Hi Folks,
67 2+2 4.2 engine. To conduct a compression test, I have, in the past, disabled the fuel pump and pulled the cable from the coil. Would there be any problem with simply not turning on the ignition key and using the button, only, to turn the engine and check the compression?
Gary
That would work.
Engine is supposed warm, throttles open too.
and all plugs out…
… Battery charger connected…
Pump oiler handy for checking the rings
The engine would not start with the plugs out.
Walter
Thank you for all replies!! Much appreciated!!
Still better to disconnect the pump the coil so there’s no spark looking for a way to ground; fuel won’t be sucked in without compression, for me it would add a little safety to run it dry.
And the battery should be in good nick so it doesn’t crank much slower towards the end! Or charger. But not really required.
Why…does the Jaguar Factory Service Manual, page B63 state for compression that the 8-1 spec is 120 psi…when everyone seems to look for much more…around 150 psi?
The manual calls for 70C, all plugs out, ignition off -use the solenoid button. Not stated but all say, throttles open…
why 120 psi as spec?
somewhere i think is a spec for 150psi , still for the 8-1. ? I can’t find it…but what would have changed to increase the psi?
Nick
I think that 120 figure is a goof…more like the calculated PSI, rather than the cranking pressure, even though the Manual does refer to the cranking pressure. There is another anomaly in the Manual about this: it states an even lower value in one section for the Mark VII, IIRC.