Compression on 5.7 EFI
 

What should the cylinder compression be on a 5.7L 350 EFI motor (1999)

dumb question, but I've only done compression checks on 2 stroke motors with kill swtiches, but what is the best way to disconnect the coil to avoid sparking/coil burn out when doing this test?
Please be specific, I'm in learn mode here!

As long as your kill switch is in the off position, you should be fine. I just ran a compression check a couple of weeks ago with no problem.

I don't have a kill switch.
Anyone on the proper compression numbers on this motor?

Just take the coil wire off. The PSI should be around 140-150.
As rule of thumb all cylinders should be with 10% of each other.
You don't want to see 150 in one and 90 in another:eek:

By coil wire, I want to clarify. Is this the wire that goes from the coil to the distributer?

On an engine equipped with the Delco EST distributor I usually remove the two harness connectors at the distributor, for T-bolt systems, I just take the wires (purple) wires off the positive side of the coil. Just removing the coil wire is not a good idea.

For a good compression test you should have a fully charged battery and the throttle plate wide open. It's ok to do it on a cold engine. You probably should see about 170-180PSI on an EFI small block. Big block would be more in the 145-165PSI range.

Dave