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NoBozo · 03-07-2012, 01:05 PM

Here's a quote from my 1963 Jaguar XKE Factory Service Manual:

"Compression pressures must be taken with all the spark plugs removed, carburetter throttles wide open, and the engine at it's normal operating temperature."

As stated in a post above, the engine is turned over continuously (coil wire disconnected) until the pressure stops climbing on the guage. Write the pressure down for that cylinder, and move on to the next cylinder.

NB

EDIT: Just as an example, the 3.8L Jaguar engine with an 8:1 compression ratio should produce 155 PSI. With a 9:1 compression ratio the pressure should be 180 PSI. What's more important is that all the cylinders show similar pressures.

03-07-2012, 01:05 PM	#12
NoBozo Senior Member Join Date: Jun 2008 Location: Portsmouth. RI Posts: 2,231 Thanks: 400 Thanked 460 Times in 308 Posts	Here's a quote from my 1963 Jaguar XKE Factory Service Manual: "Compression pressures must be taken with all the spark plugs removed, carburetter throttles wide open, and the engine at it's normal operating temperature." As stated in a post above, the engine is turned over continuously (coil wire disconnected) until the pressure stops climbing on the guage. Write the pressure down for that cylinder, and move on to the next cylinder. NB EDIT: Just as an example, the 3.8L Jaguar engine with an 8:1 compression ratio should produce 155 PSI. With a 9:1 compression ratio the pressure should be 180 PSI. What's more important is that all the cylinders show similar pressures.