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Compression Test Results

Old Aug 15, 2008 | 06:46 PM
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Default Compression Test Results

71 350ci motor

I was given a 350ci motor that had been sitting for a year. It was told it had 375hp. I changed the oil and completed a compression test.

1 3 5 7
140 150 135 150

2 4 6 8
160 155 130 130


The motor is sitting in the frame with the transmission attached.

Any advice on what to do next or are the numbers ok. Thanks.
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Old Aug 15, 2008 | 08:12 PM
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That engine DOES NOT have 375hp. It is a low compression engine with some worn piston rings. You probably will need to rebuild it if you want to make anything out of it. My guess is that it is a stock SB 350 with 8.5:1 compression--rated at 270hp in '71 and rated at 220hp in '72.
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Old Aug 15, 2008 | 08:28 PM
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Originally Posted by bene
71 350ci motor

I was given a 350ci motor that had been sitting for a year. It was told it had 375hp. I changed the oil and completed a compression test.

1 3 5 7
140 150 135 150

2 4 6 8
160 155 130 130


The motor is sitting in the frame with the transmission attached.

Any advice on what to do next or are the numbers ok. Thanks.
Do a leak down test on all cylinders, this will give you a little more info on the condition of this motor.
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Old Aug 15, 2008 | 09:09 PM
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Thank you I will get a tester and check the leakage.
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Old Aug 16, 2008 | 04:24 AM
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FYI, my 350 with 8.6:1 compression did a cold compression test with all cilinders between 155 and 160 psi.
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Old Aug 16, 2008 | 06:01 AM
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My stock '73 runs about 170-175 lbs after 3 cranks.
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Old Aug 16, 2008 | 09:25 AM
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i don't see the point of a leak down test.
if u r in need of a free motor, put it in and drive it.
if u want to rebuld it now rather than later, that makes sense too.
in '75 i put a $50 motor in my 61 and drove it 10,000 miles. never did any tests, why bother,
i just wanted to drive my 61
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