SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: zonahawk on August 11, 2019, 11:44:53 AM

Title: Compression test
Post by: zonahawk on August 11, 2019, 11:44:53 AM

Motor got hot, had a clogged snail and was not timed quite right..

Ran a compression test just now.

Compression test
(Front to back)
Pass side
1. 90 98
2. 120
3. 180 148
4. 98
Driver side
1.  145
2. 190
3. 190
4. 25

Motor has a loud mechanical whine, seems to be on the pass side.. 


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Title: Re: Compression test
Post by: Micky on August 11, 2019, 04:38:27 PM

Doesn’t look good


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Title: Re: Compression test
Post by: zonahawk on August 11, 2019, 08:41:49 PM

Anyone know a ford engine builder in the Midwest?


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Title: Re: Compression test
Post by: mash on it on August 12, 2019, 10:47:13 AM

Follow your compression test with a leak down test especially on the cylinder with 25 psi.

Even just compressed air through the spark plug hole should give you an idea of what the problem is. Valves or rings.

Might just need a valve job, fingers crossed.

Dan'l

Title: Compression test
Post by: zonahawk on September 09, 2019, 09:31:51 PM

Motor ended up having some not so perfect feeling sleeves, #8 felt pitted/warped a bit, and #3 has a touch of scoring I think.  Pulled the motor, going to either rebuild so I know what I have, or buy a 477 stroker out of a mustang that has about an hour on it. 

Wondering besides the obvious parts I'll have to switch over if I decide to swap, are there any gotchas?