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Compression readings 

 

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 Post subject: Compression readings
Posted: Fri Nov 11, 2011 1:09 pm 
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Ride: 97 el xr6 sedan

Location: Brisbane
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Hey all.

Just wondering on what kind of compression you guys are getting in each cylinders?

I am getting staggered results.

Before
1 - 175
2 - 175
3 - 175
4 - 175
5 - 155
6 - 150

Found I snapped a piston ring in number 5 an valve seats weren't seating on number 6

After
1 - 180
2 - 170
3 - 190
4 - 190
5 - 185
6 - 180
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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 1:19 pm 
NSW Cruise Moderator
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yep, you got a bunch of numbers there. Same equiptment? same conditions? air temps can affect the comp test. look at the overall resuld, there is a 25spi variance on the first tescond test showed a 20psi variance but on different cylinders. without being silly, are you using the equiptment correctly? I would not think the conditions would be that different that the result would vary so much. are you using a push in or screw in compression tester?

 

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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 1:28 pm 
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Sorry mate, should of stated that the "after" result is now using .20 thou over sized pistons, an a head and block shave.

Screw in compression tester, different tester though on the after test.

I think I may have screwed up the head bolt torque settings.
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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 1:38 pm 
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The second lot of results are ok, they are all within 20% of highest to lowest. I usually run off that as an acceptable variance. Was the valve guides and stem seals replaced when the head was skimmed? If not, that could be an explanation as to why there is only a 5spi difference between before and after. It may be leaking pressure, but I would not think enough to warrant pulling the head. Overall results are pretty good.

 

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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 2:21 pm 
Parts Gopher
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Ride: Ford Falcon EF

Location: Ballina NSW
NSW, Australia

Mine are all 200 psi but number 6 is 0 psi got a valve problem im fixing atm
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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 2:35 pm 
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different equiptment yeilds different results, but providing you use the same tool for the whole job as long as it reads correct, recalibaration can be done later to get the actual result. its the variance you are looking for initially. On this motor the bores have been taken out 20 thou, piston to valve clearance has been reduced, without knowing much more of the picture its hard to say.

Torza80 wrote:
Mine are all 200 psi but number 6 is 0 psi got a valve problem im fixing atm


thats a pretty high comp motor, well 5 of your 6 cylinders are anyway. anywhere from 160 to 180 is common on e series.

 

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 Post subject: Re: Compression readings
Posted: Fri Nov 11, 2011 7:40 pm 
Parts Gopher
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nice they should be all good now head been machined again hopefully there all 200 psi when its back together :D
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 Post subject: Re: Compression readings
Posted: Sat Nov 12, 2011 7:52 pm 
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Torza80 wrote:
nice they should be all good now head been machined again hopefully there all 200 psi when its back together :D



Hey mate,

Curious, what gasket are you running? Headbolts or head studs? what is your specific torque setting that you use?


Cheers for the help.
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 Post subject: Re: Compression readings
Posted: Fri Nov 18, 2011 10:19 pm 
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Wow if a stock ef is 160-180 psi mine is thru the roof. I have a full rebuild high comp pistons and 30thou off the head and au gasket. I get 250 psi per pot last time i checked. Thats why she still pings on Gas :lol: .

 

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