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compression test and injector question


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Currently I'm thinking about ordering a set of TEA 317's for my mostly stock lq9. My truck currently has 148k miles on it. Now for the question. I would love to put these heads on my motor but I'm concerned about general wear and tear. What would you guys consider a safe compression test readings before needing a full rebuild? Now for the injector question. I know there is a such thing as over carbing a engine but does efi follow the same rules?

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  • 4 months later...

Do a leak down test, not a compression. If you are with in 10-15% leak down, mod away, as for injectors, as long as you are porperly tuned for them, the PCM will not over fuel the engine. It will just use less injector duty cycle. IF you do larger injectors with no tune, then yes, the engine will flood with fuel.

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Do a leak down test, not a compression. If you are with in 10-15% leak down, mod away, as for injectors, as long as you are porperly tuned for them, the PCM will not over fuel the engine. It will just use less injector duty cycle. IF you do larger injectors with no tune, then yes, the engine will flood with fuel.

how would one do a leak down test?

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I too would like to know this since my 03 ss has 139k on it and i am considering doing either 408 kit or blower but am worried about the motor.

If you do a 408 build the bottom end of your motor would be new... i think i would bo that before i would even consider putting a blower on it.. just my humble opinion

Edited by SS Muscle Truck (see edit history)
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[quote name='battousai'

how would one do a leak down test?

 

You will need a special tool with two gauges. You feed in compressed air into each cylinder while the piston is at TDC. The first gauge will read the psi in the system, the second will give you the % leak down. If you have a problem area, you will hear where you are leaking compression. I.e. intake/exhaust valves, head gasket, piston rings...

Sent from my ADR6400L using Tapatalk 2

 

 

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