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Old 08-11-2008, 10:51 PM
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CR ? . I know this isnt easy

I have a question that I know cannot be answered properly with amount of info i hve. but, I'm looking for a generality, so to speak.

I posted a question about my 350 awhile back, trying to gain some insight as to the static CR. I cannot find that thread or I would have brought it back to life.

Anyhow, I have this parts store generic rebuilt 350 that came with 416 58 cc heads. The things idles as smooth as silk so the cam is a stock grind, or maybe an rv design. The cranking pressure is 175 psi. Now that i have the cranking pressure is it possible to tell what the static CR is? No, i have no idea about the pistons or anything else.

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Old 08-11-2008, 11:10 PM
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If you knew the deck height, you could possibly figure the compression ratio.
To be honest, I would not worry about it, unless you have to for some racing class reason.
How much timing can the engine take before it knocks? If the engine takes a lot more timing advance than you would think is normal, the compression ratio might be lower than optimum. Likewise, if the engine knocks with "normal" timing, the compression ratio might be high.
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Old 08-11-2008, 11:25 PM
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I've got it at 36 total mechanical all in by 3 grand. No knocks on regular fuel. The reason I'm trying to figure static CR is that I'd like to start rodding it with heads and cam, but with 58 cc chambers already on there I don;t really have any place to go to get some squeeze.




Quote:
Originally Posted by DanielC
If you knew the deck height, you could possibly figure the compression ratio.
To be honest, I would not worry about it, unless you have to for some racing class reason.
How much timing can the engine take before it knocks? If the engine takes a lot more timing advance than you would think is normal, the compression ratio might be lower than optimum. Likewise, if the engine knocks with "normal" timing, the compression ratio might be high.
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Old 08-12-2008, 05:53 AM
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compression

If you had the cam card i could give you a close guess at what the static compression is.

Keith
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Old 08-12-2008, 06:52 AM
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Cr?

DART actually has some iron eagle heads with 49cc chambers, or you could always get the 58's milled down for that extra "SQUEEZE" you speak of. The question is can the rest of your components and your wallet handle that kind of compression and the price you'll pay for the right fuel to run it.
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Old 08-12-2008, 07:57 AM
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Quote:
Originally Posted by eatonde
DART actually has some iron eagle heads with 49cc chambers, or you could always get the 58's milled down for that extra "SQUEEZE" you speak of. The question is can the rest of your components and your wallet handle that kind of compression and the price you'll pay for the right fuel to run it.

Not worried about the fuel, nor am I concerned, at this point, about the rest of the motor. It is a very low miles rebuilt which I am quite certain is of the generic parts store flavor. For now, I just want to bump it a bit. IF i can sell my 78 z28 I am going to build a gnarly 383 to replace this thing. Right now, i just want to muster up about 350 horses with heads and a cam. But, a large cam aint gonna run well at 8:1.
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