My 94 XJ12 6.0 V12 has been sitting for 2 years and I just did a compression check on it. The Jag manual states it should be 200-240psi. However I have always been told you want all the numbers to be very close. So question is what do you think of my results? I have a 40psi range...250 to 210

1B 250psi 1A 245psi
2B 240psi 2A 225psi
3B 230psi 3A 235psi
4B 240psi 4A 230psi
5B 210psi 5A 220psi
6B 220psi 6A 240psi

 

The usual recommendation is 10% max variance. You're beyond that. The question is, what are you willing to do about it ? If the answer is 'nothing' then there isn't much left to discuss!


How does she run?

Cheers
DD

 

if it's been sitting for 2 years I would not be too concerned yet. Run it and use it then check it again later on. I think you will find it will probably come good.

 

For a motor that sat for 2 years, I think its pretty good, rings become sticky and cylinders dry right out giving false readings. As Baxtor said, Drive It for a bit, and test again.
I don't have exact figures in my library's but anything over 200 is good.