb-silvolite.com/calc.php?
Thank you for your help. However, I have no clue what data to enter.
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Re: Head Bowl Size
[Re: Junky]
#816066
09/27/10 09:14 PM
09/27/10 09:14 PM
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Lincoln Nebraska
RapidRobert
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everything in the top section. EDIT piston vol is the cc's of the valve reliefs or the dome cc's whichever you have. they changed the format some as they used to prompt you to enter the cc's as a negative # if it is a dome but iirc you have flat tops or valve reliefs so you're good, just lookup the spec for your pistons and enter that figure w no neg or positive notation and let it do the work from there
Last edited by RapidRobert; 09/27/10 09:21 PM.
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Re: Head Bowl Size
[Re: Junky]
#816068
09/27/10 11:29 PM
09/27/10 11:29 PM
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RapidRobert
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head vol that'd be slightly less than 90 though it'd be good to CC a chamber. piston head vol would be zero since you have flattops w no reliefs. gasket bore not sure, maybe 4.350" but I hate to guess as we're trying to be precise, maybe someone else knows
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Re: Head Bowl Size
[Re: RapidRobert]
#816069
09/28/10 02:17 AM
09/28/10 02:17 AM
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Junky
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Thanks for your help RapidRobert The static compression ratio comes out to be 6.983 So, what is "static" compression ratio? 6.983 compression? I thought it would be closer to 8.5 
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Re: Head Bowl Size
[Re: Junky]
#816071
09/28/10 10:09 AM
09/28/10 10:09 AM
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JohnRR
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Quote:
I don't know what to enter for:
Cylinder Head Volume (cc) [Is that 90cc? If so, I milled them 0.030]
Piston Head Volume (cc) ?
Gasket Bore (in.) ?
My pistons are flat tops, no valve reliefs.
Here's a picture of what I've entered so far.
if you took off .030 then 85cc is a safe number as I have seen these open chamber heads anywhere from 90-92cc. Steel shim gasket is going to be roughly 4.410 bore size , .021 thick .
I use the calculator at Diamondracing.net
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Re: Head Bowl Size
[Re: Junky]
#816072
09/28/10 10:14 AM
09/28/10 10:14 AM
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JohnRR
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Quote:
Quote:
If the heads have not been decked a lot go with 90cc and you can't go wrong.
Wow, 90. Thanks John.
Help me estimate.
346 Heads 90cc
Pistons about 0.020 (left side) to 0.025 (right side) in the hole.
Heads were milled 0.030
4.25 bore size.
Steel shim head gaskets.
here's the specs I used ....
heads 84cc
piston to deck i split it at .0225
4.250 bore
4.410 gasket bore
gasket thickness .021
top ring .300 below piston surface
block height 9.98
stroke 3.375
rod 6.358
comes out to 9.2 , 85cc head it's 9.11
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Re: Head Bowl Size
[Re: JohnRR]
#816073
09/28/10 10:52 AM
09/28/10 10:52 AM
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Junky
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Quote:
Quote:
Quote:
If the heads have not been decked a lot go with 90cc and you can't go wrong.
Wow, 90. Thanks John.
Help me estimate.
346 Heads 90cc
Pistons about 0.020 (left side) to 0.025 (right side) in the hole.
Heads were milled 0.030
4.25 bore size.
Steel shim head gaskets.
here's the specs I used ....
heads 84cc
piston to deck i split it at .0225
4.250 bore
4.410 gasket bore
gasket thickness .021
top ring .300 below piston surface
block height 9.98
stroke 3.375
rod 6.358
comes out to 9.2 , 85cc head it's 9.11
Thank ya, thank ya. That's not too bad.
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Re: Head Bowl Size
[Re: Junky]
#816075
09/28/10 12:31 PM
09/28/10 12:31 PM
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JohnRR
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Quote:
I forgot to mention something. The engine in question is out of a '71 Newport, a 383 four barrel, dual exhaust rated at 8.5 to 1 according to specifications.
Didn't know if that helps.
shouldn't make a difference assuming your piston spec in the hole is correct ? was it rebuilt, if so what piston did you use ?
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Re: Head Bowl Size
[Re: Junky]
#816077
09/28/10 04:25 PM
09/28/10 04:25 PM
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JohnRR
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Quote:
When I had the heads off it looked like the pistons were stock. I left them as is. Engine runs good and doesn't smoke. I don't have much for tools. Took a feeler gauge and a straight edge to measure how far they were down in the hole when they were all the way up. 0.020 on one side, 0.025 on the other, snug.
Thanks for your time, John.
Flat tops or a dish ? 2bbl engine ?
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