Compression test

[metallicareload99]

Dumb question, but by removing the carb/throttle body for compression testing am I "invalidating" the results?  I know you are supposed to hold the throttle open, but it's convenient to remove it completely before say pulling the whole engine.  Thanks for any advice

[XH29N0G]

I think that would do the same thing to manifold pressure as wiring the carb open.  There is also an issue with cranking speed and engine temperature.  I know cranking speed and carb being wired open make a big difference.  I do not know about engine temperature.

[BSB67]

I'm always amazed how little the open carb verses closed carb changes the readings.  Same with temperature.

[metallicareload99]

This has been how I was doing it the last couple of times, but I never thought it would be an issue until the last time. I got a couple of cylinders that were 170+ psi which seemed extraordinarily high for a 9:1 motor.

As far as temperature, I don't recall ever being able to test my engines hot. Matter of circumstance that the car is in storage and cant be brought up to operating temperature. Good points about battery and starter condition, as I'd think those would have a large impact