A spun main or conrod bearing will not affect compression. Use a long screwdriver like a stethoscope: With the engine running, place it at various points on the block (i.e. camshaft housing, front of block near crank pulley, rear of block near where the crank bolts to the flywheel, etc.) and place your ear on the handle. Noise travels up the shaft of the screwdriver, enabling you to pinpoint whereabouts in the engine the noise is coming from.

Oh, and for the love of God, please don't put your face into the fan and if you have long hair, tie it back!! :-O

Ah! You're referring to the sensor that tells the ECU when the engine is warm, thus leaning off the air/fuel ratio, or ceasing the cold start (aka "auto choke") mode.
If the sensor has 2 terminals like a non-EFI sender unit, the plug would still be the easiest to change to suit a sensor that fits the manifold, as it doesn't matter which way the wires go. Try taking the sensor unit to your local Auto One or equivalent parts store (not Super[market]cheap as they generally don't know #OOPS# from clay) and tell them what you want. If my local is anything to go by, they'll pull the Trident catologue and try to find you one that is the same length to suit your manifold thread diameter & pitch. There might even be one with the plug you need too.
If you do find one, buy 2. If you plug the spare into the harness but leave it hanging free, it will read the ambient engine bay temp. This will make the ECU think that the engine is still cold and may show up as a fault, but it will make your engine run fatter!

Come to think of it, isn't the L's temp sender unit located in the head, like the A's? I'm more A series than L, so forgive me if I'm wrong on that...

What motor you running? A Series & L Series share the same sender unit if that's any help. Also, the easiest thing to replace would be the plug itself.

First time viewing for me too. I was thinking of getting a VG30E to replace my D21's tired old Z24, but you've got me pondering now D!
Then again, reality and stuff considered, maybe I should say delusions of grandeur...
On another note D, not sure if you're still thinking of selling your VeeBee, but have you seen the latest posting on 1000.com?

Yep, just a form of series resistor is all they are. What engine is the sender unit and harness from?

I beg to differ. If anyone has built a B10 well, it's Chris. Plus B10's are starting to appreciate cos after all, it's what the cool kids ride!

Why change a metric thread to imperial? Wouldn't it be better in the long run to get the correct sender unit or retaining collar to suit the manifold?

Sounds good mate, over a beer even! I was chatting with Neil last night too, methinks a Perth 'Thou ketchup might be on the cards champ, what do you reckon?

G'day Mike, how've you been champ? Hey I don't suppose you have an oval port manifold to suit laying around, doing nothing but providing a warm home to spiders, that you might part with?