I have been searching for the firing sequence, compression ratio & OEM cylinder operatng pressure for this engine for the last hour, but have turned up empty handed.

I am working on a 1985 XJ6, with the 4.2L engine.

Any help would be greatly appreciated.

Thank you!

 

1 5 3 6 2 4

#1 at rear of engine

USA spec compression ratio 8.0 to 1 (or 7.8 to 1 on some spec sheets)

You'll want to see about 140 psi on a compression test

Cheers
DD

 

Doug, you are the man!

I currently have

Cylinder 1: 131 psi

Cylinder 2: 135 psi

Cylinder 3: 135 psi

Cylinder 4: 136 psi

Cylinder 5: 135 psi

Cylinder 6: 122 psi

not bad for a 1985 car at all!

 

Yeah, you're in pretty good shape...only one low and it's within the 10% range

Cheers
DD

 

wondering if anybody has links to a thread where someone has torn down one of these engines.

I just want to see what I'm getting into,without having to tear into a perfectly running engine (disabling the project vehicle)