Sorry , I seem to be asking a lot of questions lately .
I have fitted new filter and new oil . I removed the plugs and spun it over on the starter . No pressure at the gauge . I have removed the supply pipe at the filter housing and zero oil from that when spun over , Any ideas what to do next ?
Thanks Jim
With the plugs out and the oil canister pre-filled with oil, my experience is that it will take a good 20 seconds of continuous cranking to register oil pressure at the instrument panel.
With the plugs in and starting the engine, oil pressure registers almost instantaneously.
Jim,
And if you didn’t fill the canister with oil before installation it will even take longer… (Guess how I know!).
Bob K.
Canister was filed , I just tried a 30 second crank and still nothing .
Being somewhat? anal about first start I always pump a quart or so of oil through the main oil way down the side of the block and have an oil filter canister with a pipe coupling welded on it used just for 1st starts ups.
Have you removed the distributor cap while cranking to see if the rotor is turning? The distributor and the oil pump are driven from the same gear at the nose of the crankshaft. If the rotor in the distributor is not turning then the issue could be with the brass gear that drives them. (The photo is not of an XK120, but similar)
Hi Mike
I have have spark at the plugs , so the rotor must be turning. I thought it may be the gauge, but with no oil from the gauge feed pipe that rules that out. Could it be sticky relief valve ? I guess this engine has not run for more than 10 years
My initial thought was crud buildup inside the filter head, preventing the internal bypass valve from opening, or holding the external relief valve open.
Here is how it all works.
I have removed the filter head and it was quite clean .
I cranked the engine with it removed and I was expecting oil from the block , but absolutely nothing. Does that point to the pump ? The sump doesn’t looked bashed in.
When I tried to get oil pressure by spinning, I couldn’t get pressure either. I had cranked so much, I was worried about damage. Folks here just said “start it up”. I did, and pressure came up right away.
This was on an engine that had been out of the car for a long period. I wouldn’t expect the same occurance on a regular oil change. You didn’t mention how long it has been since yours ran.
Good luck,
Rob
My guess 10 years plus since it last ran . It crossed my mind to just start it ???
Now that you have the filter head off, note that port in the engine block I labeled “From Oil Pump” in my first picture above. Try filling that up with oil with a hose and funnel, then try cranking and see if oil pumps out of there. It will make a mess on your garage floor of course, but it would be a happy mess. 
Thanks Rob
tried your trick. Some oil came back out , but only what I put in then the flow stopped . What do you deduce from that ?
If oil came back out, but only the amount you put in with funnel, that at least suggests there is an oil pump in the engine and that it can pump oil (and maybe some air to push the oil). If there is sufficient oil in the sump to reach the pump correctly, then clogs are suggested in screens or lines. If you are continuing to turn over the engine with it “dry” on oil, maybe you would benefit from a pressurized oil tank giving initial lubrication to important bearing areas and also some oil on the piston rings with the plugs out.
"pressurized oil tank "
How do I do that ?
I deduce that the pump is turning, but not picking up.
Here is what you have in there (pump and basket shown upside down).
The screen basket fits in that big hole, and the pickup tube fits in the middle of the screen through that hole in the small cup, and picks up whatever oil is between that small cup and the bottom of the sump.
Is your sump dented upwards there?
That is what I thought , but to not pump anything is wired . Could there be some sort of air lock that slow cranking will not shift ?
The sump looks in perfect shape .
IT LIVES…
I fitted my overhauled carbs and hot wired it and to my amazement it fired and ran immediately… The oil pressure came up in a couple of seconds and it sounded pretty good , despite only having the down pipes of the rotten exhaust still hanging on . I was so busy congratulating myself that I didn’t notice the large pool of oil on the floor . It is coming from the oil filter , so I probably have the seal in wrong . But still very pleased .
Well, that’s something to cheer you up after all the metal bashing!
Eric
I predict your FHC will be the star of XK80!