<VV> 140 noise getting louder

[Rod Murray]

Aapparenty a funny thing happens when your sunday toy becomes a daily driver...little issues become potential problems... here's the deal...

I hv a 3-year old 140 (currently 2 carbs) w headers in my 66 convt (yes the same convt w the sticky power top gears reported earlier this week - will report back as soon as that's fixed).  Seems to be running fine overall based on all guages and idiot lites normal and maintaining good mpg (even better following fresh plugs). Oil level is fine. However, I hv a "vibrating", almost metallic/tin type noise coming from the engine area (do a spanish "RRRRR" sound w your tongue to get the idea) - increases w rpms and seems like left ear hears it most from drivers seat but hard to tell. Most noticeable during acceleration above 2k rpm. Don't hear it at startup, normal idle, revving in the driveway, coasting in neutral, or when I take my foot off the pedal for stopping. So apparently only during load. 

Our club mtg is tonite so I'll have a few more experienced ears available to drive around the block for a listen. But in the meantime, just wondering if anyone on VV recognizes what I'm trying to describe. I've never run the car hard, but since I equate noise w damage, my greatest concern is wasting a motor that up to now has been performing well. And since its become the DD, its gotta be reliable. 

All thoughts appreciated. 

Thx, rod
Vintage corsa
Starting to spend more time underneath than behind the wheel
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Thx, Rod 
(All thumbs - pls excuse typos)