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Old 07-06-2015, 09:41 PM   #11
VettezukiVettezuki is offline
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PS Adam's Vette is still the fastest car I've been from a roll. It's pretty ridiculous. My guess, and it is a guess, is well over 500 to the wheels and whatever his weight is, plus fairly short gearing AIR. Same as my Vette though, I don't think it'd be particularly fast in teh 1/4 because the suspension is all wrong to launch worth a shit. It'd be like 12 @ 130 or something stupid like that.
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Old 07-07-2015, 01:37 PM   #12
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Thanks? Haha.

Compression has always been this low. Even before the motor was first fired. I've often been cautioned by gear heads about it. But I have low compression, and fatty NA intended overlap. I really need a blower cam... and by B Day is 21 days away! ...just sayin

Engine makes power, doesn't burn oil, and the compression is consistent, it's fine.
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Old 07-07-2015, 05:18 PM   #13
Shaolin CraneShaolin Crane is offline
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Quote:
Originally Posted by enkeivette View Post
Thanks? Haha.

Compression has always been this low. Even before the motor was first fired. I've often been cautioned by gear heads about it. But I have low compression, and fatty NA intended overlap. I really need a blower cam... and by B Day is 21 days away! ...just sayin

Engine makes power, doesn't burn oil, and the compression is consistent, it's fine.
How did you test cranking compression before you fired it?
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Old 07-07-2015, 09:44 PM   #14
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What's your static compression, piston to head clearance and cam specs? The Chevelle has decent overlap with 246 duration at .050 and a 110 LSA.
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Old 07-08-2015, 06:35 AM   #15
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How did you test cranking compression before you fired it?
Put the compression tool in the spark plug hole and ran the starter motor before I ever first fired it.

Compression is like 9:1, cam is 110 246 248? Or something...
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Old 07-08-2015, 06:39 AM   #16
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Piston to head, don't remember. I think my pistons are like .02 down and the HG is .05. So prob .07. Some people cry about quench but the thicker HG/ lower CR was more important to me. AFR and speed talk tells me quench is of little consequence when the boost does the swirling.
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Old 07-08-2015, 08:14 AM   #17
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.070 isn't great but the Cobra is at .053 if I remember correctly. Even with the old 302 setup which had a compression ratio around 8.7-8.8 and a cam that had 110 LSA with 220 @ .050 it still cranked 150psi. Something isn't right. Does your car run good, sure. Could it run better, most likely.
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Old 07-08-2015, 08:15 AM   #18
Shaolin CraneShaolin Crane is offline
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Quote:
Originally Posted by enkeivette View Post
Put the compression tool in the spark plug hole and ran the starter motor before I ever first fired it.

Compression is like 9:1, cam is 110 246 248? Or something...
So before the engine was ever broken in? Not sure that would be an accurate compression test.
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Old 07-08-2015, 07:05 PM   #19
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Quote:
Originally Posted by 94cobra69ss396 View Post
.070 isn't great but the Cobra is at .053 if I remember correctly. Even with the old 302 setup which had a compression ratio around 8.7-8.8 and a cam that had 110 LSA with 220 @ .050 it still cranked 150psi. Something isn't right. Does your car run good, sure. Could it run better, most likely.
Ive been through 4 HG replacements, probably 10 intake manifold replacements, and 2 sets of piston rings. What could possibly account for a uniform loss of compression in all cylinders, that does not cause oil consumption, loss of mpg, or at least a significant loss of power, while persisting through all of those changes?

Quench alone shouldn't change a compression reading. 9:1 with a 110 should produce the same measurement no matter how that air is swirling around in there.

Guy, yes, compression test was the same before and after break in.
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Old 07-08-2015, 10:31 PM   #20
Shaolin CraneShaolin Crane is offline
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Quote:
Originally Posted by enkeivette View Post
Ive been through 4 HG replacements, probably 10 intake manifold replacements, and 2 sets of piston rings. What could possibly account for a uniform loss of compression in all cylinders, that does not cause oil consumption, loss of mpg, or at least a significant loss of power, while persisting through all of those changes?

Quench alone shouldn't change a compression reading. 9:1 with a 110 should produce the same measurement no matter how that air is swirling around in there.

Guy, yes, compression test was the same before and after break in.
Ring gap, pushrod length, rockers, lifters, basically anything valve train related could cause uniform compression issues if something was not installed right or a wrong part was used. Not uncommon for people to think they have compression loss only to find out they have way too much preload on the valve train.

I don't have any one thing I can say it would be, however I do know that 9:1 should make a minimum of 130psi with a 110 lobe center. Are you positive you calculated the compression properly? What df the heads CC out to?
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