Oil pressure dropped

[Fetta GTV]

 I was doing the timing on the sprint tonight, car was running well. set timing fan came on while doing this, all good.
then the engine started to sound wrong. still idling OK.
went and looked at the oil gauge and the pressure was down near 0 not on 0 bit close, goes up when I rev.
Pressure was always at over 40 when idling.
When starting the red oil light goes off after about 1-2 seconds.
It could be the gauge I guess its just that the engine sounds wrong.
Can I just hook up a mechanical gauge to the fitting above the oil filter to check pressure.

Also noticed that the engine runs better with the oil cap off, I think I may have a blockage in the pipes that go to the top of the carbies

Any advice greatly appreciated

[Mick A]

Please give more detail on how the engine sounded "wrong" to help answer your question.

[Fetta GTV]

hard to describe, it sounded dry if that makes any sense at all. like a rubbing noise. sorry I know not very descriptive.
I started it up after it cooled down and pressure was good and engine sounded fine.
When it gets hot enough that the fan turns on and off it makes the rubbing, dry sound and is not as willing to rev.
Almost like when it is hot something is expanding and rubbing.
took the fan belt off to see if it was the waterpump or alternator making the noise but it still did it.
Sorry again for being vague

[Mick A]

Obviously without seeing this it is very hard to diagnose. Posting a video could be a good option.

What you describe sounds like a vacuum leak, at least the rough idling symptom anyway.

See if it's firing on all four cylinders. Lift one plug lead at a time to check and observe.

Sometimes rear main seals make a bit of noise, but only usually on freshly installed ones.

Low oil pressure reading is most likely just the gauge. If you had no oil pressure, you'd know about it!

Once again, this is all speculation and guesses! But hopefully it can point you toward the right direction.

Cheers. -Mick

[Fetta GTV]

Appreciate you taking the time Mick

Oil pressure is OK, it was the gauge, bad connection. So that is a relief. As you say I would know if it had no pressure.
I am going to give the breather pipes a good clean, it seems odd that it runs better with the oil cap off.
I an still getting the dry rubbing sound when the engine warms up. I will try to get a video and upload.
It does seem that something is getting tight when the engine gets to full temp.
It idles and run perfectly while it is heating up. It even idles OK when hot just got the noise and it is a bit hesitant to rev from idle.

Thanks again
David