Brian - you're right - I've been a bit vague on the noise - mainly because it's difficult to describe. Need you and Oscar to work out how to add a soundtrack to this board!!
OK - let's do the oil pressure thing first, which I've covered on this board before, but never really bottomed out. I just use Katy now for about half a dozen or so rallies a year with a bit of fun stuff in between and always drive to and from - maybe up to 2 hours each way at pretty much full speed. I change the oil and filter every year and for the last couple of changes have used the Halfords multigrade vintage oil that I think you said you use in Henrietta. Before that I used good quality oil - usually Castrol SAE40. Ever since I've had her (over 10 years now), I get about 40 psi on cold startup, but after 10/15 minutes running, the guage drops back to zero, with no noticeable change in engine noise. I'm no skilled mechanic (as you'll have gathered), but I've been told this probably means the engine is well worn but the pump is giving out lots of flow and that is protecting the bearings. So to answer your question, I've NEVER had oil pressure!
So I'm hurtling along a back road - been running for probably 10/15 minutes, everything nice and warm, when there's a 'ping'. The best way I can describe it is, it was like a heavy washer hitting the inside of the rocker cover at speed. It was not like a stone hitting a fan blade - not like a noise made by something in free air (heavens this is hard!!).
The engine continued to run and there was no misfiring or smoke from the exhaust, but it started to labour a little and .... sorry .... just got noisier in a way that someone who has listened to it for many happy hours would know it was noisier. Definitely not a heavy knock or even a light one - more a rattle, but not of something light and loose, something with a bit of weight in it being shaken about. I did a smart about turn and drove gently home at half throttle and the noise seemed louder towards the end, but that could have been my imagination. It wasn't so bad that I thought I should stop before a conrod joined me in the driving seat.
I've had the rocker cover off and there's no sign of anything adrift. I have not taken the plugs out and wound the engine over by hand yet to see what's happening with the valves etc, but maybe this weekend, if I can make the time. I also want to drop the plate off the sump and check for debris - anything to give me a clue as to what went 'ping'!
If I can't find anything obvious, I'll need to dig deeper to find the cause and that's when I'll need to weigh up whether I want to go down that road or not. As I said in an earlier post, I can't see me taking the guts of the engine out without, at the same time, separating the distributor from the oil pump drive (it's jammed in and the distributor needs an overhaul) and fixing the gearbox to back axle seals, and reconditioning the steeringbox. Oh and while she's off the road, I'll probably think about sorting the brakes and cables - so the list goes on and on.
I love the old girl, but having already spent a bomb on getting it back together from a heap of bits 10 years ago, I'm not sure I'm able to do the same again. I'm going to see if I can overcome the Photobucket thing and get a 'before' photo on here, so you'll see what I mean.
There you go - bet you're sorry you asked!!
On our way to a local meet when there was a 'ping' from somewhere inside and soon afterwards she began to make the kind of noises that tell you all is not well. No sign of trouble inside the rocker cover, so the next task will be to drain the sump through a sieve, then have a look/feel around inside, just in case there's a lump of something obvious to point towards what is wrong.
If I find anything spectacular, I'll try to upload some pics.
