SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: Jasonserb on September 08, 2020, 07:41:46 PM

Title: In addition
Post by: Jasonserb on September 08, 2020, 07:41:46 PM

I'm running a 455 olds bored 30 over
10:1 compression.
I did a compression test in it. The back 2 cylinders are weak compared to The other 6. The front 6 are running between 100 & 110 psi. The back left is @ 75 psi and the back right is @ 95 psi. At an idle I have 40 lbs of oil pressure.

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Title: Re: In addition
Post by: 76Mantra455 on September 08, 2020, 09:10:33 PM

What issue are you having with it? How many hours are on it? Have you done a leak down test on it?

Title: Re: In addition
Post by: Flusher on September 08, 2020, 11:05:24 PM

Also try squirting a shot of oil into the low cylinders, through the spark plug hole, and run the test again.  If it picks up, it indicates rings.

Title: Re: In addition
Post by: Jasonserb on September 09, 2020, 04:00:02 PM

Quote from: 76Mantra455 on September 08, 2020, 09:10:33 PM

What issue are you having with it? How many hours are on it? Have you done a leak down test on it?

It has a knock to it.

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