120 good compression?
 

I have 71 Chevy 350/350. I did a compression test I got 120 on all the clynder. So is that good or bad? Mileage is 147,000.
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Re: 120 good compression?
 

It depends. Shooting from the hip, I'd say it's low but reasonable for those miles. However, did you have the throttle plates propped open when you did this? If not, it may read low or uneven depending on your technique. And what is the goal here? To diagnose a problem (ie: cylinder not firing, excessive blow-by, leakdown) or what? Usually it is more important to note that the compression doesn't vary more than 10% amongst cylinders, and in that case the details don't matter as much. But if you are trying to figure out something more complicated, then the details of how you did the test do matter.

Re: 120 good compression?
 

I just did one on a mopar motor last week, came up 130 psi through all cyl, ended up being the guage. like said above, more than 10% is what your looking for.

Re: 120 good compression?
 

I wouldnt be worried about it with an old motor sounds like its in descent shape, and definetely a good thing that there all even.

Re: 120 good compression?
 

Nothing wrong with engine other than oil leaks. Which I plan replacing the gaskets this spring.
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Re: 120 good compression?
 

By the way asahi how did you get the name? Is it the beer? They make fantastic stuff.

Re: 120 good compression?
 

It was the name of our beloved Akita. Asahi means morning sun in Japanese. Akita's are excellent protectors and great family dogs. Our Asahi is greatly missed.
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Re: 120 good compression?
 

Akitas are indeed great dogs. My Lab is 12 and I dread the day..........well you know.

Anyways, you never answered if you did the compression test with the throttle blocked open or not? (ignition disabled)

Re: 120 good compression?
 

Sorry throttle was closed
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Re: 120 good compression?
 

do it with the throttle open and it should be higher

Re: 120 good compression?
 

Indeed, just went through this on another thread, and my 130s came up to 170s. There was a bunch of wailing and gnashing of teeth about whether or not you can still use it to compare cylinder-to-cylinder, but for overall wear you need the throttle blocked open.

Someone (HEI?) had a good idea about disabling the ignition, which is a good idea anyway, but more so that you don't forget, put it all back together, and then fire it with the throttle blocked open to WOT.

I'm sure we've all been down the "There's no way I'd forget X" highway.

Re: 120 good compression?
 

Sorry about your loss. Im sure we all wish they could live much longer. I have two 13 year old goldens. Akitas are awesome dogs.