I need to attach a basic universal mechanical oil pressure gauge to a 1973 4.2 engine. The engine is not going in a Jaguar, so original parts are not required.
There is a single pin sender on the lower edge of the block between the oil filter and the distributor. Is this the oil pressure sender? Does anyone know what thread that would be? Is it possible to get an adapter to use NPT fittings?

 

Take the original electrical sender and cut away the top and what's inside until you get to the fitting that goes into the block.
Drill that out to 1/8 pipe thread and from there you can use ferrule fittings with either copper or plastic line.
Remember not to over tighten the nut when using the plastic lines.

A lather is most useful if you have access to one, or a machine shop will charge you a few bucks to drill and tap.

As for the location, others will know, but I need a photo to be sure.

The fitting itself is probably British standard parallel pipe thread or BSPT for short.
There are adapters out there if you look, but I find the other easier.

 

There are two - a switch and a sender. The switch is small and is usually in one of the oil gallery holes along the base of the block. The sender is larger, maybe 2.5" diameter and on the oil filter adapter. The sender has smaller threads, but both are parallel, not tapered threads like NPT is. I believe the threads on the oil gallery bungs are UNC. Not sure about the sender.

 

Not sure this will match your oil pressure line, they do match the Smiths kit and the OEM 120 flex lines.

https://mossmotors.com/jxk-7408-oil-...sing-xk120-140
https://www.sngbarratt.com/English(U...60%20C18641%60
Rgds
David

 

I purchased the 4.2 along with a 3.4. The 4.2 was pulled running from a wrecked 1975 XJ6. The block had 2 small tags on it with "Guarantee void if removed", so it was a rebuilt engine. I fabricated a engine test stand and did a test run today on the 4.2, it failed. It ran good until it warmed up then started running a little ruff. Unfortunately there was water in the oil after the test run. From what I've learned, it's a head gasket, cracks in the cylinder walls or both.
It's probably not worth fixing. I will most likely just part it out.

 

Read from post 25 here.

https://www.jaguarforums.com/forum/m...-244091/page2/

https://www.jagtas.org.au/torque/tec...-engine-block/

 

The 4.2 I have is a 7L**** block. The chart shows the 7L to be 1968-1973. Does this version of the block have liners? Do all versions of the 4.2 suffer from cracked blocks?

 

I have a 1976 XJ6 with a 4.2 engine and cracks between the bores! It does have bore liners and there is a repair system available that involves replacing the liner with a special "top hat" liner. It is a long expensive process if you can find someone prepared to do it! I replaced my engine with a later fuel injected engine, and concerted it back to carbs! AlesG.