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#1
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How many cc`s
How many cc`s on average does the 452 combustion chamber
hold ? From the factory . as in un cut. With stock valve sizes. And What amount on average would it change by installing 2.140 and 1.810 valves? Thanks |
#2
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I'm pretty sure that they're typically 88cc.
As for valve change effect...I have no idea. I can't imagine the change to a bigger valve makeing more than a cc or 2 difference either way, if any change at all. |
#3
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My 452s were 88ccs + .5cc max, -0.0cc. Changing valve sizes will not make a measureable difference.
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#4
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I ccccccccc`s
Thanks guys
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#5
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My engine decoding info shows a 4006 452 76-78 400/440 head @ 81.5 cc with 2.08/1.74 valves
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#6
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Head cc's
452's typically come in anywhere 85 to 90 cc's. depending on wear. Factors which adjust the volume of the chamber cc's are valve depth(sunk valves) or different design underheads( tuliped or nailhead/flat). If installing big valves 2.14/1.81, ensure to select a valve head design that is as flat on the bottom as possible(ferrea??) and that your machinist understands your rocker requirements ie; adjustable or non.
Either way, try not to "sink" the valve in the chambers by maintaining a high seat profile, and maintain the valve tip height within the factory spec(2.095-2.135"?? I Forget, I'll look it up later if interested), this is especially important if not using adjustable rockers so as to maintain correct lifter plunger preload. If done properly, it's not uncommon to take a "stock" 88cc 452, rebuild it with big valves (2.14/1.81), and when finished, having only done a "cleanup surfacing", wind up with an 82 cc head. It can be expensive laborwise though, as with everything, time is money. Good luck with 'yer stuff!! |
#7
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Every set of 452s I have checked had combustion chambers in the range of 88 - 89 ccs. And - each head was very consistant. Also, just replacing the valves with a larger valve will have no significant effect on combustion chamber volume... no where NEAR 6 ccs - more like a quarter to a half cc. This is an insignificant change.
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#8
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Head cc
Hey doug, thats cause you're usually checking used heads worn from service. Sorry to correct you, but,...each .010" that a stock 2.08" valve sinks into the chamber, and conversely the valve tip protrudes out on the other side, you add .55 cc. Each 1.74" exhaust per .010" sink adds .4cc. Go and measure your valve heights on the heads you're cc'ing keeping in mind that the "FACTORY" height was at the 2.095" range. Most of yours I'll bet are up at the 2.140" mark or higher from service. That would mean they have/are "UP" in the chamber .030" to .040", from where we would place the newer "big valves" on a blueprint head build. The math says that would minus 3 - 4 cc's right there. Now to get the rest, we simply pick valves that are flat bottomed unlike the stock dishs( 1 to 1.5 cc's), then surface 'em .005 - .010", get my point.
Valve shape does make a difference C.R. when you pay attention to it as well as heights. |
#9
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##
Those sound like pretty good #`s.
Thanks |
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