Compression Test Results

arbita1 · arbita1's Garage

I have a leaky engine and am planning on pulling it to address the leaks. Also I want to install 964 cams. The engine has 205,000 miles on it and I figured it's time for a rebuild as well. I'm trying to decide how much of a rebuild is required. I did a compression test today. See results below.

I'm at elevation 679 ft so my actuals are around 141psi for the high and 137psi for the low if I factor that in. All are within 97% of each other. Any thoughts on my results?

Also I think my spark plugs look pretty good.

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Jdub · 01-23-2016, 09:25 AM

Congrats on owning another amazing 3.0 SC engine. I suppose a rebuild would give you peace of mind for the lower stud row, but beyond that (your improvements aside) what I am seeing looks pretty good.

Best of luck on whatever you decide!

GMR911 · 01-25-2016, 04:08 PM

My 78 3l ROW motor tested 155,160,160,160,160,165. It had about 90.000 mi when I did it

patz · 01-25-2016, 07:31 PM

Good stuff, stop worrying.

snbush67 · snbush67's Garage

Congrats on the great motor.

I have a question...did the leaks start recently and have you recently changed to synthetic oil?

arbita1 · arbita1's Garage

Thanks.

Quote:

Originally Posted by snbush67

Congrats on the great motor.

I have a question...did the leaks start recently and have you recently changed to synthetic oil?

No it always had a leaky engine. However it's gotten far worse in the last few years.

I started using synthetic when I first bought the car and have since switched to Valvoline Racing. No change in leak.

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snbush67 · snbush67's Garage

Thanks Matt, I am all for pulling the motor to reseal leaking areas and doing a clean up etc. But if its just the oil return tubes or the engine mounted cooler than you might just be better off doing those from under the car.

My experience has been that once you pull the motor cash starts flying out of your wallet. Its an addiction. I pulled my motor to repair a cam seal leak and it turned into a monster.

scarceller · scarceller's Garage

Those compression results are very good for a motor with that many miles! The color of the plugs is also fine. I'd say it's healthy. Just fix the leaks

sballard · 01-26-2016, 11:51 AM

My '72 used to leak a lot of oil. I pulled the engine and replaced the oil cooler seals and I torqued the rocker shaft bolts to the recommended values. Hasn't leaked a drop since. From the appearance of the engine, I think that most of the oil was leaking from the rocker shafts. Definitely worth doing.