My 73 carbed 1756 cc has started to make a sort of grinding/slapping noise. The noise started this year and has progressively gotten louder. When it started, it only happened at idle. Now, it's louder at idle and even worse as RPMs decrease in neutral. (Acceleration, ironically, seems to be fine.)
I thought it had to be valve clearences out of spec, but I pulled both valve covers off and, at cold, the clearences are all within spec or .0002 lower than spec. I also ran the engine with the exhaust valve cover off, and all lobes seem to be getting plenty of oil. Oil pressure has never been great since I got the car, but I figure that's just because it's old. When cold, the dash pressure gauge MAY get close to halfway on full acceleration, but when warm, at idle, it's down around the 0 reading.
It's easy to pinpoint the #1 exhaust area as the general area that the noise is eminiating from, but not so easy after that. I used the screwdriver/stethescope trick but cannot pinpoint a more specific location.
My question is, should I risk driving to a show on Saturday night 50 miles from home and back again?
Actually my real question is does anyone have any ideas or things to pay attention to when I do get around to pulling the head?
Thanks