64cc/70cc74cc what do these mean (help) - Team Camaro Tech
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post #1 of 6 (permalink) Old Aug 5th, 01, 02:21 PM Thread Starter
 
Join Date: May 2001
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Angry

what do these nubers mean how do i find out what head size i have and how do pick heads.

its a 383 stroker 5.7rods .30 over 268 HE.compcam it was a stock 350 lm1 out of a 80z28...
its got 1 3/4 headers.stock carb and intake.

so can someone tell if the stock headers will do for a 0-80mph range 6300redline how lone does it take to port head (shop hours)
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post #2 of 6 (permalink) Old Aug 5th, 01, 09:46 PM
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Those cc's are the combustion chamber volumes. If you get the casting numbers under your valve covers and post them, we could tell you what cc's they are, or go to www.mortec.com , among others.

------------------
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post #3 of 6 (permalink) Old Aug 6th, 01, 04:47 AM
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The 1-3/4" headers will be perfect IMO with a hot 383. I also have a 383 that ocasionally sees a little over 6000 R's with 1-3/4" headers.

The head's volume (measured in cc's) along with the piston type will determine your compression ratio. For example,

I'm using a piston with a 12cc dish and 64cc aluminum heads - my compression ratio is 10.25:1. If you want to run pump gas you probably want to keep your compression ratio at a max of around 10.5:1 with aluminum heads or 9.5:1 with iron heads. You could probably get away with a slightly higher compression ratio and still run premium pump gas, but the numbers I mentioned are generally considered pretty safe.

If you ran a flat top piston with 70 cc heads in a 383, you would get about 10.25:1.

If you ran a flat top piston with a 64 cc head your compression ratio would be about 11.0:1.

A flat top piston with a 76 cc head would get you about 9.75:1.

A 12 cc dished piston with 76cc heads would be about 9.25:1.

Hope this helps.

------------------
68 Camaro, 383 small block with TH350 trans. 12.4's and never trailered.
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post #4 of 6 (permalink) Old Aug 6th, 01, 06:15 AM
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Eric, and everybody else, I hope ya don't mind me pokin my nose in for some clarification on heads and compression.

I realize pistons, gaskets, decks, chambers, valve reliefs, etc. have everything to do with compression and I was going to put 291 camelhumps (64cc) on a 350 with flat tops. From what you're saying I'm looking at 11:1 compression? I'm going to have to rethink my buildup in that case and sell these heads because I want to stay under 10:1.

The last 350 with camelhumps I had used the same setup, except maybe dished pistons (I never had the heads off). It ran fine on 87 and 89 octane, and I had no problem with timing/pinging/knocking, etc. and it ran bada** strong! That was with a mild to mid cam, HEI, 600cfm carb, nothing special at all.

What do you think? Am I missing a crucial link in all this?
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post #5 of 6 (permalink) Old Aug 6th, 01, 02:29 PM
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HwyStarJoe, my post above assumes that engine size remains the same - 383 cubes. With a 350 you are packing a smaller amount of fuel/air into the cylinder head, so your compression ratio will be lower. With flat tops and 64 cc heads on a 350, your compression ratio would be right about 10:1.
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post #6 of 6 (permalink) Old Aug 6th, 01, 05:46 PM
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That's the crucial link I overlooked. 383 vs. 350. My fault. Thanks Eric....
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