Engine Noise
 

Very recently a noise has caused me some concern and I am interested to know if anyone can point me in the right direction before the situation becomes 'expensive'.
The engine is a 74 2.7l in a 72 Targa.
The noise was first heard clearly from inside the cabin (No engine sound deadening pad) at start up with the engine cold. If started at low revs, all ok but as soon as revs pick up the noise kicks in. I first thought it was very much like air being forced through the oil tank, a serious 'bubbling' sound.
Oil pressure is fine and oil level where it should be at a warm idle. Lifting the engine cover it is very difficult to pinpoint where it is coming from except the sound takes on a new tone, perhaps more metallic. I don't think the tensioners are upgraded.
The sound disappears once the engine is warmed up at which time the engine sounds great .
Any ideas are welcome.
Cheers
Chris

I have a 75 with a 2.7. I had a similar situation and couldn't figure out where bubbling sound would come from on an air cooled motor. The key for me was to hear it after I shut off the motor one time. Turned out the muffler was full of water/oil/fuel from plenty of short runs prior to my owning it.

I took it on an extended freeway run to boil it out. BTW, it smoked like crazy on the way out. No problems now.