External oil pressure gauge - where to plumb and what fittings

[GreigM]

So I've bought a '72 C3 (350) and only managed to do a mile in it and there is no pressure showing on the gauge. It's a mechanical gauge with the thin nylon tube feeding it and would be pretty certain the gauge or tube is where the issue lies, but obviously want to double check the engine is at normal pressure before starting/running it much and having to dismantle the dash. For this reason can anyone advise of an external oil gauge I could buy with the correct fittings to attach to my block somewhere and get a reading?

Also has anyone fitted a supplemental oil pressure switch - I'm reading many issues with these old mechanical gauges and would really like a backup low pressure light - I'm happy with the wiring aspect of this, but is there a place where I can attach a secondary sender for this purpose? And again what is the thread/fitting size - I'm just getting my head around US sizings!

 

[antijam]

The mechanical gauges are prone to seizing up with age. I've just had exactly the same problem - see this thread.
There are lots of oil pressure test kits available on eBay and the like; here's a cheap one for example. It reads to 35 bar and you're unlikely to see more than about 3 bar on your 350 but it should be accurate enough to confirm that you do have or don't have oil pressure. The tapping in the block is 1/8 NPT which is a very common size for this type of connection.
I just replaced my gauge, plastic line and fittings with new items. Works fine now.

 

[GreigM]

The mechanical gauges are prone to seizing up with age. I've just had exactly the same problem - see this thread.
There are lots of oil pressure test kits available on eBay and the like; here's a cheap one for example. It reads to 35 bar and you're unlikely to see more than about 3 bar on your 350 but it should be accurate enough to confirm that you do have or don't have oil pressure. The tapping in the block is 1/8 NPT which is a very common size for this type of connection.
I just replaced my gauge, plastic line and fittings with new items. Works fine now.

Thanks, 1/8NPT is what I'm looking for. I may get a little 1/8NPT t-piece and take a 2nd line there for a pressure switch and put a tiny discrete LED in my eye line somewhere as a double check.

 

[Oneball]

You’ll struggle to get a t piece into the block at the top due to the proximity of the intake, you’ll need to either extend then t or put the switch somewhere else. There’s usual a capped port above the oil filter.