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Engine rebuild - compression test ?

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Old Mar 17, 2013 | 07:36 PM
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seasicksteve's Avatar
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From: Norfolk, England
Engine rebuild - compression test ?

Has anyone had a compression test done just after having their engine rebuilt ? Or been given test data on collection of their rebuilt engine ?

I've had my engine compression tested 1200 miles after a rebuild due to poor starting and it failed to get within usual parameters. I've been told by the rebuilder that the compression gets better and better after the rebuild as the seals bed in. This seems strange to me as I would have thought the compression is best from day 1 and would get worse not better ?
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Old Mar 18, 2013 | 02:28 PM
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Carbon Fibr's Avatar
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From: Alliston Ontario
seems like you got unlucky and got the lemon of the bunch.

compression should be good right off the hop
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Old Mar 18, 2013 | 04:42 PM
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Thanks for your confirmation.
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Old Mar 18, 2013 | 05:12 PM
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I recently rebuilt my engine, I reused my housings, rotors, eccentric shaft and irons. I have all brand new seals, jackets, etc... I did a compression test before i even put the engine in and I got 120 +/- psi on all faces. Then again my housings were in very good condition. I have heard that if your housings are not flat, then you have to break in your seals....never experienced it. Some people even have trouble starting them from a fresh build, they have to pull start their cars. They claim to drive around for a few hundred miles and it idles like a champ... i believe that their is a thread here that you can read up on.
https://www.rx8club.com/tech-garage-...ebuild-195276/

I also had a very low compression engine on a build i did......it happened to be i installed solid corner seals (not recommended). I couldnt start this one at all, it had 60psi. It is very important to measure all your clearances.

Good Luck.
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Old Mar 19, 2013 | 07:41 AM
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seasicksteve's Avatar
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Originally Posted by chepetech

I also had a very low compression engine on a build i did......it happened to be i installed solid corner seals (not recommended). I couldnt start this one at all, it had 60psi. It is very important to measure all your clearances.
I don't think this was part of the rebuild kit but would be replaced if originals were worn. Think I'll check that with the garage.

Thanks for the link too.
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